Callan's Commodore ventures :)

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You'll get this blurb again, but you'll then be able to read the rest of my trials and tribulations!!

 

 

Back in the Early/Mid 80's, I was an Australian Commodore 64 hacker. Probably not  a very good one - but I didn't kill any gear, and actually repaired a fair bit of friends' equipment (the 1541, in particular was not the most reliable piece of kit in the Commdore Lineup!!).
**bless me padre for I have sinned ** - I was also a cracker, and had quite a good gig with friends in computer shops sending me programs to crack - which I would later circulate. It's a wonderful (if dodgy) way to learn your way around the 6502, and Commodore hardware. In due course, protection schemes moved into the disk drive, and of course I had to follow. With the help of a fantastic book "Inside Commodore DOS", another more in-depth, but sparsely documented ROM disassembly, and Drive/64MON (by Mike Henry of Starpoint software - a totally awesome virtualising machine code monitor, that could operate virtually inside the drive) - I was soon cracking (and writing!) code for the 1541 Drive. It was about this time that the love of my live, my (now) wife presented me with the most romantic gift a woman could give a budding geek - a dolphinDOS kit for a Commdore 1541... Much wow and enjoyment was had from such a brilliant piece of kit.
Effectively it's an 8K RAM expansion ($8000-$9FFF), 24K ROM ($A000-$FFFF), adds parallel port data transfer, and 40 track operation. The 8K RAM expansion allows entire tracks to be cached in the one revolution, and the extra ROM allowed for the extra routines, and a less memory efficient (but faster) GCR<>BINARY conversion. ON the PC side, a basic ML monitor, DOS wedge, enhanced screen editor, unnew, and other goodies were avaliable. As I said - a brilliant piece of kit.
Come 1992, and time constraints, growing family commitments, and a blossoming (computer) engineering career, and  my poor Commodore gear was stored - but not forgotten.
~~~ Wavy lines of the passage of time ~~~
It's now 2010, I've been retired for a few years (retired at 41) to spend more time with my (now) wife. Just over a year ago, my C64 was out of storage, and, with a new PSU, working just like a bought one :). A new-ish keyboard was procured (the old one was literally worn out), and everything was setup. I've also recently procured a complete C128D setup (including monitor), and spare 128 for (as last resort) donor spares. I have my eye on expanding the collection, too. I still have some PET B & D series gear, a D9090 HDD, 4040 and 8250 in storage. I'm currently starting to get my head around the C128 - it's a VERY different beastie. Whereas the C64 felt very "bare metal" - the C128D feels a bit less of a hacker machine. Part of that, I'm sure is due to the necessarily increased complexity, and partly due to my lack of familiarity. Crikey, the 8563 VDC, with it's ported video - is a weird and clumsy thing to drive... 
But back to the DolphinDOS... 
The first thing I noticed was that the Parallel speedup was sending data with stuck bits. No problem - the 6522 in the drive had a blown bit or two -  I pulled one out from a donor drive, and all appeared fine. 
It soon became apparent that when the drive warmed up, weird stuff was happening. data coming off the drive was being silently corrupted - and worse, the drive was FALSELY reporting error 23 errors (checksum in data block). These problems vanished when the DolphinDOS was disabled.
Suspecting RAM, I swapped out the 2K RAM in the drive controller - but the problem remained :( 
I'm currently exploring a couple of theories in parallel: (http://www.lemon64.com/forum/viewtopic.php?t=41396 has more detail of my travail)
1: DolphinDOS RAM is faulty - fails when warm. I've ordered what I believe to be the correct part (a 6264 replacement - AMIC - A623308A-70SF), and I'm awaiting it's arrival. I'm a bit concerned - it's quite a bit faster than the encumbent chip (70ns Vs 100ns) - but since there's now whacky timing stuff going on, as is the case with the C64/128) I'm not that concerned.
2: Although the soldering on the daughterboard looks of high standard, I'm very suspect of the 6502 CPU piggyback socket. it's a closed, single-wipe design that I've had a lot of problems with in the past. It's possible that a temperature-related fault may be causing the symptoms.
3: The enable-disable system is really dodgy - Basically A15 from the CPU is bypassed and either shunted off to the board (giving it all address space from $8000> ) - or wired back to the controller board. Problem is, this switch is connected to a return length of 37cm of  suspect, IDC wire (crimp wiring) - with pretty average soldering on the switch. Whilst I believe you can take some liberties with the 6502 buss, I think that may be taking just a bit too much of a liberty with the lady. Although the propagation delay of that would only be about 1ns, electrically it could shake things up a bit (as it's not carrying a state, but an actual signal)- so I'll be experimenting along that line of enquiry. 
The real kicker - The makers of the device (Micro-accessories SA - in my hometown of Adelaide, Australia, no-less) - sold it through Ingram Micros, I believe - ground off all the chip markings of the discreet logic chips..
Ah - the joys of playing with 27 year-old gear...
 
Callan
 

AHA! - detective work yields some results!

Ploughing through various dark corners of the internet, brought me to THIS SITE.
Flipping idly through the pikkies, first I spotted a blurry picture of a DolphinDOS board - very similar to mine - and underneath it, a device called a RAMBOard. 
The RAMBOard device (there are various versions) - is a device that adds 8K RAM at $8000, and a custom replacement DOS ROM - and it looks like a dead ringer for the DolphinDOS board.. 
Some googling later, and I end up at THIS SITE - Which has some schematics and theory of operation  WOOT.
The schematics arent' a perfect match, but they now give me a starting point - WOOT!!!
More homework over the next few days...
 
Callan
 

Back to Video issues

THere has been an interesting thread on at lemon64, in relation to Svideo output quality - more in line with my original approach (IE bypassing the planar board, and generating Svideo on a clean circuit) - and some good success has been had. The thread is  HERE .
(Unfortunate name for a forum - First time I saw it, I thought "lemon party" (NO DO NOT GOOGLE it - what would be seen cannot be unseen). It's apparently the name of the guy who runs it.. )
It appears that part of the video out signal (even for the composite/Svideo) is processed within the RF modulator - and this method bypasses all of this - with signals taken directly from the VICII chip itself. As I mentioned, much more in line of my original approach. Interestingly, most of what is thought of as clock-noise appears to have disappeared - if his screenshots are to be believed!
The circuit looks simple enough (a couple of transistors, a stack of resistors and a diode or two) - and, most excitingly (for me) - can be directly translated to the C128.
Looks like a trip to the electronics parts shop is in my near future. Got a lot on this week, though - body corporate matters, and starting renovations on a new property - and my bloody bronchitis is STILL giving me larrry-do... 
 
Callan
 

Yes the signal is mixed in

Yes the signal is mixed in the modulator and it is a bit of a strange creature, it is peaked and tweaked for the VICII and the 1702.
The specs for the modulator was taken care of with the vendor Mistumi by our Tokyo office. Unfortunately they often tracked behind the issues by about 6 months so I have observed them making a problem worse after the silicon was changed to fix it.  They also would take it upon themselves under direction at some level to fix things, which was good, but we had to learn to talk to each other more.
By the time of the C128 we were in each other's offices so much that we fixed things more real time.  Noise has to be fixed at the source typically, not patched over with a bit of resonance in the circuit path.
Bil

Developments with drive issues.

Well, Got my 6264 Sram chip in the mail yesterday (actually got several - if you're paying for postage, and the chips are $10 bucks each, might as well get several - it's not as though they go off in the 'fridge).. 
I measured out Vcc & Vss against the spec sheet, to make sure  I wasn't at least going to blow it up when I replaced the unmarked chip, and then whacked it in.
The GOOD news is that the drive fired up, the RAM was detected by DolphinDOS, and it did the business speeding up load/saves +1 for my amateur reverse-engineering skills :D) . The BAD news is that the problem still persists../cry. 
