Tom Szolyga’s SBC CP/M install through SCM?

[Massimo]

Hello, I've built Tom Szolyga’s SBC and I was wondering if installing and booting CP/M is supposed to be possible using the SCM procedure instead of Grant Searle's original files.

I did use Grant's procedure and it's mostly successful, the step where you load DOWNLOAD2.HEX and issue the GFFE8 command to "reboot" the board into CP/M and save DOWNLOAD.COM on the CF card is a hit or miss.

It did eventually go through and I was able to load more programs into the CF card.

However I was curious to see if following the procedure through SCM had similar issues or if might be smoother, unfortunately in this case the step where you boot into CP/M for the first time (before loading DOWNLOAD) doesn't work at all and SCM hangs there for a while and then goes back to the monitor prompt.

It's not clear to me if CP/M installation via SCM is supported in this board and if it's supported is it CPM-B or another version?

In regard to my issue with Grant's procedure I did test the card and memory with the dedicated SCM apps and found no issues. I'm almost sure it was just a matter of picking the right delay but I still wanted to try the SCM procedure

[Steve Cousins]

CPM-B won't work with Tom's SBC as CPM-B expects:
1/ The SIO to be at address 0x80, while Tom's SBC has the SIO at address 0x00
2/ The register order of the SIO is different on Tom's SBC (see connections to SIO pin 33 and 34)
3/ The clock speed of the SBC is half the assumed so the baud rate will be 57600 instead of 115200

It would be possible to produce a custom version of CP/M using the tools included with the SCM v1.3 source download.

 
File: Configure.asm 
in folder: \SCWorkshop\SCMonitor\Apps\CPM_CBIOS_and_PutSysPlus 

can essentially be modified to define  CDBase as 0x00 instead of 0x80

and define  CDMode as "SC" instead of "RC"

The tidiest way to do this would be to add a new target:
#IF         SSType = "CPM-Tom"
#DEFINE     MPType Z80
#DEFINE     MPBase n/a
#DEFINE     SDType CF
#DEFINE     SDBase 0x10
#DEFINE     SDSize 128MB
#DEFINE     CDType SIO
#DEFINE     CDBase 0x00
#DEFINE     CDMode SC
#ENDIF

I think this should work and give you my latest CP/M build configured for Tom's SBC with the lower baud rate. You need to dig a bit deeper to sort the baud rate.

Stress "I think this should work"

Steve

[Massimo]

I see thanks, I might take a look but I don' t think it's necessary anymore.

I first tried using Grant's files through SCM but when booting CP/M it just hangs for a while and then returns to SCM prompt.

However installing CP/M through Grant's procedure and then switching to SCM to install the SCM version of DOWNLOAD worked fine and I can now just keep using SCM.

It seems the snag I was having it's specific to Grant's automatic reboot into CP/M which doesn't happen with SCM

[Massimo]

I just tried re-assembling the CBIOS and PutSysPlus with the configuration you suggested and it seems to be working just fine at 115200 bps, I didn't have to change the serial port parameters after installing it.

I then used the SCM_Install_Download_code8000.hex while SCM_CF_Format_code8000.hex was used to initially format the CF card, in other words not the ones that start with CPM.

By the way you weren't kidding about SCWorkshop being quirky... it needs a printer installed to start?

Anyway for anyone else reading you also need to add a section like this in the Configure.asm:

#IF         SSType = "CPM-T"
kSSType:    .EQU 9
kBIOS       .EQU 'T'
#ENDIF