Date   : Tue, 16 Oct 2007 00:24:12 +0100
From   : public@... (Daniel Beardsmore)
Subject: Video ULA compatibility query

Pete Turnbull wrote:
> On 15/10/2007 23:22, Daniel Beardsmore wrote:
>> I imagine most Beeb fans will be aware that the original Ferranti video ULAs
>> on the Issue 4 and earlier would cook themselves and end up displaying all
>> sorts of weird visual defects like snow, stripy colours, bad default palette
>> entries (entry 3 in mode 2 showing red instead of yellow) and just general
>> garbage on the screen.
> 
> Yes, they're supposed to have a heat sink -- and with that, they're OK 
> (until the white gooey heat sink compound dries out or oozes away, and 
> needs replaced).

Nah, all mine had the heatink plus the compound, still sticky. As far as I
can tell, the chip just burns out anyway. Pretty sad really -- I've only
ever had two Issue 4s still with a working ULA :P Ever.

> It was supposed to be a drop-in replacement, but the early ones (VC2023) 
> had a problem in that they didn't correctly switch settings between 
> teletext and non-teletext modes.

Ah, good point. I may have been using an older IC with that computer. Thanks.

I finally got that computer back, and put my only working Ferranti ULA into
it and sold it back off to someone up north.

That computer without the good ULA then got the VC 2069 out of my beloved
Issue 7 (first one I ever got hold of) that I broke (trying to put a ROM
into a Sidewise board; cracked a wire on the motherboard somewhere ...
D'OH!) but that worked fine. Now I know why :)

I have one other Issue 7, a rare one with a newer keyboard model but with
the space bar broken. Either I'd have to repair the space bar or, sadly,
throw out the fancy new keyboard and replace it with a classic keyboard.