With the RAM enabled, after about 10 minutes running a test program, the drive bombs out with errors (23/25) The test program just does internal copies of a 250 block file I created. (c0:file2=file1 / s0:sourcefile / c0:file2=file1 ) - in a suitable basic program. Disable the RAM in DolphinDOS (@XR-) - and it runs fine.
Next job is to replace the suspect sockets, check the board for fractures, sweat all the joints, and tidy off the enable/disable switch and cable. Bah! - and my eyesight isn't quite what it used to be.. Getting old... 
Thanks for the background, Bil - it makes a few things gel.
Haven't had a chance to get the bits for the external video mix circuit alluded to in the earlier post - Building work on the new property (well more UN-building work atm :) ) started today, and the body corporate business for the block of apartments we live in soaked up the rest (got the much embiggined) budget through the AGM, which was a relief .
 
I think at least part of the problem is   subjective, too - we're all used to supercrisp digital 1920x1280 screens, and interfacing 30-odd year old kit to modern display equipment is always going to be a bit hit and miss. There are some who just don't understand the inherent limitations and artefacts inherent in phase-encoded colourburst synchronised colour signals, and the inevitable weirdness that occurs when an interlaced signal is displayed on a frame-grabbing display (like LCD's) - so to some extent, many seem to have unrealistic expectations as to the output.
Still, sapping out the signals clean from the chip, processing it EXTERNALLY, and squirting it out a dedicated port has gotta be a bettter way to go - and it is, as I earlier waxed - directly applicable to the C128. 
Oh, and my bronchitus is finally clearing - yay.
Callan
 

Fun day going retro

I discovered a Vic20 in my garage today - 15 odd years ago a friend of mine gave it to me, as he wasn't using it - and it's remained there ever since.
It was more than a little dusty for it's time in solitude, but, after a bit of cleaning, looks in mint condition. 
Pikkies?? - have a gander at MY FLICKR set 

The RF modulator seems dead (couldn't find a signal on the TV) - but I knocked up a composite / line-audio cable, and it came straight up!. 
It's an early model (9VAC input, latest chip date first week 1982), and the old pet-style keyboard. (it looks rather quaint). 
It hasn't survived completely unscathed.. There is a small amount of corrosion on the user port, the cartridge port is a little fussy, and some of the internal conductive-rubber contacts inside the keyboard are a bit erratic) - but nothing that can't be easily attended to. 
The Datasette needs a full overhaul, and new drive belts (old ones are badly stretched - hardly surprising) - so I'll measure those and get them ordered (plenty of places sell them)
The VIc20 was the first Commodore machine I ever used. I didn't own one at the time, but my cousin had one - and we had a heap of fun with it, both with him, and with my totally wonderful uncle - Uncle David - may he rest in peace.  I have fantastic memories of that time.
 
I'm personally stunned at the condition of it - and it's a fantastic addition to my collection.. 
Now, I ALSO know that theres a PET2001 (non-chicklet keyboard), a couple of Bseries PETs, and some dual drives (including an 8250) in the garage, too (better protected, too) - but I think my wife would throw me out on the streets if I brought them to the apartment......... 
Over the next week or so, I'll have some fun!
 
Ooroo
Callan
 

The Mail arrived today.

My Jiffy DOS's arrived today from Retro Innovations - a webfront run by Jim Brain. Jim flogs a useful range of modern gear, mostly designed to interface Commodore kit to modern equipment - EG: His totally excellent Zoomfloppy device -which is a USB<> Commodore IEC interface - perfect for managing disk images and files to and from a PC.
My main 1541 now has Jiffy DOS installed, so my (ailing) DolphinDOS daughterboard has been pulled, and is now awaiting a full teardown, reverse engineer, and repair. I intend to strip it back to the bare board, document the circuit, and then see if anyone can work out the undocumented chips (shouldn't be too hard - I've 1/2 worked it out already - still, doing so will allow others to perhaps make them. I'll check for cracks in the tracks, and then fit new sockets, and replacement logic chips. **HOPEFULLY** THAT will finally nail it's reliability issues. 
Unfortunately, the JiffyDOS for my C128D is flakey - when using the 128 firmware ROM (in C128 mode), it keeps spontaneously dropping via BRK into the monitor - so it's feeding corrupt data to the processor, methinks - Another one is on it's way (for an unrelated project), so I'll wait until it arrives, and try that one, before going further. I'll let Jim know, tho, and work out what the best course of action is - I'm in no hurry - frankly Burst mode is good enough. Man the 128D is a sod to tear down, though. 
Fixed the VIC20 keyboard on Sunday - it's a really early one - looks like a modified PET keyboard, and has the round rubber contact pad (instead of the "bridge" one that came later.  I'm quite tickled with it, and although it's likely to soon go back into (somewhat BETTER) storage, it's awesome to finally have on.
Got the bits for the replacement video circuit on the weekend, too :) - in my infinite spare time, I'll start working on that.
Fun Fun Fun.
ooroo
Callan
 

Just a quickie

Well, I stripped the DolphinDOS daughterboard tonight - unsoldered all the sockets. I'm actually surprised it too such a short time - I haven't done much soldering in many years - surprised at how quickly I got back in the groove. I realised that the replacement sockets I bought were 16 pin - I need 14 pin - so it's off to my local electronics supplier tomorrow, to get some.  I also will take some hi-res images of the PCB, sans sockets, so that others more knowledgable than I can help me work out what the glue chips are. (the markings have been ground off). 
I've gone over the board, and identified (and resolved) several possible partial shorts (there is no solder mask on the board), and a cracked trace. The trace wouldn't have caused any internal data corruption - but might cause flakiness on data transferred, as it's en-route from the 6522 VIA I/O port, and the parallel port connector.

I found a fascinating site on PAL/NTSC standards, and how they work. It also covers such things as the impact of chroma signal bleeding into  luminance in Svideo,  the reasons behind dot-crawl and checkerboarding, and other issues such as red tinging on the trailing edge of lettering, which various people seem to be encountering with modern-day equipment plugged into C64's.  The URL is 
http://hitmen.c02.at/temp/palstuff/.
Good stuff!!
 
ooroo
Callan
 

Justr linked ya from the

Justr linked ya from the front page and from FB >:)

**blush** - Fame at last!! :D

**blush** - Fame at last!! :D
 
Callan
 

Hey Callan, back in the 80s

Hey Callan, back in the 80s when you were in the scene, were you living in Melbourne?

Scene

ER - yes - I was...  Why?
Callan
 

Was just wondering because I

Was just wondering because I was active in it too. Your name sounds familiar, I wonder if your wife was called Carla and ran a BBS ?
In the day I used the handle Mad Max, was active in the C64, BBS and hacking scene.
Mike.

Takes me back :)

Ya - that's right - Carla (Is) my wife -  I went be the nom-de-plume Deep Image, back then - co-sysop of The Real Connection - later Death... by chocolate. Fidonet 3:632/360.  Carla was "The Real Article".
You lived in Dandenong North for a bit, if I recall - but that's scraping the rust off my grey cells a bit...  we're going back 25+ odd years now.
I just asked Carla - yes, she remembers you too - :) 
Hell, it's a small world :) 
Callan - (or is that Deep!!!)

Aaahh the memories!

I thought so! Reading your initial article a few things began to fire up the ol' synapses, things started to stir in dark and long unused passages of my mind. Hometown SA, 80s hacker, girlfriend into computers, computer engineering and I though, no, could it be.... ?
You're right, I did live in Dandenong North, so the rust must only be surface :) Of course with my parents as I was still at school, my beloved Commodore 64, Skai64 disk drive, First Nice Modem and 1541 disk drive. I loved The Real Connection and you guys were an important part of my youth and a respected icon of the era. An era I remember fondly with both good and bad memories, wouldn't trade any of it though!
