Cromemco SCC Eproms

From: Pete Turnbull <pete_at_dunnington.u-net.com>
Date: Thu Jan 22 14:35:31 2004

On Jan 21, 17:40, Joe Abbott wrote:

> Just my luck! Thanks anyway, Pete. Hopefully someone
> out there will be able to help.

I hope so!

> I'd bet yours contains the code to disable the onboard
> roms and jump to the floppy boot rom. My System Zero
> manual mentions this and lists the asm code as well as
> a hardware mod. Might be why there doesn't seem to be
> many of these roms around.

Could be. The first EPROM "lives" at 0000H so mine contains:

0000 3E 00 LD A, 0
0002 D3 23 OUT (23H), A ; dunno what this port does
0004 3E 01 LD A, 1
0006 D3 22 OUT (22H), A ; nor this one
0008 21 16 00 LD HL, 16H ; 22
000B 11 00 24 LD DE, 2400H ; 9216 or start of non-SCC memory
000E 01 07 00 LD BC, 7
0011 ED B0 LDIR ; copy 7 bytes from 0016-001C to
2400
0013 C3 00 24 JP 2400H ; and execute there
0016 3E 80 LD A, 80H ; set top bit
0018 D3 2A OUT (2AH), A ; don't even know this one
001A C3 00 C0 JP 0C000H ; start of RDOS?

-- 
Pete						Peter Turnbull
						Network Manager
						University of York
Received on Thu Jan 22 2004 - 14:35:31 GMT

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