Re: Gemini 80-Bus System
Thanks for the info, I will take some time to absorb the details and start checking things in more detail. I have the circuit diagram and the manual for the 813 so will start there and report back. I have certainly tried the reset button (many times). Pressing it seems to reset the SVC (it redisplays the SVC ROM Version) and activates the reset on the GM813s Z80, however, it doesn't help the system start.
The slow reset rise time you mentioned probably explains another symptom. When I switch the machine on for the first time after a period of rest, the SVC beeps continuously and the display flickers badly, subsequent power ups during the same session start up with single beep and steady display.
John: I am not sure I fully understand the implication of not having the GM813 at the bottom slot as I thought that all of the slots were all wired together via the backplane? In order to gain access to the board I need it to be in the top slot with the SVC below it, would you expect this to still boot (at least to the Simon ROM)?
|