Say hello to Carla for me.
Feel free to email me, mikey351 at gmail dot com , would love to continue this conversation on and find out what you guys have been up to.
Mike
Aka
Mad Max

An Intellectual challenge

OK, the board is stripped, and ready for repopulating. 
I now need some help - I need to work out what the 3 14 pin logic chips are, at the bottom of the DolphinDOS board. 
(Pin 1 / the chip notch is AWAY from the 6502 socket  - see the populated image, to get your bearings.
Images (they're hyperlinks - I can't get image embedding to work here, for some reason.
Looking at the TOP side, populated with components.
http://farm8.staticflickr.com/7202/6779509062_57642a8716_b.jpg
 
TOP (Chip side).
http://farm8.staticflickr.com/7193/6989132779_2aa54e4fea_b.jpg
 
UNDERSIDE
http://farm8.staticflickr.com/7038/6989132431_d55cd7c2f9_b.jpg
 
UNDERSIDE-Flipped (Mirror imaged - makes reverse-engineering it easier)
http://farm8.staticflickr.com/7193/6843009070_91788d8a82_b.jpg
 
PDF showing pinouts of the 6502, 6522, 6264 SRAM, and TMS27C256 32K ROM
http://members.westnet.com.au/digitaltapestries/images/dd/Pinouts.pdf
I
've done a lot of research, and have come to this point:, and Wot I've been able to work out with this board, so far is as follows:
The DolphinDOS board has three functions.
1: Maps in 8K Sram (6264) at $8000
2: Maps in 24K ROM, from $A000-FFFF (TMS 27C256), replacing the onboard-20K ROM from $C000-FFFF
3: Extends the 8 I/O lines from port A of VIA #2, to an external cable, to connect the user port of a C64.
 
The 6502 processor, and 6522 VIA are removed from the 1541, and placed in piggyback sockets on the DolphinDOS board. All lines of BOTH chips, EXCEPT A15 of the 6502 are permanently passed-through back to the controller board of the 1541. A15 (Address line 15) of the 6502 is intercepted by means of a 2 way switch. The only reason the 6522 is piggybacked into the DolphinDOS board, is to provide access to the 8 I/O lines for the parallel data interface.
When the DolphinDOS is ENABLED, this address line (A15 - denoting the upper 32K of the 6502 memory map) is intercepted, is NOT passed back to the controller board, but passes to the address decode logic of the DolphinDOS board. A 500Ohm resistor pulls this line LOW on the controller board. This effectively DISABLES the onboard 1541 controller ROM at $C000, and redirects all memory access over $7FFF (32767) to the DolphinDOS board.
When the DolphinDOS is DISABLED, this line is passed back to the controller board of the 1541 - and another 500Ohm resistor pulls the equivalent line LOW on the DolphinDOS board, to keep it from interfering with normal buss access.
Note: the 8-port I/O lines from the 6522 are still connected to the user-port cable, even when DolphinDOS is disabled.
 
Address lines A14 and A13 are used to decode the 32K memory space into 4 8K sections - 0 through 3. The remainder of the address lines are just passed through to the SRAM and EPROM, unprocessed.
When region 0 is accessed, CE (Chip Enable, Pin 20, active LOW) and OE (Output Enable, Pin 22)of the 6264 SRAM is pulled low. If the access is a WRITE, WE (Write Enable, pin 27) is ALSO pulled low. (Note: the WE behavior is surmised, as the chip will not function with CE high, and WE is managed separately to CE - CE and OE are strapped together).
If Regions 1, 2 or 3 are accessed, CE (Chip Enable/powerdown, pin 20. active LOW) is pulled LOW. OE ("G" in TI's nomenclature, Output Enable, active low, pin 22) is strapped to ground.
(I would have though that CE would be strapped low, and OE pulled low for memory access, but what would I know :) :).
Note that the TI27c256 is a 32kx8 ROM - but the low 8K is not used - that region being mapped by the 8K SRAM instead. I wonder if there are any easter eggs in that, on the EPROM - would be interesting to whack it in a burner to read it out :)
 
CAN ANYONE HELP???
 
Ooroo
Callan
 

Some helpful, similar circuits.
The rosetta stone???

FOund a LOGIC diagram for the  DolphinDOS board. It has pinouts marked, but they're wrong for this board (the German author of it probably got it from a clone of the original board... 
It might be a red herring, but it clarifies some queries Ihad (such as "why does it need clock2 from the processor???")
http://farm8.staticflickr.com/7056/6844896356_4fb85d34ce_b.jpg
 
Callan
 

DolphinDOS - the work continues

Well, Progress, of a sort.
By working through all I've found out about the board, and my photos, I've determined that the RIGHTMOST 14 pin IC (nearest the enable/disable switch) is a 74LS08. (Quad 2 input AND gate) - with only 3 used, one gate spare. The inputs, outputs and functions seem to match.
The other two still remain a mystery.
So, reckoning that I had sufficient documentation (photos, etc) of the board, I replaced the decoupling capacitors, and threw sockets back on the board. I also added some header pins on the enable/disable connections, and socketed the DIP header where the 8port I/O port cable is connected.
Underside, with all my bodgy soldering skills on show - (I plan to used flux remover, don't worry) :
Testing started well enough, and then disaster.. the piggyback socketed 6522 blew.  I suspect _MY_ insufficient antistatic precautions is the culprit) - but, inbetween removing and replacing it during testing, it stopped talking to the serial buss. ?Device not present? :( :(
I've replaced it with MY LAST spare 6522, and brought back the drive to life, but I've left the board out whilst I resolve a mechanical problem with the extensions to the CPU/6522 pins. Still, the drive DID initialize , in both DolphinDOS and "compatible" mode.. - and on a drive board that flatly refused to initialize with it plugged into it prior to it's rebuild - so that's encouraging.
 
Looks like time to start trawling Ebay for some more donor gear.
I'm flat out on business for the next few days - having time to partake of my favorite hobby might have to take a back seat :(:(
I thought being retired meant being able to relax and take things easy - It's all a LIE I tell you... 
Oh, hear back from Jim Brain, from Retro Innnovations - he reckons it might be a timing issue, and is burning some different Eproms to get aroundmy C128 JiffyDOS problem. Awesome service. 
Ooroo
Callan
 

Yay - got embedded images

Yay - got embedded images (kinda) working - had to switch to ""Full HTML" for it to work properly..  Now it's only broken if I go back to edit the message - the text box is empty.. (I suspect that may be an OPERA specific problem)
 
Callan
 

ARRGH - a hackers' work is never done

Woke up this morning - staggered into the den, only to hear the squeals of a fan in it's death throes. Turned out it was the cooling fan for the power supply for our Dell home fileserver (runs Windows Home server. ) which holds all our (digital) worldly goods....
Bugger, thort I, I'll just crack it open, pop the fan apart, clean and re-lube it, and it'll be fine.
 
Nope - Firstly - the fan wouldn't pull apart - SECONDLY, while the PSU is apart, I notice... failed and  BULGING CAPACITORS..
 
DOUBLE BUGGER. I've a skedload of stuff to be done today - don't have time for this.  So I crack out the soldering iron, rip out the caps, jump in the car and tear down to the local electronics store, pick up replacement caps & fan, get home, whack in the caps, fit the fan, mod the PSU to make the fan detachable (it was soldered to the board) - slam the lid on the PSU, plug everything in, refit it to the case, , put the fileserver back in it's "rack" - plug it in, and, -fingers crossed- ..... turn it on.
 
Came up just like a bought one -  as my wife Carla is my witness - all inside 2 hours (I kid you not!). 
