Nama
Veteran Member
I’ll call this 'IMSAI fix pt3'.
Pt1 - Getting a Expandoram card working:
http://www.vintage-computer.com/vcforum/showthread.php?46815-ECONORAM-issues-in-IMSAI-advice-needed
Pt2 - While I was waiting for some ‘line delay’ parts for the Expandoram fix, I’d thought I’d pursue setting up the IMSAI as a PT ‘Subsystem B’ system. Still struggling with this, but will probably change direction and now build one of Don Caprio’s 8 slot motherboards as the ‘Subsystem B’ system:
http://www.vintage-computer.com/vcf...uilding-a-(PT)-SUBSYSTEM-B-without-a-GPM-card
So now that I have the Expandoram card working, I thought I’d try setting the IMSAI up in the configuration it came to me in.
Card 1 - IMSAI 8080 CPU
Card 2 - Expandoram card set to 48k
Card 3 - 8k RAM card
Card 4 - MIO card #2
Card 5 - Versafloppy 1 card
Card 6 - ROM card containing 2708 EPROMs. One at F000h (unmarked), the other marked ‘CBIOS’ at F400h. (I’ve dumped the contents of these already). The unmarked EPROM includes reference to 56k V1.4 CP/M, and the CP/M boot screen content.
Card 7 - MIO card #2
Hooked up to a Dual LOBO 8” drives (SHUGART mechanisms). I been cleaning this over the last few evenings, and powered it up for the first time last night. No explosions.
Both MIO cards have cables running from the MIO SIO connectors to female DB25 connectors on the back of the IMSAI. A single external serial cable (hand made) was also included with male DB25 connectors at either end (also tried another known working serial cable too).
I also received a small handful of 8” floppies, some with CP/M written on them!
Last night I tried powering up the entire unit for the first time. I connected the supplied cable from the MIO #1 card to my Mac running a terminal program.
I set the IMSAI switches to execute at F000h, and after a few test trials with blank 8” floppies incase the drive chewed them up, I inserted one floppy labelled CP/M.
On executing the code, the drive dropped the head, and went though a series of head moves, and the front panel flashed with activity. After about 10 seconds the head lifted and all activity stopped…I could almost imagine it actually loading CP/M, unfortunately there was no activity over the serial connection. I repeated the procedure connecting to MIO #2. Still no go. Nothing seems to be sent via the serial MIO cards.
I could be wrong, but I would have expected with this setup to see the CP/M message pop up in my terminal with one of the MIO cards connected. Please correct me if my assumption is incorrect.
These MIO cards have a lot of jumpers and I started to map out how each card has been setup, to better understand the issue, not that I completely understand much of it yet. Complex boards:
__________
MIO #1
9600 baud
Bit rate not set for Cassette
UART Config:
Do not transmit or check parity
Transmit 1.5 stop bits for 5 bit characters, 2 for all others
8 Bits/Character
Generate and check Even Parity
SIO UART TD line to EIA transmitter #1
Receive ready to bit 3
Transmit ready to bit 4
__________
MIO #2
1200 baud
800 bit-rate for Cassette
UART Config:
Do not transmit or check parity
Transmit 1.5 stop bits for 5 bit characters, 2 for all others
8 Bits/Character
Generate and check Even Parity
SIO UART TD line to EIA transmitter #1
Receive ready to bit 3
Transmit ready to bit 4
__________
One thing I have noticed on the MIO #1 card, is that there is no jumper on the ‘External Address jumper’ section. From a quick look at the manual, I believe it needs something here, otherwise no I/O port group is selected. Maybe the jumper has fallen off?
MIO #2 has pins 3 and 14 jumpered to activate Address bit 2.
Finally the MIO manual seems to have a few tests programs that I’ll start to work through, but any thoughts or insights would be most welcome.
My biggest question is in what situations would you use two serial lines? Unfortunately I have no idea what the IMSAI was hooked up to previously.
