Date   : Sat, 21 Apr 2012 21:57:15 +0100 (WET-DST)
From   : BBCMICRO@... (Peter Coghlan)
Subject: Video Problems

>
>Can anyone shed any light on this weird fault.
>On turning on the BBC, it makes the first tone, but not the second. It
>displays a mode 7 cursor where you'd expect it to be (after BBC Computer,
>Acorn DFS, BASIC).
>

The first tone is semi-random noise from the uninitialised sound chip. When
the startup code in the OS initialises the sound chip, it goes quiet. Later
the "BBC Computer" banner, the memory size and a CHR$(7) are printed, resulting
in the second tone.

>
>Typing has no effect. After pressing BREAK (or CTRL-BREAK) however, if you
>type, the cursor will move along, as it usually does.
>It seems to respond to commands, e.g. CLS moves the cursor to the top left.
>The fault is not a teletext fault, as it happens in all modes.
>It's like the computer is working fine, but none of the characters are
>there. Also, typing something like DRAW 1000,1000 doesn't change the screen
>at all.
>

I guess VDU 7 or PRINT CHR$(7) doesn't work either?

Does something like:

MODE7:!&7C01=-1

or

MODE6:!&6200=-1

produce anything on the screen?

Did this machine work for you previously or is a newly aquired unknown quantity?

Regards,
Peter Coghlan.