Amazing what one can do when in a desperate hurry. Managed to get (almost ) everything I needed to do, done, despite this delay, too - so a win!
 
Not Commodore  related in any way, but shows what one can be done in a hurry, and with a soldering iron. 
 
Ooroo
Callan
(posted on FB)
 

YAYY - a possible solution

I've been asking around, and a user (klightspeed)  on a site I frequent - Overclockers Australia - has come up with a possible solution.

http://forums.overclockers.com.au/showpost.php?p=14206460&postcount=16

The board:

 

Underside (reversed)

 

Going Left to Right.. 

IC1 (left) is a quad OR gate - a 74LS32

IC2 (centre) is a hex NOT gate - a 74LS04

IC3 (right) is a quad AND gate - a 74LS08

I'll try it out over the weekend, or early next week :)

His explanation seems quite convincing.

 

Ooroo

Callan

 

 

 

Progress??????

Despite my very busy business this week, I've snuck in some time to work on this beasty..
The "mechanical" problem I referred to was the difficulty in getting a solid mechanical connection between the machined-pin socket for the 6522, and the first of the sockets UNDERNEATH the board. The replacement socket has slightly shorter pins that the original, and this caused problem with the underside socket failing to make good contact.
After trying several different solutions, the only one that was both sturdy, and electrically reliable was to break apart a machine-pin socket (thus releasing all the individual pins) and SWEAT them on - one by one - with solder, onto the pins that pass through the circuit board of the PCB. Man that was a fiddly job.

 

What made it worse, was that the board has no solder mask  - and as traces ran BETWEEN the pins in a lot of cases, preventing solder bridges was a major pain. In one case, it proved impossible, so I resorted to cutting and lifting the track, and replaced it with a trace of wirewrap wire. That's the red wire you see in the image below.

 

Full resolution at http://farm8.staticflickr.com/7096/6867603402_343892c57e_o.jpg

 

As you can see, tracks thread their way between the pins, and, without a solder mask, sweating these pins on was a nightmare. in One case, it was IMPOSSIBLE to do without forming (or risking) solder bridges, so I lifted the track from the board, and replaced it with a wire bridge, (using wire-wrap wire) That is the small red wire you see in the image.

This work completed, I populated the board, and fitted it to my "main" 1541" The drive initialised (POST completed - this was something that was not happening before on this, my "Main" 1541)  

 

Then: - "Device not present"

/cry

 

'twas late - so I left it.

 

TONIGHT:

 

Tonight, - I once again, took the horse by the reins, and started problem solving.

The FIRST thing I did was to move the DolphinDOS across to my spare drive - where it WORKED..
Suspicion turned to the controller board of my drive. - I installed the DDos board back in my drive, where it, once again, initialised, but once again reported "Device not present".

Smelling a rat, I cracked out my 1541 circuit diagram, and started metering out the 6522 pins > 7406/74LS14 connections - and, sure enough - not all of them were making it there....

(much) Swearing followed.

After pulling the DolphinDOS board, I measured out the pins from both sides of the DolphinDOS board - all good.

I ripped out the drive controller board, and desoldered/replaced the (single-wipe) 6502 and 6522 sockets with machined pin sockets.

It was tricky to align the dolphinDOS board pins (all 80 of them) with the smaller targets of the holes, but the board eventually slid into place...

 

The drive came up, and now responds to commands.

Testing is still showing some thermal vaguarity, but we're NOW down the 74LS chips (which we NOW know) - and, conceivably an EPROM.  I'll be ordering the 74LS chips, and post back my results.

Bloody hell, this one ain't going down easy :)

 

Callan

 

 

 

Chips ordered

Chips were ordered from element14 today (cute name) - along with other bits and bobs, and some spares -  They're all in stock, so shouldn't take long. 
 
My uIEC was shipped yesterday - that'll be another fun thing to play with :)
 
Oh, Mike - finally sent you an email!!
 
Ooroo
Callan

The sweet taste of victory....

Klightspeed was on the money. The chips arrived this morning, and this afternoon, time came available to drop them in...

 

 

Note the improved (and much shortened) connector for the enable/disable switch.  I hadn't connected the parallel data cable when the photo was taken.

 

With the new chips in place, the drive was powered up - and it all worked :)

After initial testing, I left it to heat-soak for a few hours, and  - try as I might - could not get it to fail. Finally, I connected the parallel cable, and swapped my jiffyDOS rom out of my C64, for the dolphinDOS ROM - and it all worked just fine :)

So, I am much relieved..  I must confess I was starting to get a little fearful that I might never get this board going again - but despite my very average soldering, the board is working once more. I've learned a heap in the process, too - more about address decoding than I'd ever known before, and a fair fistful about DolphinDOS operation, too. 

 

So, all in all, a great experience, if an exasperating one.

 

Next up - Back to my original task - improving C128 / C64 video output. I've  most of the bits to make the video splitter / amplifier board, so I'll start on that over the next few days.. Shall be most interesting.

 

Ooroo

 

Callan

 

 

 

A Quiet week at Chez Callan

Not too much on the Commdore front this week. I've been flat out on business matters , (and clocking up the frequent-driver miles in the car).. , and, to be honest, have been enjoying the fruits of labour with the DolphinDOS repairs.. and playing games with the C64 :D
 
I've started work on a video board circuit (shamelessly stolen from the Germans) - one which intercepts the video prior to it's manglement by the RF modulator, and correctly "lifts and separates" the signals appropriately for a clean Svideo output.  Pikkies once there's something sensible to show.  I'm looking forwards to getting it going - as it's directly applicable both to the C64 AND the C128.. and it was the C128 that originally sparked the search for answers that brought me to this place.
 
I've been having some fun messing with the native C128 mode - the MMU has me intrigued..  It seems clumsy and  under-implemented (IE a lot of un-implemented capability) - but I also profess to be a total nonce on the C128 generally, and speaking largely from a position of confessed ignorance.
 
If Bil's reading - Why was the 6551 not an obvious inclusion in the C128?- Bit-banging RS-232 is (and was) - positively Neanderthal. The C64 maintained virtual 6551 registers in low-memory ($0293+), so the idea must have been there...
(is "manglement" a real word - if it isn't, it sure should be :D)
 
Callan
 
 

Jack is dead..

Sad news for the computing world - Jack Tramiel has died, aged 83.
 
http://www.forbes.com/sites/davidthier/2012/04/09/computer-legend-and-ga...
 
Thanks Jack - for saving MOS, and creating the company that introduced me into the computing world - and gave me such a wonderful career.
 
Callan
 

First C128 MOD

Well, With the DolphinDOS now fixed, I've been spending a lot of time just "enjoying" my C64. Funny, I don't seem to spend much time playing games - it must be the systems engineer in me - but I just enjoy getting the machine to "do things".
Case in point - I dusted off a program I wrote in - oh about 1989 - which found the start and end address of a program. I cleaned it up a tad, and finally documented it. :)
http://members.westnet.com.au/digitaltapestries/c64/load-address.d64
 
Documentation: 
http://members.westnet.com.au/digitaltapestries/misc/load-address.html

 

To speed things up, I 'd written a hybrid BASIC / Machine language program. The basic did all the messy string handling, and uploaded the machine language code into the disk drive itself,. The drive code read the file, and counted the sectors (and read the tail sector information for the byte count in the last sector)
It was kinda fun going back to that, and remembering how I did it. I was quite ticked to see that it worked, unmodified, on my C128D. 
