29Cxx are flash memory that usually have the same pinout as 27Cxx EPROM. 28Cxx are EEPROM that usually do NOT have the same pinout as 27cxx EPROM.
@jlwiley1236 жыл бұрын
Make sure on the 8085 board that you have a good solid 5 volt supply to it. I had problems with mine when I was using a 5 volt wall wart that worked with another SBC, but not the 8085 board. Heavier duty PS took care of the problem.
@maxscane56456 жыл бұрын
Have you installed jumpers in place of the DS1210? If you do not install the DS1210 then you must install a couple of jumpers to pass power and Chip Select to your RAM. I think it is mentioned on the silkscreen. Cheers!
@0toleranz6 жыл бұрын
Hi, I had similar problems with my Z80 SBC aka Grant Searles 9 chip CP/M design, I used one of the newer rs232 transceivers that only require small ceramic caps, but that didn’t workout - would you believe it, fake chip it was, probably an older design wich required the larger electrolytic caps. I switched back to my cheap usb2ftdi clone and bypassed the max232 and that worked for the time being. When I then tried to connect to my old Dec terminal I used an external rs232 levelshifter that I found years ago on the old computer junk pile of an bankrupt gone company.
@philiphoeffer74426 жыл бұрын
Have you tried using the Rigol to serial decode the TTL level signals on the UART side of the MAX232( or whatever they use CPE202. etc.). Might also be serial handshaking. Might have to tie the handshaking high.
@IMSAIGuy
6 жыл бұрын
yes tried that. the UART pins seem to be tristated. no output at all
@IMSAIGuy
6 жыл бұрын
opps, sorry, the G80 has tristated lines. This one the 8251 part just seems like it never gets addressed and talked to
@WaldoHazeleger6 жыл бұрын
If you put in a ROM with all zeros, you should be able to see the address bus as a counter. Can you try that ?
@IMSAIGuy
6 жыл бұрын
thats a good idea. NOP NOP NOP NOP ......
@WaldoHazeleger
6 жыл бұрын
Another good way to make sure the Z80 is executing is to measure the M1 and MREQ/RD signals. If the M1 is toggeling, the processor is executing instructions. (I can't make up from your latest videos if your CPU is doing this at all. You seem to be focussed at the SIO chip).
Пікірлер: 10
29Cxx are flash memory that usually have the same pinout as 27Cxx EPROM. 28Cxx are EEPROM that usually do NOT have the same pinout as 27cxx EPROM.
Make sure on the 8085 board that you have a good solid 5 volt supply to it. I had problems with mine when I was using a 5 volt wall wart that worked with another SBC, but not the 8085 board. Heavier duty PS took care of the problem.
Have you installed jumpers in place of the DS1210? If you do not install the DS1210 then you must install a couple of jumpers to pass power and Chip Select to your RAM. I think it is mentioned on the silkscreen. Cheers!
Hi, I had similar problems with my Z80 SBC aka Grant Searles 9 chip CP/M design, I used one of the newer rs232 transceivers that only require small ceramic caps, but that didn’t workout - would you believe it, fake chip it was, probably an older design wich required the larger electrolytic caps. I switched back to my cheap usb2ftdi clone and bypassed the max232 and that worked for the time being. When I then tried to connect to my old Dec terminal I used an external rs232 levelshifter that I found years ago on the old computer junk pile of an bankrupt gone company.
Have you tried using the Rigol to serial decode the TTL level signals on the UART side of the MAX232( or whatever they use CPE202. etc.). Might also be serial handshaking. Might have to tie the handshaking high.
@IMSAIGuy
6 жыл бұрын
yes tried that. the UART pins seem to be tristated. no output at all
@IMSAIGuy
6 жыл бұрын
opps, sorry, the G80 has tristated lines. This one the 8251 part just seems like it never gets addressed and talked to
If you put in a ROM with all zeros, you should be able to see the address bus as a counter. Can you try that ?
@IMSAIGuy
6 жыл бұрын
thats a good idea. NOP NOP NOP NOP ......
@WaldoHazeleger
6 жыл бұрын
Another good way to make sure the Z80 is executing is to measure the M1 and MREQ/RD signals. If the M1 is toggeling, the processor is executing instructions. (I can't make up from your latest videos if your CPU is doing this at all. You seem to be focussed at the SIO chip).