Date   : Fri, 20 Mar 1998 21:59:26 +0000
From   : Stuart William McConnachie <stuart@...>
Subject: Re: Wierd Hardware Problem!

In message <jMPdv4A3$oE1EwoJ@...>, Mike Tomlinson
<jasper@...> writes
>In article <Pine.SUN.3.91.980320095406.12336B-100000@...>, Chris
>Johns <cmjohnj@...> writes
>
>>From what I understand, and this may well be wront, the "burrrrrrrrr" bit is 
>>the sound chip before its gets initialised, I think the "beep" is when the OS
>>initialises the sound system, and does a VDU7.
>
>I think the "burrrrrrrrr" is the result of garbage on the slow data bus
>before the OS initialises the system 6522.
But haven't we established that, as the keyboard is okay, the next
logical step is that the slow data bus is *NOT* working?

I think that the "burrrr" is caused by the sound chip before it receives
the "reset" signal which is generated by a "power-up detect" circuit.
Can someone confirm that the beeb had one of these that ensures a clean
boot up when power is applied?  And that it is connected to the 76489
sound chip??  I lost my Beeb circuit diagram out of my AUG years ago
(regretably).

>The burrrrrrrrr-beeep of the BBC's power up sequence was IMHO one of its
>most endearing features.
I concur!  Must get round to making pcBBC do that too....

-- 
Stuart McConnachie (stuart@...              )
43 The Hollows, Long Eaton, Nottingham, NG10 2ES, UK
Mobile: 0966 224307