Search Posts:



Return to Threads

  S-100 DAJEN SCI by Bill Degnan - 02/13/2010 21:06
This thread will contain a review of selected EPROM cards for S-100 systems.


  DAJEN SCI by Bill Degnan - 08/19/2011 23:41
With help from fellow MARCH member Jon Chapman I was able to get access to the SCI card. I used it in my California Computer Systems 2200 with a Vector Graphics ZCB board (that Jon repaired).
Jon also made an ROM add-on that automatically changes the system to 9600 baud, the default is 110.

Summary of DAJEN SCI operations with a ZCB Z80 board (optional)

1. I set up a serial switch box. I plugged each card into the switch box using the ribbon cable

A: The ZCB
B: The SCI (with null modem adapter)

2. I loaded the system and did not disable the ZCB. It booted into the Northstar Monitor 1.5 as always (9600/8/N/1) and gave me the . prompt

3. I ran the command G D000 to jump to the SCI monitor

4. I switched to channel B, hit return, and got to the SCI > prompt. I switched the terminal to 9600/7/N/1.

(Since then I learned I could just boot the ZCB 7/N/1)

5. I was able to run commands using the SCI monitor

1. Try using the prom burner on the SCI
2. Try running the SCI in my Altair 8080 style, which is the original CPU intended by DAJEN for it's SCI board. The little jumper wire at the bottom left needs to be pulled out of the upper plug and put into the lower plug, in order to autojump to the monitor. You can see it just below two 74L IC's on the left of the board. In the upper plug position the autojump is disabled.

  Regulator Issues by Bill Degnan - 01/24/2016 21:06
Today I measured the 4 voltage regulators on the DAJEN board.

My DAJEN is not generating a prompt, lights 15/14 blink furiously upon
RUN, indicating a problem. The ROM loads into memory. I have issues with
the regulators 23 and 3, as described below.

IC-1 LM 340T-5 should be +5V is actually +5.06
IC-2 LM 340T-12 should be +12v is actually +12.21
IC-23 LM 320T-5 should be -5V is actually +12 (input voltage is +17V)
IC-3 LM 320T-12 shold be -12V is actually +5v (input voltage is +17v)

I double checked to confirm the LM320T-5 and LM320T-12 are in the correct
locations and not accidentally reverse installed. I asked Jon if he had seen this kind of reading before to get a second opinion. I assume my DAJEN is not specially wired, and that these two regulators need to be replaced. I am waiting to see what Jon says if I'm correctly interpreting this diagnosis.

I also double checked to be sure that the SCI monitor is being loaded into RAM, and at least the first few dozen instructions are.



Buy a Commodore Computer Poster

Popular Topics and FAQs

Past Issues:

drives misc

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