telemonster
Member
Hello all.
Back at it. Trying to get IMSAI 8080 system running both Northstar DOS and CP/M.
My system is:
- IMSAI 8080 with original CPU card.
- 88-2SIO board which features two serial ports (Altair style) and a monitor ROM.
- Just got Godbout RAM 17 w/ 64K, currently top 16K is disabled
- NorthStar Disk Controller, with a VSG in-line
I was using 6 x 8K RAM cards that were problematic. So I just picked up a new to me 64K RAM card which is awesome to replace the 384 RAM chips that made up the 48K before (which was never fully working.)
Last time I messed with it, I was able to use the monitor ROM on the 88-2SIO to write out two copies of Northstar DOS and two copies of CP/M which are already setup for 48K/88-2SIO/Northstar disk controller (yay Deramp!)
The Northstar DOS disk boots... but CP/M just hangs.
I do notice that when I have the RAM17 in, I can no longer front panel examine RAM locations. Also, it seems like the system is always forced to the jumpstart address for the ROM monitor on the 88-2SIO.
I have tried various combinations of dip switch/jumper settings, including enabling and disabling the phantom signal on both the RAM17 and 88-2SIO. I've changed the pair of DIP switches on the RAM17 to turn on front panel memory writes and turn it off. But as far as I can figure, the examine next type stuff is a read operation.
I turned off the jumpstart function on the 88-2SIO thinking that it's just always forcing it's start address somehow and that is blocking the examine next -- but the EPROM becomes inaccessable with that off.
Any thoughts?
Back at it. Trying to get IMSAI 8080 system running both Northstar DOS and CP/M.
My system is:
- IMSAI 8080 with original CPU card.
- 88-2SIO board which features two serial ports (Altair style) and a monitor ROM.
- Just got Godbout RAM 17 w/ 64K, currently top 16K is disabled
- NorthStar Disk Controller, with a VSG in-line
I was using 6 x 8K RAM cards that were problematic. So I just picked up a new to me 64K RAM card which is awesome to replace the 384 RAM chips that made up the 48K before (which was never fully working.)
Last time I messed with it, I was able to use the monitor ROM on the 88-2SIO to write out two copies of Northstar DOS and two copies of CP/M which are already setup for 48K/88-2SIO/Northstar disk controller (yay Deramp!)
The Northstar DOS disk boots... but CP/M just hangs.
I do notice that when I have the RAM17 in, I can no longer front panel examine RAM locations. Also, it seems like the system is always forced to the jumpstart address for the ROM monitor on the 88-2SIO.
I have tried various combinations of dip switch/jumper settings, including enabling and disabling the phantom signal on both the RAM17 and 88-2SIO. I've changed the pair of DIP switches on the RAM17 to turn on front panel memory writes and turn it off. But as far as I can figure, the examine next type stuff is a read operation.
I turned off the jumpstart function on the 88-2SIO thinking that it's just always forcing it's start address somehow and that is blocking the examine next -- but the EPROM becomes inaccessable with that off.
Any thoughts?