DPS-1 Restoration


When the system was first donated, we were able to get it to boot by reseating the boards. After a while the system decided not to boot any more. We reseated all of the chips. This changed the behavior, but it still would not boot. You can watch the processor copy the boot EPROM into RAM, then run the boot program, select the diskette, read data, and then go off into the weeds. We sprayed contact cleaner on all of the chips and wiggled them in the sockets. This did not improve the behavior.

We moved the DPS-1 and the LOBO Drives 8" Dual Floppy unit to the lab from the warehouse.

The system powers on, and based on the front panel indicators it appears to run OK. We forgot to bring the Zenith H-19 terminal from the warehouse, and didn't have a DB-25 to DB-9 cable adapter in the lab. We put a CP/M boot floppy in drive A, toggled the RESET switch, then the RUN switch. You can see the ADDRESS BUS lights incrementing when it is copying the boot program from EPROM to RAM. The Drive A light goes on, and you can hear the diskette head activate, but nothing else happens. Using Mike's RS232 breakout box we could not see any attempts by the DPS-1 to send data to the serial console port.

We went back to the warehouse to get the Zenith H-19 terminal. At first power on it didn't display a cursor, but after a few minutes the cursor appeared. We fiddled with the different display modes that were described on a sheet taped to the front of the terminal. We were able to get the terminal into graphics mode, but were not able to get it back into character mode. We changed the configuration switch settings to what they should be, because the baud date was incorrect. The original user probably had to change the baud rate every time the terminal was turned on. We reseated all of the chips, but that did not improve it's behavior.

We tried using a laptop for a serial console, but didn't see anything when we tried to boot the system.

We tried several different diskettes, but none would boot.

To Do:

This system has a complicated boot procedure that is controlled by the PROGRAMMED INPUT switches on the front panel. A note on the system said to push the switches with the green dots down to boot from the diskette. Looking at the movie we made the last time it ran, the switch settings were different from the note on the system. Time to read the manuals and determine the correct switch settings.

We were told by some experts that the DIP sockets on the RAM board are problematic. We should inspect, and maybe replace all of them.