digital group computers - new site launched, and new emulator released

Hi there,

Wanted to let you know that I've launched a new site dedicated to the digital group family of computers, and released a cross-platform digital group emulator.

The site address is http://thedigitalgroup.org

For those not familiar with dg, the digital group was a company based in Denver from approximately 1975-1979.
All of the hardware from dg was designed by Dr. Robert Suding, and was quite advanced for the time. They were among the first to use a ROM for soft boot instead of flipping switches, and allowed switching of CPUs by switching CPU cards.

A fellow named Tom Apel ran a dg site there for some time, but it had gone offline last time I checked, sometime earlier this year, so I decided to take up the reins of preserving the history of these computers.

I have also posted executables (win and mac) for a digital group emulator that I've written. It emulates a dg computer with a Z80 processor, 64k of RAM, 64 or 32 column TV card, cassette interface, and ASCII keyboard. As soon as I have a chance to clean up the source code a bit I will release that as well.

The site and the emulator are both in the early stages of development, so stay tuned for more updates. I welcome any comments you may have to improve either one. Also send me a message if you have any information you want to share about dg systems. Thanks very much!

Interesting. The emulator is interesting as well, I'm waiting for the source code so I can compile it for FreeBSD.

Thanks Torfinn, glad you enjoyed it. Should have more information about the digital group and the source for the emulator up very soon. In the meantime, you could get started by taking a look at Marat Fayzullin's Z80 emulation code (http://fms.komkon.org/). I used this for the Z80 processor emulation.

Hi all, it's been a while since I've posted on the forums.. life has been very busy recently and I haven't had as much time for my vintage computing hobby as I'd like. Although in the last few days, I've been putting up some software projects on github, both to help me organize things, and also to share with others who may be interested.
I've put the full source code for dgemu, my digital group emulator, up on github for all to see and play with.
https://github.com/bitfixer/dgemu
I switched to a new Z80 core for the emulator, z80ex, a GPL licensed z80 emulator also used in some other emulators.
dgemu loads binary files which I have converted from audio tapes of dg software in audio form. It includes a command line utility, suding.php, for conversion from dg software in audio format to raw binary (requires sox, an audio tool, to be installed on your system). Currently I have only an Xcode project file for building on Mac, but plan to include makefiles/project files for building on windows/linux.
Please check it out if you have any interest, and let me know if you have questions. Thanks..
- Mike

Very interesting. For the lazy people (like me), have you thought of doing some screencapture videos of you emulator running Lunar Lander and WoProc, and uploading them to YouTube?

Also, does the digital group computer(s) have a CP/M version available for them? If not, it should be doable building a "BIOS" file to make CP/M run on them, am I right?

What is the second picture on your website?, it looks like 4 cassette drives.

Pepinno said:

Very interesting. For the lazy people (like me), have you thought of doing some screencapture videos of you emulator running Lunar Lander and WoProc, and uploading them to YouTube?

Also, does the digital group computer(s) have a CP/M version available for them? If not, it should be doable building a "BIOS" file to make CP/M run on them, am I right?

Click to expand...

Sure, sounds like a good idea, I can do some screen captures..
The screen output on dg systems used output port 1 from the Z80 to write characters into an output buffer. To clear the screen, you needed to write a full screen of spaces to erase what was there.
As far as I know, there was a CP/M version available for the dg computer, and I am still in search of it. So far I don't have my hands on any disk-based software for dg as of yet. There was also a disk operating system called 'diskmon' which I am looking for. Hopefully dgemu can be extended to include disk emulation as well.

mnbvcxz said:

What is the second picture on your website?, it looks like 4 cassette drives.

Click to expand...

That is a device called the 'phi-deck' - basically a mass storage device which used 4 cassette drives, with drive control from the computer. I'm not sure exactly how the data was striped across the 4 cassettes, but they were reputed to be very difficult to work with. An interesting beast.

Hi, I just tried tried the "dg" emulator for Windows. The program uses 100% of the CPU (userland) in my Windows machine (which currently is a laptop, which puts the fans at full speed, which is noisy), and there seems to be a "white space" just before the blinking cursor, that "white space" goes with the cursor whenever you are in the screen... Is that by design?

I'll take a look, it's been a while since I've run the windows version. It uses the curses library for terminal drawing, which may not be very efficient. In the next iteration I may make an OpenGL window which renders the text exactly as it shows up on the dg, so that may change the CPU load. Stay tuned for more updates when I have some time.. if anyone wants to take a crack at the source code please go ahead. The dg-specific stuff is quite small, most of the work is done by the z80 emulation core.

Hi All;
I have copies of Diskmon ver 3.0.. And maybe of CPM, but they (the CPM) are most likely corrupted, and not readable or at least not bootable, all is on 8" floppies.. There is also a CPM look alike, I think I still have it as well, it was written by Microsoft If I remember correctly...
THANK YOU Marty

Hello All,

I have had DG computers since the start. I have not used them in a long time. I had an 8080 system and later got the Z-80A board with a big metal case and 8" floppies.

In 1977 or 78 I helped a local accountant get a DG system up and running and wrote BASIC programs for his apps. He used the system til he died a few years later. Don't know what happened to the computer. It did his job for him tho.
Using today's computers makes you wonder how 8 bits and 32k ram could do all we needed back then. Maybe we don't need all the overhead we have now.

I've still got two systems. One is my original and one I picked up at a hamfest some years ago.

I remember going to a DG meeting at Dayton hamfest in the 70's and meeting the group from Colorado. To bad it ended so soon.

Bob

Marty said:

Hi All;
I have copies of Diskmon ver 3.0.. And maybe of CPM, but they (the CPM) are most likely corrupted, and not readable or at least not bootable, all is on 8" floppies.. There is also a CPM look alike, I think I still have it as well, it was written by Microsoft If I remember correctly...
THANK YOU Marty

Click to expand...

Did you ever have a chance to dig the disks you have up?

I'm in the process of uploading some material I had access to into
http://bitsavers.org/pdf/digitalGroup and
http://bitsavers.org/bits/DigitalGroup