VCF West | Aug 01 - 02 2025, | CHM, Mountain View, CA |
VCF Midwest | Sep 13 - 14 2025, | Schaumburg, IL |
VCF Montreal | Jan 24 - 25, 2026, | RMC Saint Jean, Montreal, Canada |
VCF SoCal | Feb 14 - 15, 2026, | Hotel Fera, Orange CA |
VCF Southwest | May 29 - 31, 2026, | Westin Dallas Fort Worth Airport |
VCF Southeast | June, 2026 | Atlanta, GA |
the strange thing is that before I deleted the EPROMs, I had a screen...
yes exactly, the adapter is only connected to the central socket of the three roms, then there are some wires that go to the motherboard. It connected well to the center socket.... Anyway, I guess what's done is done. The ROM chips looked like they were on a daughterboard of some sort? Are you absolutely positive that's seated correctly? (How does it connect to the board underneath? The schematics sheet on Zimmers seems to say the MASK ROM sockets under it are the 24 pin variety, while the EPROMS are of course 28 pins. Does it plug into a single socket for most of the lines and have single pins going to the other chip selects? Maybe it's just loose from messing with it.)
Yes these are 64K eprom, i used a GQ 4x programmerThose are not 128k EPROMs... (https://www.elnec.com/en/device/Hitachi/HN482764/) and what model of programmer did you use to program them?
unfortunately notWhen you say "It connected well to the center socket." how do you actually know? Have you tested it with a multimeter?
no i have always 0V signal and not waveform signal on pin 3.When you turn the machine on (and immediately after a RESET condition) do you observe CPU SYNC pulses and then they stop?
Scope probe on pin 3 DaveBut how are you testing it?
Dave
in this case then I will have to use the logic probe!But, on a power up or reset condition, the signal will be there for only a short period of time. How are you detecting this if it only lasts (say) 1 millisecond?
Dave
unfortunately I don't know how to give you an answer...If you don't see anything when you press reset, is the reset button a hard reset or a soft reset?
Yes! if i probe cpu pin 39 and i press reset i see the signal which goes low and then stay highIf you monitor the reset pin of the CPU, when you press the reset button do you see any actual activity on the reset pin of the CPU or not?
yes i checked sync signal on cpu...I did ask you a while ago to check the power rails and the clock signal, but you did not do what I asked you to do...