Hi Guys,
I have been able to get CP/M 2.2 booting from the SD-Memory
card. Please find the JAIR-Firmware V1.zip file on the wiki
page.
http://n8vem-sbc.pbworks.com/w/browse/#view=ViewFolder¶m=S-100%20ALTAIR-IMSAI%208080%20CPU%20Board
It will boot CP/M 2.2 and give the "a>" prompt. (I thought
it would be a capital A, but it's not.)
It does not change to Drive B (haven't tested C or D with any
serious investigations).
When trying to change to drive B, CP/M attempts to access Track
0xFF Sector 0, which are not valid. Track should be between 0
and 76 (77 tracks in all) and Sector# should be between 1 and
26. I'm not sure how or where it's coded in the drive parameter
table. Perhaps these are the previous values that just haven't
been initialized properly? I will need to go deep into CP/M
territory to resolve this issue, but don't want to keep you
waiting for some sort of firmware.
Further, I have updated the schematic with the latest changes
and updated the Manual with all the ECO changes (see wiki page).
There are 3 ECO's required:
-Jumper for the SD card
-Jumper for the disconnected IC-H7 (8T97) pin 15
-Change RP2 from 4.7K to 47K (to solve issues with 16550 UART
and 82C50 UART).
I must now unplug this project for 5 weeks. I am exhibiting a
COSMAC ELF collection at VCF-MW in Chicago and have only 5 weeks
to finish my preparations for this.
Mr. Jack Rubin, I have your board packed with my RCA STUDIO II,
see you at the show!
Mr. Matthew Turner, Thank you again for the loan of your Super
ELF. I will get to work on it in a priority sequence (it's
about #7 on my list).
Regards,
Josh Bensadon