 
I purchased a set of JiffyDOS ROMS for my C128D from Retro Innovations, run by Jim Brain. I'd fitted a set of the ROMS for my C64/1541, whilst I was working on the DOlphinDOS repair - now that's complete, it's not used much on that platform - but a set now resides in my C128D. With BURST mode in 128MODE, it's not really needed, but the dos wedge is handy, and it sure is a boon in the C64 mode. Initially there was a timing problem that caused the C128 (in 128mode) to drop to debug randomly,  but Jim obligingly sent out a new set of EPROMS (as opposed to eeproms), and that fixed the problem. 
 
I'm back cracking again- once again, it's a fun intellectual excercise, and it's good to know how much I remember. If only I had more time!!!!!
 
I located my B128, and 8250 drive in storage the other day. The B128 is in need of some retrobrite-ing, but seems otherwise intact. I fear tho, that I'm going to need some serious wife-bribery before I can bring them into the apartment :(
Ah well.. 
 
Ooroo
Callan
 

Recent activities :)

I've been having a lot of fun with a fascinating device, courtesy of Jim Brain, of Retro Innovations. Retro innovations runs a site dedicated to solving the problems of using Old CBM equipment in the modern era (Zoomfloppy - interfacing Commodore disk drives with windows/USB2 interfaces being a prime example), and also making fantastic NEW devices using current technology, to work with old Commodore kit.

 

One such device is the μIEC/SD device. Imagine a 1581 disk drive, in solid state, (using SD cards), chipped with JiffyDOS. Make it smaller than the size of a credit card, and flog it for $50.00. In a word, it's AWESOME!.

 

After playing around with it, bare, I decided to mount it,PROPERLY in an external case. Coming from an engineering background, I DO have standards, and lad out some ground rules for myself before starting out.

1: No glue - PCB's are SCREWED in place. 

2: It had to be fully external, and discrete (IE, not mounted in a C64 case - can be moved from  machine to machine.)

3: The case had to look good, and be of a scale commensurate with the unit itself, and it's stamp-sized media.

4: The case had to be able to be disassembled, and all components removed without de-soldering anything.

 

I came pretty close to this in the finished products.  

All PCB's are screwed in place, (using plastic screws and standoffs to avoid short circuits) The only (hotmelt) glue was to effect a minor repair to the plastic mounting rivets to a case component. 

It's fully discrete (standalone) - the IEC connection is via a female IEC, connected to a short "tail". A wire off this tail currently provides power via the cassette port - I plan to clean it up, and power it via a cheap USB 5V plugpack.

It looks awesome (IMHO) - and is a great size. and the case can be split, and (almost) all components removed without resorting to desoldering.

A worklog will be posted later, but here's a teaser pic.

 

Callan

 

Always rely on your instincts...

I made a beautiful serial IEC cable today - the soldering was magnificent, with all the wires properly sweated into the solder pots of the connector, no cold joints, cord anchorage and strain relief neatly done, not too long, and I EVEN remembered to slide the rubber covers onto the cable before starting (hands up who's forgotten that at least once in their electronic career :)
But it didn't work. WHY? - I let my "she'll be right, it's only a low frequency signal" attitude override my knowledge, and I used a UTP Cat5e  Ethernet cable. Yup.. using a twisted-pair cable designed for balanced signals, on a Single-ended signal. 
 
Directly connected between my μIEC/SD and the C64, it worked OK, but when daisy-chained off a 1541 drive, whenever the drive not powered, the combined length corrupted data. (looked like ringing). 
Checking the error channel should return: 00,  OK,00,00
I was getting "00,     OOK, 00,00"
Or other similar corruptions.
Using a SPARE IEC cable worked fine.
I've read elsewhere that the μIEC/SD is a bit finniky about sharing the IEC buss with other devices, and I guess this just proves it. Still, my bad, for taking a shortcut.
 
Ah well - gave me some soldering practice... 
 
Callan
 

Quietening a C128D

I've been working on my C128D in the past few days.

Unlike the (Metal Cased) C128DCR, the C128D has a cooling fan fitted to the power supply, and being a moving part, over the years the bearings have failed, making it rattly and noisy. 

 

I like my Commodore gear  quiet, and the fan (placed as it was right at the FRONT of the unit)  was very intrusive... So I hatched me a plan: Replace the existing fan with a higher displacement unit (most fans now are) , Mount it using vibration-adsorbing rubber mounts, - and then throttle it down a bit using a resistor. 

 

 

The case was opened, the 1571 drive controller detached and the Power supply was removed from the case. Not the very small blades - very little airflow. Also note that the fan is securely bolted to the metal power supply case with 4 stout screws - ensuring every little bit of vibration is transmitted to the case......

 

 

Off with the old fan, drill out the threaded holes to accomodate the new fan, de-burr them, and start popping on the rubber vibration-mounts.

 

Now, going of the rated current, and doing a bit of maths with Ohm's Law, I reckoned that 60 Ohms would give me about a 4V drop. To make sure I wasn't going to cook the resistors, I used 2x120Ω in parallel. I was close - 4.5V drop - that could well be due to non-linear behavior of the fan, or dodgy figures on ratings sticker. In any event, there was still more airflow than with the original fan. More importantly, the fan is now completely silent. 

 

Finally, screw it all together, and enjoy the SILENCE - all bar the workman-like click and whirr of the 1571 drive, which adds to the atmosphere :)

 

'Twas a little project, but one with a great outcome.

 

Callan

 

C64 PSU shennanegans.

It's just as well I worked on my C128 power supply  - (it's lovely and quiet now, but still moves quite sufficient air to keep everything nice and cool!) - as, a week later, my C64 was knocked out of action. /CRY!

 

Matters started out innocently enough - A complete power down, whilst my den of iniquity - er - office - was rearranged. My Commodore gear now (rightly) has a desk all to itself, and dedicated UPS's to boot. The cable jungle was tamed, and I merrily went about plugging everything back in. Suddenly vast torrents of foul smoke started pouring forth from my C64 power supply.. FUCK! - I turned off the power at the wall (Australian power points have switches on them).

No change  - smoke continued to pour out (it's amazing just how much!) then the reassuring beep of the UPS alerted me to my mistake.. BUGGER..   I ripped out the C64 PSU plug from the UPS circuit, and the smoke machine abated.  

I finished off my wiring, and turned my attention to the smouldering remnants of the PSU, all the while thanking my lucky stars the C64 was turned off at the time.

What I saw wasn't pretty. Both rectification diodes were toast, PCB tracks had burned and lifted, and the melamine circuit board itself was charred. This was, as John Cleese would say - an EX Power supply, it has ceased to be... 

 

 

Obviously damaged beyond repair - I didn't even feel I could trust the transformer after shovelling that much current (the insulation was blistered on the transformer wires leading to the PCB!!!!).. There was nothing for it, but to build a new power supply from scratch. (I wasn't interested in sourcing another C64 power supply - they are notoriously unreliable, and prone to overvoltage.)

Minimum specs are 5VDC 1.5A, 9VAC 1A. I wanted to keep the authenticty of the Power supply, so anything I made would have to fit within the confines of the original PSU case, but considering how far electronics has advanced, I didn't see that as a problem. 

I had read various reports of C64 power supplies being made from a standalone 9VAC transformer, and a 5V wall-wart power supply, so I set about doing just that. A 9V 15VA transformer was procured, and a 3A wall wart purchased. I soon changed my mind, though, when I dremeled open the case, and had a look inside... 

There were no MOV's for surge protection, PCB and soldering quality was very poor, and thin tape was all that was being used for  insulation between several active components. It all looked cheap, nasty and possibly dangerous - so that idea was scrapped. Instead, a quick visit to ELEMENT14 produced THIS SUCKER.

