The recent discussion on BSC protocol prompted me to dig out my Microvax 3100
with DSH32 synchronous serial interface. It had been idle in storage for
several years and it wouldn't power up, only giving a brief flash on the
diagnostic LEDs and a quick twitch of the fans. There was a slight smell, like
the stale air that comes out of a deflating tyre.
I took out the H7821 power supply and found that five identical brown 1800uF 25V
electrolytic capacitors on the output side had leaked.
The SCSI disk enclosure where the machine's system disk lives required several
power cycles to get it to run at all and it died as soon as the disk tried to
spin up. It turned out to also contain a H7821 power supply which had a
similar issue with the same five brown capacitors, although not as extensive
as in the main unit.
I found a second disk enclosure which had seen little use and grabbed the power
supply out of that to put in the MicroVAX. It worked well enough to test with
but there was a ring of goo around the bottom of one of the brown capacitors
which was worst affected in the other units. Time to order a batch of
replacement capacitors and figure out what else has been damaged. While it is
not the worst I have seen, access to these power supplies for repairs is quite
difficult and it is really difficult to debug them safely while they are
running with the cover off :-(
If anyone has anything with H7821 power supplies in them, I suggest checking
on these capacitors. If anything with these power supplies is in storage, I
suggest ensuring it is stored the normal way up as this should limit the
ability of the goo to escape and spread around the power supply.
And there I was thought I was being safe enough by removing the nicad battery
packs some years ago...
> From: Mattis Lind
> Thanks Noel for sorting this out.
Eh, de nada. But thank you.
>> I wonder if the ucode in the two versions is identical? The uROM chip
>> numbers should give it, (if they are the same on both versions, albeit
>> in different locations on the board), but I have yet to check. Does
>> anyone happen to know?
OK, so the situation here is pretty complicated. To start with / make things
worse, that CPU uses lots of PROMs. Lots and lots and lots and lots of PROMs.
For the data paths board (M7260), both major versions appear to contain the
same PROMs (going by the DEC part numbers), but the chip location (Exx)
numbers are all different.
For the control board (M7261), the C, E ('early' version) and F ('late'
version) etch revisions each contain mostly the same PROMs, but apparently
with slight differences between the sets of PROMs in each (as reflected in
different DEC part numbers). For details see:
to which I have just added all the gory details.
As to getting the contents of all of them dumped in machine-readable form -
>> on the earlier version (prints for that version are in the GT40 prints
It turns out that I have hard-copy prints for the "C" etch revision of the
M7261, which do not yet appear to be online; the GT40 prints have the "E"
I will scan the pages for that revision of the board, and put them up 'soon'.
(I'm not doing the whole print set, it's about 1" thick, and most of them are
for other things anyway, like MM11-L memory, etc.)
> From: Toby Thain
> To get closer I'd need better images of the panels.
Hi, I borrowed a DEC inlay from someone (a KA10 CPU bay) and scanned a chunk
of it (as much as I could fit into my A4 scanner :-) at 200 dpi:
I have a TC08 inlay, but it's currently being used in my QSIC display (until
we can get the RKV11-F/RPV11-D inlay done :-), and I didn't want to yank it
out. As far as I can tell, it's the same font on the two of them.
> the closest I know of off the top of my head is Akzidenz Grotesk.
The Akzidenz Grotesk Medium is indeed very, very close (other than the zero).
Do you happen to know if that font available for use in non-commercial
Since a few days, my EXORciser Development System is finally able to boot from floppy diskettes.
Previous attempts have shown that the Motorola EXORciser M68SFDC1 floppy disk board used has a special modified ROM version. This was probably written for an 8-inch drive, in which the Write protect and Direction signal were inverted.
For the sake of simplicity, I have used free inverter on the board to invert the signals accordingly.
After adjusting the PLL frequency, reads and writes from the card are now error-free. And all without FDC, only clever programming by Motorola software engineers in the early 76?
Originally, the EXORdisk system was a dual drive with two 8 "units. This I have replaced with a double drive of two 5.25 inch units. An Epson and a TEAC, which can be jumpered to 360 rpm. Luckily, 2HD floppy disks are easy to R&W.
I also got a GOTEK floppy emulator running, which I can boot from. Thanks to Roland Huisman, Bitsaver has some interesting floppy disks that convert to HFE format work perfectly. This format makes the Gotek drive most reliable.
Now to my question. The vintage computer forum at http://www.vcfed.org/forum/archive/index.php/t-44638.html mentioned some interesting manuals. Archive.org has some manuals, Bitsaver does not have manuals about the M6800 development system.
If someone already owns scanned manuals to the following list
M6800 Basic Interpreter Reference Manual
M6800 Macro Assembler reference Manual
M68SFDU Exordisk 11/111 Disk `Drive Unit Maintenance Manual
M6800 Exorciser 11 User's Guide
M6800 Exorciser User's Guide
MEX68PP1 PROM Programmer Module Supplement M6800 Exorciser User's Guide
I would welcome any feedback or questions
The famous Brigham Young University 3D graphics program, by Dr. Hank Christensen.
I am looking for the fortran source, it should be 7 files:
Any docs related too.
Thanks for letting me beg.
The past few years I?ve become fairly focused on a particular old 1999/2000 ww2 fps computer game. Of course playing it but I?m also on the development team for the game (EA has given up on it, but we still put out new releases, maps, patches, etc.). As a result of that, I pretty much live on Discord text/audio chat these days. If you send me an email I will eventually see it and may even respond heh. But if you send me anything on Discord I?m going to see it immediately. If any of you are on discord, I am ?Todesengel#9624?. Feel free to add me as a friend and that way you can get me usually immediately. I am not leaving the hobby, nor am I saying not to email me at the usual address. But a lot of you do talk to me semi-frequently and I?m just saying discord will get to me far quicker.
In addition, mostly as an exercise to see how to do it, I set up a ClassicCMP discord server. That Discord server is NOT meant to replace this list, nor should it be taken to signal any less commitment on my part to keeping this list running. They are fundamentally different things; Discord is great for real time text chat back and forth. There are also audio and video channels if people want to use that to talk verbally or via video. To get on that server, here is a semi-permanent invite: https://discord.gg/U8Skw5g Joining the server gets you to all the other folks who may join the classiccmp discord, not just me. Of course, that could be zero ? Like I said, I just did it as an exercise, and discord is how some of my family and friends stay in touch. But it is there if peeps want to use it.
I?d rather not turn this into a long debate of whether discord is good or bad or anything like that. I?m just saying it?s there, and it?s quicker to get ahold of me that way at times.
I have a Naked Mini system that was used as the controller in a Linotype phototypesetting machine. From what I've been told, the Naked Mini CPU board is Nova compatible. I would like to use the CPU board in my own system, but I don't have enough information to do so. I haven't been able to find any documentation online that describes the backplane interface.
I could reverse engineer the backplane using one of the RAM boards as reference, but if the information already exists it would save me a tremendous amount of time.
Here is a gallery of the controller cage: https://imgur.com/a/LNkQisq
On Sun, Jan 19, 2020 at 11:30:31PM +0000, Kevin Parker via cctalk wrote:
> A we're all aware members on this list often dabble with other
> technologies. In my very aggressive cleanup of my hobby space I came
> across a number of U-Matic Video Tapes. If anyone is into this older
> video technology and would like these 8 tapes please contact me off
> list. (They are physically located in the south west of Victoria,
I'm interested in the technology, but I'm on the wrong side of the world to
add these to my collection. I have a few U-Matic tapes, but haven't found a
To make this slightly less off topic, three of the U-Matic tapes I have are
in an SRA Computer Training Library boxed set containing:
MVS Concepts and Facilities - Mini-Course 2 - Introduction to Job
MVS Concepts and Facilities - Mini-Course 5 - MVS System Programs
MVS: JCL Coding - Mini-Course 11 - Requesting Space for DASD Data Sets
I found them in my current employer's document library years ago. Any
player(s) we had were long gone, so I've never seen them.
What's the definition of a legacy system? One that works!
Errare humanum est, ignoscere caninum.