Re: I can boot MSDOS but not CPM3

Rich,

(Assuming you are using a S100 computers z80 monitor)

That error comes up in the boot process if the value 31H is not found at memory address 100H, this value is used to check that valid code has been loaded for CPMLDR. Take a look at the Monitor code excerpt below:-

CP 31H ;EXPECT TO HAVE 31H @80H IE. LD SP,80H

JP Z,STARTCPM ;AS THE FIRST INSTRUCTION. IF OK JP to 100H in RAM

JP ERR_LD1 ;Boot Sector Data incorrect

IDEerr1:

LD HL,IDE_RW_ERROR ;Drive R/W Error

JP ABORT_ERR_MSG

ABORT_ERR_MSG:

CALL PRINT_STRING

JP ZAPPLE ;BACK TO START OF MONITOR.

ERR_NR: LD HL,DRIVE_NR_ERR ;"DRIVE NOT READY

JP ABORT_ERR_MSG

ERR_LD: LD HL,BOOT_LD_ERR ;"ERROR READING BOOT/LOADER SECTORS"

JP ABORT_ERR_MSG

ERR_LD1: LD HL,BOOT_LD1_ERR ;"DATA ERROR IN BOOT SECTOR"

JP ABORT_ERR_MSG

You mention you are using a 32mb CF card (rather small !!) the CP/M 3 image switched the CF card into LBA mode, not sure if a card as small as you mention supports LBA mode, I'd use a 1GB card minimum and try again.

After a failed boot look at your memory at 100H is should be 31 81 02 CD 00 0B 0E 0D CD 8D 02 0E 09 11 25 02

regards

David Fry

On Monday, January 19, 2015 at 6:05:53 PM UTC, AltairManRich wrote:

All —

I gave up on the ZFDC for now since I can’t get it to calibrate properly (I can’t get the separator frequency above 450kHz with a Qume 242 drive connected), so I went back to the IDE board. I first removed the D82C55-5 (NEC version) and replaced with a regular 82C55AC. I made a DOS 4.01 image from the one on the web site and gave it a whirl and it works! Yipee!

However, I can’t get it to boot CPM3. I’m using the “banked-prop” version and the only message I get is “BOOT error.” I’m using a 32mb CF card. Not sure what’s up with that, but any advice would be appreciated.

Rich

--
Rich Cini
Collector of Classic Computers
Build Master and lead engineer, Altair32 Emulator
http://www.classiccmp.org/cini
http://www.classiccmp.org/altair32