5V at 3A, excellent ripple/stability figures, with over-voltage and over-load protection, and nice mouning holes. It looked a lot better built, and much more suitable. After FAR TOO LONG (nearly 2 weeks) - it arrived, and I spent last night building my new, sooper dooper power supply.

After dremeling out various internal brackets and channels, I bolted in the new transformer. Although multi-tap (it was all I could find at the local,) it was significantly smaller than the original. Two holes were drilled in a bracket to allow the primary input wires to be fed out, and NYLOC nuts were used, to make sure there was no chance a nut could work loose and float around and short anything out.

 

 

Next, VERY CAREFULLY, mounting holes were drilled in the base of the case, to take the standoffs for the 5V power supply. Only 3 could be drilled (the fourth was in a grille that was too thin to take a hole - I hot-melt-glue secured that one it in place.)  5V takeoffs, 240V input leads were soldered to the PCB of the 5V PSU board, and the board was mounted. (Note: a cardboard shield was placed under the PCB, to protect the bare underside of the PCB against accidental shorts from underneath!)

 

 

Everything was then wired up. PARTICULAR attention was taken to double-shrink-wrap the 240V wires, for maximum safety. I wanted to fit an internal fuse, but the only carrier I had was not suitable. I plan to put an inline fuse in on the AC input line, or plug, as soon as practicable. The old PSU was not fused either, but the manner in which it failed shows it should have been!!!.

 

Finally, After a power up and voltage test, I hooked it up to my C64, and threw the switch.. SUCCESS!!!!!

After a quick play, to see that things like the Sound worked (the SID gets it's 12V from the 9VAC, and shows up any noise),  I closed-out and cased-up the PSU - job done!!

 

 

So, My C64 lives to play again!!!! - WOOHOOO!!

 

Ooroo

Callan

 

(as always, These photos, and many more, can be found HERE, on my flickr site.)

 

Shenanigans appreciated!!
Mate, thank you for posting this. I'm in the process of sorting out my c64 power supply. Locally sourced an identical transformer, 5v board is a different story. Again, thanks !!
Glad I could help :)
Glad I could help :)
Back from Hiatus

Boy life has a way of getting in the way of hobbies sometimes.. 
Madly busy with protests to a development next door, restructuring the Callan investment portfolio  (which keeps him and his lovely wife Carla fed, clothed and housed), a prolonged visit interstate, to attend to mum, who had a hip replaced, (all going well, she's making a miraculous recovery). Body corporate business scavenges away at my free time and so Commodore time is crimped :(  
 
I have not been idle,however.  I scored an Amiga 500 a month ago, thrown a parallel port mod in my second 1541 (for data transfers from the Internet, via a ZoomFloppy), retrieved a PET 8296 and D8250LP from storage, recovered an ISEPIC freezing cartridge, read up on C128 architecture, put an IEEE-488 connector on the Zoomfloppy (gotta get an IEEE cable tho, only have the PET edge connector - IEEE cable), had a (failed) bash at an Amiga>1081 monitor cable (SCART), and an equally failed attempt at a video enhancement circuit for the C64. (Can't win'em all!!)
Much to post here - as I get time..
 
Callan

NEW PROJECT! - CBM8296 repair

I'm finally fighting free of my work commitments, and have embarked on a new project. 

Many, MANY years ago, a client of my former workplace was throwing out it's Commodore gear. Even 18 years ago I recognised the (historic) value of the kit, and managed to pursuade them to "donate" the kit to me. The kit consisted of:

A CBM 8296
D9090 hard drive
8250LP dual drive
Steel-cased 2001 (late-ish)
4040 disk drive

Various interfaces, including an IEEE-488 modem, & Centronix interface.

A lot of it is stil in storage, but I've retrieved the 8296, and 8250LP drive. Although they were both known to be working when in storage, time will not have been kind to them, and the storage conditions, whilst dry - were far from ideal. In the main they appear intact, but the ENTER key somehow broke off the keyboard. (I found the key, and it's spring, fortunately).

 

Now, I'm not going to power the thing up until I've replaced the critical electrolytics - 18 summers of 38 degree Celsius will not have been kind to them - and gotta repair the keyboard. The drives, also, need some TLC. I WILL say that the 8250LP chassis is the sweetest-designed chassis I've seen in a long time - VERYpretty.

 

The screen has some slight burn-in - but, hey, can't complain too much. I'm more concerned about the PLA.......

 

Anyhoo - for now, just some pictures of the unit.

 

 

 

 

Ooroo

Callan

 

The 8250LP disc drive

I pulled up the 8250LP dual disc drive this afternoon. Seriously, it's a nice bit of industrial design. 

 

Anyway, I pulled off the cover, to check on it's condition - which was on the whole - excellent. 

 

This PCB is powered by a pretty brutish PSU.

 

 

Against my better judgment, and best practice - I powered the unit on - and it POSTS perfectly - WOOT!!!

I'm missing an IEEE-488 > IEEE-488 cable to test it with Jim Brain's fabulous "Zoomfloppy" device (a smart interface that works between Commodore serial and IEEE-488 peripherals, and USB) - but this is an excellent beginning. 

I DO have concerns about the condition of the R/W heads, and head carriage rails. there is some fine surface corrosion on the metal chassis - and this corrosion may carry over to the drives themselves - but I don't want to pull the drives out if I can avoid it - it looks like that would be an absolute SHIT of a job.

 

I've collected a shopping list of caps to order through Element14, so my next job is to get an IEEE cable from Jim Brain, and the caps from Element14/ Mercifully, I have an IEEE>PET edge connector cable - they're as rare as rocking-horse shit, apparently.

 

All in all, a satisfactory day. After ordering bits, I strip the keyboard, and work out how to repair the ENTER key. That'll be MOST - er - character building, methinks.

 

Callan

 

The PSU pic looks like geek

The PSU pic looks like geek art. Looks to be in great condition to boot.

u

Well, time is short at Chez Callan, with a full-house renovations in the finale throes, and a busy time in business - but time was finally found to tackle the broken keyboard.

It seems an accident in storage had clean snapped off the ENTER key. Fortunately, some fishing around in the box rescued bot the keytop, and return spring, and I carefully bagged them with the unit - but how to repair?

 

CBM 8296 detachable keyboard.

 

First order of the day was to pull it apart, which was very straightforwards. Once naked, the mechanism bore an uncanny resemblance to the mitsumi keyboard action used in the first 1982/1983 Commodore 64's - and I smiled. Minutes later, I'd dived into my parts bin, and plucked out a part-out spare C64 from that vintage. 

 

Once I removed the back cover of the keyboards, I knew I was on a winner - the keyboard shaft, plunger and contact component was IDENTICAL - WOOT. I selected a suitable (little-used) key, popped it off from the shaft, and pulled it through from the other side. I then removed the keyboard plunger from the 8296 keyboard, and replaced it with the C64 equivalent.

Broken Key:

Broken key from 8296

 

C64 key shaft installed in CBM8296 keyboard.. (it's the one on the LEFT, with the greenish insert:

 

With the spring installed, and the ENTER key (broken bit removed) pressed onto the shaft, it looked PERFECT.. I prepared to crack out the isopropyl alcohol, and clean all the conductive rubber contacts, and contact backplate ready before assembly, when a little voice whispered in the back of my head.. "Check the conductivity of the rubber"

You see - I had heard of the black rubber contacts becoming non-conductive over time - so I cracked out my trusty  $12 Tandy digital multimeter, and measured the resistance of the (replacement) C64 contact.

 

3Meg-ohm.. 

Damn.

 

Well, I measured the surrounding 8296 keypads - they were about 150 ohms or so - a bit high, but serviceable. Nothing for it, but to REMOVE the key shaft, and replace the silicone / rubber composite insert  with the 8296 one from the broken key. 

