That’s great news Dave. Interesting you can get to 8MHz. Not sure why mine was unreliable past 6. Besides my main system with 21 slots, I have a shorter one with 10, even that did not work at 8. I have not fooled around much however. When I get time will go back and try things.
Curious, what jumpers have you on P2.
Looking forward to seen CPM-68K!
John Monahan Ph.D
From: n8vem...@googlegroups.com [mailto:n8vem...@googlegroups.com] On Behalf Of yoda
Thought I would give an update - found the problem with memory - it turns out pin 1 of U2 on the board had a cold solder joint - guess it finally gave out. Reflowed the solder - the ground plane is a pretty big heat sink around pin 1 and can easily get a cold solder joint. Any ways after repairing that and playing with jumpers and switch settings I have 1 Meg of memory working with the S100-68K-V3. I also have the oscillator at 16MHz so the CPU is running at 8MHz and is a buss master. I am using the short S100 mother board from the group so it may have better noise immunity than the 22 slot mother board like you are using. I will do some more testing and want to boost the memory to at least 2 Meg for some experiments. I will get started next on the new monitor and getting data to load from the IDE CF card. Looks like I am on my way to getting CP/M 68K ported. I have a little clean up to do in a couple of areas (upgrade to latest compiler code, etc).
Sounds like you are almost there Dave. My first suspicion would be MWRT jumpers on the bus for this or some other card are not correct. Remember at any one time only one CPU card can drive MWRT. If you switch CPU’s make sure two CPU’ are not driving the line. Also check TMA0* and RFU3 on RAM card line up with switch/jumper settings.
For anybody else out there if you have built the card and have checked all obvious things and still cannot get it working using our Z80 and RAM boards I will volunteer to try and debug it for you since I understand this is a fairly difficult card for some people.
John Monahan Ph.D
From: n8ve...@googlegroups.com [mailto:n8ve...@googlegroups.com] On Behalf Of yoda
That is my plan as soon as I figure out why my memory board stopped working - I need to put the logic analyzer on and see what is going on - it was working - probably had one of the jumpers on cpu card that should not have been when I put in SMB and had 2 boards driving the same line and probably have blown a driver some where - should not be difficult to find I hope.
I have your monitor running and plan to do a new one all in C so that the monitor will be fairly portable across machines by just recompiling in the right target mode with gcc. I have done some testing of the C code and I have most of the details worked out so should not be long. This summer has not afforded me much time with travel and other things.
I got mine working back in June Andrew, have “written it up” here:-
The very simple 68K monitor is working fine also. What is needed is somebody to take the 8086 ROM BIOS code that reads MSDOS/CPM86 code on our 8086 boards for our IDE Board or ZFDC board and hammer it into 68K code to boot CPM 86K.
Has anyone gotten their S-100 68K CPU board V3 working?
I’d appreciate a status update. Thanks and have a nice day!