Date   : Mon, 08 Nov 2010 03:17:14 +0000
From   : mike@... (Mike Tomlinson)
Subject: BBC B micro repairs

In article <4CD75794.3060903@...>, Rick Murray <rick@...>
writes

Agreed with all Rick has said, plus:

>On 07/11/2010 22:32, Alan Griffin wrote:
>
>> When I turn it on I get the inital short bleep, but not the second
>> one, and no "Basic" appeared on the screen. But there is a flashing
>> cursor at the top left, but the keyboard doesn't do anything.

Is it a small or large cursor?  If the system cannot detect the keyboard
it reverts to a Mode 0 (small) cursor.

> Isn't Break handled specially, or was that RISC OS?

Break is wired directly to the reset line on the BBC B and Master.

>There is a 6522 just below the 6502 (just left of the ROMs) and there is 
>another 6522 to the left of the 6502 next to the floppy controller.
>Try swapping them over.

I'd take both out and see if the behaviour changes.  If it does, put the
user 6522 in the system 6522 position and try again.

The machine will mostly boot with both VIAs absent (but you'll only get
a cursor.)

>You seem to have been lucky - but for others, it is best to diagnose and 
>attempt to narrow the problem down before trying drastic actions such as 
>this.

Very much agreed.

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