February 17, 2022

Callan Multibus 68k CPU board - Roms

The board has 4 rom sockets (28 pin) U101 to U104.

U101 and U103 have a pair of 24 pin AM2732 roms.
U102 and U104 have a pair of 28 pin Hitachi 2764 devices.

The labels on the 101/103 pair simply say "Pacific Microsystems".

The labels on the 102/104 pair say "CWC 21MB 02-Mar-83" and have a "Callan" logo.

This would suggest that Callan added a pair of roms with support for their 21M hard drive. In fact the system used a "Rodime" RO200 MFM hard drive (made in Scotland) along with the Callan hard drive controller board.

Reading out those roms

I use a MOD-EMUP prom burner/reader hosted by a crusty old FreeDOS system for things of this sort. It usually sits around for several years between uses, so it will be interesting to see if it boots up and runs.

Actually the first trick is going to be finding it, as it was moved out of the way to make table space. Indeed, it is in another room with things getting piled on top of it. I find a keyboard and monitor, fuss with an eratic power strip, realize that I am using the wrong connector on a dual connector video card, but it does boot up. I am going to record the process since I do it so seldom that I am likely to forget by the next time this sort of thing comes along.

When you see the DOS prompt, type: 

cd emup
access
This gets you running the prom burner software. Select device and find your manufacturer and device. I will start with the 2732 devices from AMD. These are plain 2732, not 2732A devices.
Type "R" to read
Typo "3" to save to disk 
U101 3ACE  callan1.bin 4k
U103 8F42  callan3.bin 4k
U102 1D2E  callan2.bin 8k
U104 9515  callan4.bin 8k
Happily, the 102 and 104 chips have a checksum printed on their label and it matches what my prom burner just got from the read.

Now I have 4 files on disk, but next is the hard part. This FreeDOS machine knows nothing about USB flash sticks. It has a working network, but ssh will no longer interoperate with modern sshd servers due to changes in encryption standards.

This turns out to be easy, although I had entirely forgotten. I just use ftp !! The last time I faced this issue I installed mTCP, which includes an FTP client. I am still running an FTP server on my linux machine (surprisingly enough), so it is a simple matter of: 

ftp 192.168.0.5
mput callan*.*

So, that is it for reading them, making sense of them is another project and something for another page.

Feedback? Questions? Drop me a line!

Tom's Computer Info / tom@mmto.org