Date   : Wed, 05 Sep 2007 21:03:58 +0200
From   : dkupers@... (dkupers@...)
Subject: Z80 2nd processor

People,

I just acquired an Acorn Z80 2nd processor for my beeb, including all  
books, floppies and even the keystrip.
As I only got two 3.5" and no 5.25", I downloaded the CPM-discs from  
Jonathan (mdfs.net).

Now, when trying to boot to CPM the computer correcty goes to 80  
column mode, says it is the 'Acorn TUBE Z80 64K 1.20'. It then shows  
'Insert CP/M System disk into drive A', reads something from that  
disk, shows 'Acorn CP/M 2.2 - Bios 1.2' and hangs.

Ok, my config: A normal BBC (rev 7), WD1770, DFS 2.26, GoMMC. I  
soldered a LED on LD1 and LD2 in the Z80 (the latter should light when  
the Z80 goes into HALT mode).

When powering up the Z80, LD1 flickers and stays on (as it it supposed  
to), LD2 is off.
The moment the Z80 hangs, LD2 turns on.

I've tried to boot CP/M with the GoMMC off (thus from the disk), with  
the GoMMC on (the bootdisks on the GoMMC), but neither works.

Then I compared the contents of the 4K ROM of the Z80 with a dump of  
the ROM I found on the internet (don't know where). There were 5 bytes  
different (I don't know which 5 bytes, I don't have the dumps over  
here right now). When burning the downloaded ROM into an EPROM and  
trying to boot from that, the Z80 doesn't even boot.

So...
Can anybody shine some light on the fact that the Z80 goes into HALT-mode?

Thanks in advance,

Dethmer Kupers.