Keytop, return spring, and contact rubbers.

FINALLY,I reassembled the keyboard, serviced all the rubber contacts, cleaned the backplate/Contact plate, and reassembled the keyboard. Does it work??? Dunno - Once the capacitors arrive, and I've thrown them in the 8296 mainboard, we'll find out...

Keyboard backplane (Closeup) - shows gold-plated contacts

Keyboard Backplane

 

Repaired keyboard - ready to be fitted back in the case!

Repaired Keyboard.

 

So, all in all, a productive couple of hours.

 

Callan

 

better pikkies

Note: the web page seems to chop off the images.. 
They can be seen, in all their glory - at http://www.flickr.com/photos/12745816@N04/sets/72157631690467740/
 
Callan
 

Back to work :)

Man this thing called Real Life tends to interfere with one's passions.

 

Still, I have NOT been idle.

I have full provenance of the PET 8296 that I've been working on, and I know it earned it's keep in a busy patent attorney's office for the first 11 years of it's life, and was subsequently stored in a not-very-friendly storage location - and as a result the electrolytics are likely dried out, with pretty heavy ESR's, and a prediliction for going bang... so they have to be replaced.

So, I did an audit of the electrolytics in both the monitor, and the PET logic board, and put in a bulk order at Element14.  - a MONTH, three deliveries, two phone calls and a SHITLOAD of paperwork later, they all arrived. I remember at one stage getting exasperated with the poor lass at E14, exclaiming "It's just a bunch of electrolytics - it's not a bulk parts order for a block1 PNGS for Apollo7". 

I guess I showed my age rather, there :)

 

AAANYway, all the caps eventually arrived, and tonight I re-capped the logic board. Despite the NEW caps being about %30 smaller than the old ones, they don't look out of place. IN the next few days I'll re-cap the monitor (which is a significantly trickier proposition - and I'm not looking forwards to realigning the blasted thing afterwards) - and then powering up the thing, and praying that no smoke leaks out :)

 

a couple of pikkies:

 

The paperwork from Element14, as checked by a curious Russian Blue cat, Artie:

 

Paperwork for a kit of caps

 

 

And the 8296 board - recapped. (I didn't replace the ceramics - I reckon they'd have lasted the distance)

Re-capped 8296 PET mainboard

Callan

 

Yeah ceramics are probably

Yeah ceramics are probably okay.  Lol... the last time I went to but Alum Elec's they were easy to get and I assume the low voltage ones still are.  Are the one you do get as you mentioned need to be carefully powered up or anytging due to age?  I.E> are they new-old caps or new caps? 

Love the decdication to the craft!
 
Bil 

Eeep  - sorry, didn't notice

Eeep  - sorry, didn't notice the reply.
No, they're all new caps, not "New old Caps". The only one that's caused me angst has been the big 10,000 microfarad power filter one. I was concerned as the one it replaces had 4 electrical contacts on it. I was a little concerned that it might have been a funny electrolytic that had 2 positive connections (IE 2 electrolytics back<>back) - like you occasionally see in speaker crossovers - but a check with zimmers confirmed it was  just a phatt smoothing capacitor for the main voltage rail.  The other two contacts are just there for mechanical support. 
I plan to re-cap the ones in the monitor tomorrow, time permitting. Had a small family disaster with mum smacking her head open in a fall, and bleeding like a stuck pig :( :( -  After a short stint in hospital she seems OK,but it was all quite a scare.
 
The reason I embarked on replacing the electrolytics is because of the hard life I know they had when operating, and the even harder life they've had in storage. There are a lot of components in the machine that are just not obtainable now, that I didn't want killed by antiquated electrolytics. (I'm chatting with an aquaintance who's lost a C128D due to a PSU explosion - hopefully it's resurrectable).. 
 
Callan
 
 
 

Kid in a Lolly shop

Well, I've struck a problem recapping the CRT board for the 8296. One cap seems to be rare as rocking-horse shit - a 12uF 25V. Once I have that one, I'm set - but none of the usual suspects actually STOCK them. - GRRR. I might have better luck getting a tantalum replacement - looking into that atm.

 

However! - I'd been negotiating a fellow who had a "Barn Find" of a pile of Commodore gear - and last Monday, I received a shipment of 40Kilograms of Commodore kit.

Some of it was tested and working.  Some of it was unknown, some if it was suspect, and some was definitely stuffed. 

 

 

 

 

All the C64's work, but  the Breadbox shows signs of a major rework  all RAM chips, one 6526 and the RAM multiplexers have all been replaced - my guess would be a power supply overvoltage. Since it's the only one of the three with a "doorstop" power supply, that wouldn't be surprising. The badly yellowed C64C is a "standard" board, but the non-yellowed unit (with the funny keys) is a CR board, with the enhanced PLA (with incorporated colour memory). It also has a noiser video output.

The Disk drives - Ahh.. the disk drives.

 

The VC2 is an MSD-SD2 drive. The second drive is flakey it seems (most likely fromthe bash it has obviously received) - but I haven't had much of a chance to diagnose it. Other than that, works fine, both on serial and IEEE. 

The two cream-faced disk drives are NOT 1541C's - but normal Panasonic mechanism drives with 1541 boards. The TOP drive suffered from "serial buss lockup"  - IE any access to the drive locks up the serial buss. ONLY after replacing the 7406 hex buffer and 74LS14 schmit triggers (the most likely culprits) did it become clear it was in fact the 6522 chip itself was stuffed.. Since the board is COMPLETELY unsocketed, this was most aggravating. Working fine now.

The middle drive (which looks like an antique drive, albeit with a lever mechanism) had been dropped on its face as a child, damaging the latch mechanism (inside and out). Once the latch mechanism was replaced from a donor drive I had lying around, it transpired that the DRIVE controller 6522 was stuffed. Despite all appearances, this is in fact a1541C drive, in a much older, 1984 case. However, the board was socketed, and with a spare 6522 (thoughtfully amongst my shipment of goodies!) - this drive, too was restore to health.

the bottom, cream drive with a switch works fine. The front switch is a drive-ID mod. One note though - the board has had some repairs done to it,  by the looks of it - by Stevie Wonder. Cold joints and insufficient solder abound, and I'll need to rework it a bit to keep it reliable. 

 

And now we come to the poor beleaguered 1571.

It WAS working fine when the vendor tested it, only for it to go "BANG!" before he turned it off. I bought it anyway, at a reduced price.

 

Once it arrived here, the fault was soon aparrent - the mains power receptacle had adsorbed moisture, and when warmed, bulged badly, shorted, and fountained yellow powder everywhere. I replaced it with a spare - but still, NO power.

I bought in from Element14 a suitable dual-rail micro-PSU, and went about replacing the PSU board, but as soon as I removed it, I noticed that ALL the solder joints for the voltage regulators (and the transformer) had fractured. I reworked the board, plugged it in - and Hey Hey, up it came - WOOHOO!!!!

 

My joy was short lived...

 

Grabbing a TPUG C128 utility disk (I had it to hand) - I popped it in, latched it, and my blood ran cold, as  a mechanical shaving noise eminated... 

Yes folks - as is so often the case, the top r/w head had been damaged in transit (despite the shipping piece!) - and had shaved a nice lot of media off the disk   /cry.

A new R/W head assembly (yes you CAN still get them!) is now being organised...... I'll beat this bugger yet. More than a little sad about losing the TPUG disk, though.. 

 

There's still more fun to be had - a C64 IEEE-488 adapter, an IEC serial>Centronix interface, some tape drives and some oldie-but-goodie 6502 books.. 

