Joe's Dolch Colt 300/ Atlas 9600 web page

Revised 11/04//2000

This page still under construction

How it All Began

At the 1999 Jacksonville hamfest I picked up a modular Dolch instrument. It looked like some kind of logic analyzer but what really intrigued me about it was the fact that it was computerized and it had a MP/M operating system. After getting it home I found out that it was made by Dolch Logic Instruments (DLI) in Germany around 1982. I don't know why, but it has two names on it; Colt 300 and Atlas 9600.


The Colt 300 a modular test instrument with a slot under the CRT (picture) to accept plug-in interfaces and judging from the keyboard overlays (picture) on the full size keyboard, there are (were?) logic analyzer, pattern generator, emulator, EPROM burner, serial data analyzer and possibly some other plug-ins for it.. I have the digital pattern generator plug-in and the logic analyzer plug-in for it. Here is a good size picture that shows the instrument and with the pattern generator plug-in. The cables for the pattern generator pods plug into the sockets below the CRT. The Colt 300 has two half height floppy disk drives, a built-in miniature keyboard (close up) and a built-in CRT. I also have the optional full size keyboard (picture) for it. On the back (picture) it has a socket for the cable for the external keyboard. A short jumper is plugged into that socket in order to use the built-in keypad (picture). Below that is a parallel printer port , two RS-232 serial ports and a HP-IB port at the bottom. There is a brightness control, video port and reset button in the center. After I powered it up, I found that it also has an internal RAM disk drive.

The pattern generator that I have is a Dolch model 9648 and it has 48 data channels as well as associated clock, start, stop and sync channels.

The "Inards"

I opened it up and took a look inside. It has 3 Z-80 CPUs and two sections of 256k dynamic RAM. The Z-80s can only address 64k so it divides the 256k into four 64k banks. Each bank can run it's own process but the top 16k of each bank is common to all four banks (only the lower 48k is bank switched). The fixed 16k is used to for part of the operating system. I know 2 x 4 is only 8 but somehow this thing has 16 workspaces in it! Each workspace can pass data to other workspaces by means of a link utility. Any time one the workspace needs to communicate with the console (display and/or keyboard) it illuminates a little indicator on the top of the screen. You can use one of the special keys on the keyboard to switch the console to different work spaces, almost exactly the same as Windows but running on a 1982 vintage Z-80 system!

Does Anyone Have Manuals for It?

I have no idea how to use the basic instrument or pattern generator or the logic analyzer but even without them this thing is cool. I have contacted Dolch in both the US and Germany and asked about manuals for it. Both say that they still have manuals for it but I have not been able to get any prices from them. They don't appear to be very eager to sell them.

Later. I've finally made some progress figuring out how to get into the programs that control the pattern generator. I noticed that the power up screen (picture) listed a file named SOMA. I had a disk with a program by that name. I had already tried to execute the program from the operating system prompt but the program failed saying that it could not find a necessary file. I then found a brief comment on one of the keyboard overlays (picture) that said that the system had to be booted with the disk with the software for the plug in the top drive. OK, I put that disk in the top drive and tried to boot the system. No go, it's not a bootable disk. Fortunately this system lets you boot from either drive so I reset the system and told it to boot from drive B: It did, then I logged into drive A: and tried to execute SOMA. This time it ran longer before it failed. I continued to read the keyboard overlay notes. One of them said that the special function keys along the top of the keyboard could be used to call up any "slot" on the monitor. Ok, the power up screen showed SOMA was connected to slot 2 and F so I pressed the "Slot n" and then the "2" keys. The screen went back to the operating system screen and showed SOMA loading. I kept my fingers crossed and watched as first SOMA, then MV02, MW02, ML02 and all the other files loaded with no errors. After that I can use the other special functions keys to call up the timing (picture), setup, data (picture) and all the other screens that control the pattern generator. This picture shows "slot" 1 and "slot" F pulled up simultaneously. The word "slot" seems to be Dolch's term for process. This system can handle up to sixteen (1 through F) processes simultaneously. The blocks on the right hand side of the screen show programmable function for each of the "soft keys" on the right of the CRT. These are used to change the settings on the various screens. I haven't fooled with the logic analyzer yet but I expect it operates the same way.

The MP/M operating System

It has a complete Digital Research MP/M II operating system (picture) including the assembler, development tools, etc. More details later. Here is a photo of the CRT screen with a CAT of the utility disk (picture)

Disk Format?

Does anyone know what disk format it might use? I tried all of the formats in 22DISK but none of them could read the Dolch disks. When you run the disk format program it shows it formatting 40 tracks. I tried STAT DSK: and it shows;

A: Drive Characteristics
2,048: Byte Record Capacity
256: kilobyte Drive Capacity
64: 32 byte Directory Entries
64: Checked Directory Entries
128: Records / Directory Entry
8: Records / Block
32: Sectors / Track
3: Reserved Tracks

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