Cheers
Phil
Pt1 - Getting a Expandoram card working:
http://www.vintage-computer.com/vcforum/showthread.php?46815-ECONORAM-issues-in-IMSAI-advice-needed
Pt2 - While I was waiting for some ‘line delay’ parts for the Expandoram fix, I’d thought I’d pursue setting up the IMSAI as a PT ‘Subsystem B’ system. Still struggling with this, but will probably change direction and now build one of Don Caprio’s 8 slot motherboards as the ‘Subsystem B’ system:
http://www.vintage-computer.com/vcf...uilding-a-(PT)-SUBSYSTEM-B-without-a-GPM-card
So now that I have the Expandoram card working, I thought I’d try setting the IMSAI up in the configuration it came to me in.
Card 1 - IMSAI 8080 CPU
Card 2 - Expandoram card set to 48k
Card 3 - 8k RAM card
Card 4 - MIO card #2
Card 5 - Versafloppy 1 card
Card 6 - ROM card containing 2708 EPROMs. One at F000h (unmarked), the other marked ‘CBIOS’ at F400h. (I’ve dumped the contents of these already). The unmarked EPROM includes reference to 56k V1.4 CP/M, and the CP/M boot screen content.
Card 7 - MIO card #2
Hooked up to a Dual LOBO 8” drives (SHUGART mechanisms). I been cleaning this over the last few evenings, and powered it up for the first time last night. No explosions.
Both MIO cards have cables running from the MIO SIO connectors to female DB25 connectors on the back of the IMSAI. A single external serial cable (hand made) was also included with male DB25 connectors at either end (also tried another known working serial cable too).
I also received a small handful of 8” floppies, some with CP/M written on them!
Last night I tried powering up the entire unit for the first time. I connected the supplied cable from the MIO #1 card to my Mac running a terminal program.
I set the IMSAI switches to execute at F000h, and after a few test trials with blank 8” floppies incase the drive chewed them up, I inserted one floppy labelled CP/M.
On executing the code, the drive dropped the head, and went though a series of head moves, and the front panel flashed with activity. After about 10 seconds the head lifted and all activity stopped…I could almost imagine it actually loading CP/M, unfortunately there was no activity over the serial connection. I repeated the procedure connecting to MIO #2. Still no go. Nothing seems to be sent via the serial MIO cards.
I could be wrong, but I would have expected with this setup to see the CP/M message pop up in my terminal with one of the MIO cards connected. Please correct me if my assumption is incorrect.
These MIO cards have a lot of jumpers and I started to map out how each card has been setup, to better understand the issue, not that I completely understand much of it yet. Complex boards:
__________
MIO #1
9600 baud
Bit rate not set for Cassette
UART Config:
Do not transmit or check parity
Transmit 1.5 stop bits for 5 bit characters, 2 for all others
8 Bits/Character
Generate and check Even Parity
SIO UART TD line to EIA transmitter #1
Receive ready to bit 3
Transmit ready to bit 4
__________
MIO #2
1200 baud
800 bit-rate for Cassette
UART Config:
Do not transmit or check parity
Transmit 1.5 stop bits for 5 bit characters, 2 for all others
8 Bits/Character
Generate and check Even Parity
SIO UART TD line to EIA transmitter #1
Receive ready to bit 3
Transmit ready to bit 4
__________
One thing I have noticed on the MIO #1 card, is that there is no jumper on the ‘External Address jumper’ section. From a quick look at the manual, I believe it needs something here, otherwise no I/O port group is selected. Maybe the jumper has fallen off?
MIO #2 has pins 3 and 14 jumpered to activate Address bit 2.
Finally the MIO manual seems to have a few tests programs that I’ll start to work through, but any thoughts or insights would be most welcome.
My biggest question is in what situations would you use two serial lines? Unfortunately I have no idea what the IMSAI was hooked up to previously.
Cheers
Phil
Last edited:
