Date   : Mon, 09 Mar 2009 08:29:58 -0000
From   : dl.harper@... (David Harper)
Subject: Disable tube?

me@... wrote:

> I'm pretty sure they were fresh, but just in case I replaced them with
> three new AAs, reset the CMOS, re *CONFIGUREd everything, and...
>
> It's still the same. :(
>
> Possibly useful factoid:
>
> My second boot-beep has disappeared. Instead of going boo-beep! it
> just goes boo- and then shows the BASIC prompt.

During the Master boot sequence, the Tube is ignored completely unless the 
appropriate "CONFIGURE" bit in the CMOS is set to "TUBE".

It appears to me that your machine must be failing to write to and/or read 
from the CMOS.

Can you read/write CMOS reliably using OSBYTES &A1 and &A2? If not, then it 
looks like the CMOS chip is trashed, or possibly something in the interface 
it is connected to. If these do work, then perhaps you could try using them 
to write to CMOS byte &F which contains the Tube status bits. (I am not sure 
which bits - the others are to do with the printer and serial port, and can 
surely be ignored until the Tube issue is sorted.) See whether this byte 
will hold data correctly on all bits.

BTW, the second beep is emitted after the machine has found it is configured 
to, or detects, no Tube.

David Harper