 

So a fun, if exasperating time!

 

Ooroo

Callan

 

Where has Callan been???

 

Good God - has it been three months since I posted??? Crikey.

Well, Callan has been a busy man, and sadly deprived of his Commodore kit for a short while. It's back, and I'm happily getting back into the swing of things. - You see, it all started when Carla, his wife decided it was time the Den was overdue to be renovated. She was right as usual. It took longer, and cost FAR more than it should have - as usual - but the results are worth it. (or so I keep telling myself)

All of this necessitated us being "moved" out of the den into our library, for the duration, and packing away in storage all my Commodore gear. It's all now back, and I've been getting some time at it, but it was a most traumatic experience.

The plan was to get rid of all our desks, and replace them with wall>wall benches, made from "Caesarstone" sort of synthetic stone commonly used as kitchen benchtops. As many bookshelves as possible, in solid ash, (as in the library), wheeled drawers which fitted under the benches, and cable trays under the benches, to get rid of the many "dangly cables" 

The room before:

 

 

The two big desks were donated to aquaintances, and the gorgeous walnut desk temporarily in storage. then the place was gutted, and the new bespoke desks and bookshelves put in. Finally, the curtains were retired, the walls repainted, and a new honeycomb cell blind installed.

Installing the computer gear took about 2 days all up (!) - but the result is as below:

 

and of course, my precious Commodore kit. I haven't put the C128 back - that's a few days away.

 

A trip to storage is planned next week, to collect our remaining books - they now have a place to live - YAY!!!!.

 

I've done some trivial hardware work - I've encased my wonderful JiffyDOS interface (now with a functioning IEEE-488 interface that I've used to test my 8250LP disk drive), and made some IEC serial cables (using NON-twisted cables this time - no data corruptions - YAY!), and a chunk of work on my CBM8296. It's now been powered up - with no life :( - (it looks like a PSU problem) - It's to be worked on again shortly, when I can commit to a good few clear days. I desperately want it working again.

We've also been running around looking for an investment property, filing tax returns,  and, in the infinite spare time, playing World of Warcraft, and RIFT.

 

Oh, and a wonderful, sweet Commodore 64 game - "Below The Root". It's a gentle "storytelling" game, and a delight to play.

Callan

 

Cool.  The favorite games

Cool. 
The favorite games back at CBM were a mixture of Jump Man, the driving game in case you already were burnt and drooling and just needed a single control to twist, and I used to play Kennedy Approach on days when I felt I hadn't had enough pressure already.  The pilot would radio you to tell you they were going down if you flew them into a mountain and if you hadnt had any sleep that night you could hear crashing metal and screams in the background of the transmission. >:)
Bil

Hehe. Sending planes into

Hehe. Sending planes into mountains - that's as evil as my wife playing the Sims, putting all the sims in the pool, then taking away the steps (so they drown!).....
Jumpman was absolutely Awesome - I still play it. There's a similar game called "Wizard" - which is like as much fun today as it was when it came out. Very Jumpman-like, with brilliant sound effects, and a CONSTRUCTION SET!. 
I'm currently backing up all my disks to PC using a Zoomfloppy (a USB><IEC/parallel/IEEE-488 adapter), and coming across many treasures. Spelunker, Space Taxi! - Montezuma's Revenge - Loderuner -  A lot of them can be played now on a μIEC/SD device (disk drive, using SD cards as media  - I use the excellent one from Jim Brain) - and I'm getting a readability strike rate of about %90. Some personal stuff too - letters I wrote using EasyScript back in 1984 - programs I wrote (Including several that ran in the 1541)  
Little known fact - the FIRST version of Easyscript had an easter egg - if you pressed F1 (to get into command mode) and then pressed Control-3 (or was it Shift-control-3 - I can't remember) - it would play "Rule Britannia" - True - I've seen it!
I'm in touch with someone who's come across another "Barn find" (so to speak). Some interesting stuff there - Various Vic's, (including one early japanese-made PET keyboard one (like the one I already have)), some C128D's (plastic case), a 1571 & some 1541's, 1520 printer/plotter. No MPS801 printer though, which I've been after for a while. It's a bit of a drive, - but let's see what happens with negotiations. I really have to get the 8296 running first.
 
Callan
 

Bought some stuff, fixed some stuff.

That fellow who enjoyed a "Barn find" of a lot of early Commodore gear.. After some discussions, a deal was struck (I paid over the odds - no matter) - and collected a PET keyboard VIC, a VIC 1515 printer, a VIC 1010 expander (!), 2 Commodore  1350  mice, a 1541 (for spares), an early VIC tape player (in some distress) to part out for one I'm rebuilding - and a gungy looking 1571 (more later.) All of it has suffered badly from poor storage (most have dead bugs inside!!!!) as you can see - but there are some items of interest there.

The VIC 1515 printer was the first Commodore IEC serial printer made. Based around the Seikosha "Gorilla Banana" (I kid you not!) printer engine, it's literally a "1 pin" printhead. The matrix that makes up the printer is made by a single slanted, hammer - and it is vertically "scanned" by a star-shaped "platten" behind the printer. Weird - REALLY slow - but it works. After the drive repair, this is next to be brought back to life.

The 1010 expansion chassis is a rather rare item - and quite a score. It'll go through a full cleanup in due course.  The VIC20 itself has a bizarre keyboard rewiring - I'll have to look at it later. It's a Japanese built VIC, and in rather poor condition. Salvageable, though. I have a mint-condition PET keyboarded VIC (so early it has an FCC waiver sticker), so I'm in no hurry to restore it to its former glory. It'll get TLC in due course, however, and it's now being safely stored.

The 1571 disk drive is in dire need of a cleanup and retrobrite, and was in filthy condition internally. I re-capped the PSU, as some of the electrolytics were pushing up from the bottom, and had visible corrosion. (subject of a separate post).  

Anyway! - Some pikkies!

VIC20 & my favorite VIC game

VIC 1010 expansion.

 

 

1571 disk drive

 

Callan

 

1571 cleanup

Dud double-post - please delete.
 

1571 cleanup

Despite the dire appearance of the drive (above), I had high hopes for this drive. It was filthy with dust, the top cover was stained, there was a wasp nest blocking one of the screw access holes (!), and a dead spider on the main PCB - but there was no rust anywhere.

After pulling out the power supply, I resolved very quickly not to power it up. Some of the electrolytics were pulling away from the bottom, with obvious pressure building up (though no bowing of the top, oddly).

The drive was disassembled, the PSU was pulled from it's protective cage, and all the electrolytics were pulled and replaced. 

 

BEFORE:

 

AFTER:

 

Then the main controller board was cleaned: (I didn't replace the few electrolytics - none of them would fail catastrophically - perhaps I'll pull them later). 

 

Then the case was given the clean of all cleans, and the drive assembled!. (Compare it with the photo in my previous post!)

 

And it now works a treat!! I've tested it in both single and double-sided mode, and in burst mode using my Zoomfloppy, and it seems quite happy - as am I. After over 12 months looking, I FINALLY have a working 1571 - WOOHOO!

Callan

 

 

 

 

Rummaging through storage today, and I found....

My TED machine.

 

OK - I know Bil considers it an abomination - but, hey! - it's got a TED, 64K RAM, and it has a user port and 6551 UART in it - so It can't be ALL bad :D

I'll have to check it out thoroughly before powering it up. (and check out the power supply - it's a bastardised C64 PSU of dubious vintage...

 

I KNEW the bugger was in there somewhere - I'm pleased to find it!

 

Callan

 

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