Search Posts:

Systems Group System 2900

SHARE

Return to Threads

  Systems Group System 2900 by Bill Degnan - 05/15/2017 21:34
Systems Group System 2900 S-100 Computer
Pictured is a circa 1982/3 Systems Group System 2900 Business class S-100 computer system. Click image for larger view


Systems Group System 2900 S-100 Computer card cage
View of the burnt components on the DMB 6400 controller card. Click image for view of entire card cage.


This system burned out some caps near the voltage regulators of a card labeled DMB 6400. Otherwise the system seems ok enough to attempt a restore. I have zero info on this machine, but it seems similar to other S-100s of this era. More to come.

More photos

Systems Group Ads from Byte (System 2800, Dec 1981, July 1982)

Reply
  repairs complete / Need Password by Bill Degnan - 09/02/2017 22:10
Systems Group 2900 S-100 System Measurement Systems and Control Inc I/O card repair
This photo shows the same "DMB 6400" card from above with repairs completed. Printed on this card is the label Measurement Systems and Control Inc. The new caps are orange not blue and as you can see I figured I might as well do all the 4.7uF 35V caps while I had the thing out. I also replaced the 7805 voltage regulator, which I believe was the cause of the blown cap(s) in the first place. NOTE: Photo was taken without flash and is appears yellower than actual. Click image for large view.


The system boots and displays the message above. Of course now I have a new problem, what's the password? Click image for large view.


I found a place where I can download a binary of the MP/M OS disk for a Systems Group 2800, should work for this machine as well.

http://www.cpm.z80.de/binary.html

Right now the computer boots directly into the hard drive, the disk drive is completely bypassed. I assume there is a switch setting somewhere that I can change to cause the system to attempt to boot from the disk drive first. If I can get a disk with MP/M to boot from the diskette drive I can potentially find a backdoor to the password file used by the "Temple University Career Development Computer System" . If that fails, I can attempt to get the password from RAM by using an in-circuit emulator installed into the Z80 CPU slot. By observation I believe the password test program puts the password in RAM after the first attempt. It does not appear to check the hard drive for the password when you try a new password after the first attempt fails.

Lastly, I cleaned the internal dust and a little gunk from the front grill.

Reply

Resources:


Buy a Commodore Computer Poster

Popular Topics and FAQs


  • Commodore B Series Tips and Tricks
  • Aerocomp TRS 80 M 1 Expansion Unit DDC
  • Items Wanted
  • Lobo Max 80
  • Zenith Z-19-CN
  • Prototype PET 2001 photo
  • Using Toggle Switches to Analyze Memory
  • Commodore Disk Archive Project
  • PET 2001 Prototype at Gametronics 1977
  • Jim Butterfield Photo
  • IMSAI 8080 With Processor Tech. Cutter
  • Secrecy is the keystone of all tyranny
  • Cromemco System Three
  • Northstar Horizon - Boot Problem
  • Computer History and Restoration Links
  • Commodore BX-256-80 - 8088 Co-processor
  • S-100 board testing with Z-80 ICE
  • Donner 3500 - an early portable computer
  • Digital (DEC) PDP 11/05 NC Assembly
  • Univac 1219 rescue
  • IMSAI 1.4 BASIC vs. MITS 8K BASIC
  • Fido BBS listing node list 6-13-1986
  • PDP 8e
  • MITS 88-2 SIO (2SIO) for BASIC
  • Visual Technology Inc Model 1050
  • Amiga 2500 Restoration
  • The Evolution Of IBM Computers
  • Replacement teletype print hammer head
  • Archiving and Copying Software 101
  • Computers Built 1940 - 1950
  • CBM B-520 (a.k.a B256-80 or B500 256)
  • RCA COSMAC Microkit
  • Commodore 64K C-116 Mods
  • MITS 8800b Turnmon 9600 baud
  • Catweasel, 8in and 5 1/4
  • Raspberry Pi as Gateway to Internet
  • Digital PDP11 late 1969 early 1970
  • PDP 11/40 72 inch cabinet model
  • PDP 11/40 Industrial 11 model
  • Digitial MicroVAX 3100 30 System
  • Digital VAX 4000-200
  • Commodore 64 / 1541 DRIVEKNOCK
  • Booting the System Using RL02 drive
  • PACS: Reflections by Kathleen Mauchly
  • Tele-Graphic Computer Systems Inc.
  • Commodore B Series SID Jukebox?
  • Installing Core into PDP 11/40
  • Setting Up OpenVMS 7.1 DNS CLERK
  • Felt-Tarrant Comptometer Model J
  • NextStation Color
  • Digital Rainbow (PC100-B2)
  • 1970 Compusad Compulogical Tutor
  • Archiving Papertapes Using DSI NC 2400
  • 1976 P.C.C. Features the MAI JOLT 6502
  • 1961 Beckman DEXTIR Computer
  • UNIVAC 1 and UNIVAC File Computer 1
  • Past Issues:


    plotter model 20170S pic2

    This image was selected at random from the archive. Click image for more photos and files from this set.