Date   : Mon, 05 Apr 2010 17:45:06 +0200
From   : rick@... (Rick Murray)
Subject: "open" beeb bits...

On 05/04/2010 17:32, Jules Richardson wrote:

> but I do think that the beeb community *needs* an "open" ULA design
 > within the next few years (I've certainly got more beeb things that
 > use the ULAs than I have functioning ULA chips)

I think perhaps the first starting point should be availability. If the 
CPU fails, replacements are possible, even if it means pulling apart an 
Oric to get the CPU and/or VIA. [hey - a regular feature on my blog is 
reasonable hardware let down by crap firmware; and if you can get over 
the yuckiness of the Oric-1 keyboard, you can't get over how bad the 
BASIC interpreter is, and it's a weird graphics system too...]

Of more concern, as you suggest, are the ULAs and PALs and suchlike that 
are custom to the BBC range. The video chip, the serial chip, the tube 
chip - non-generic hardware. How many of these still exist "as new"? I 
know Watford used to sell all these bits as replacements, but that was 
twenty-odd years ago.


Problem is, exactly what is involved in recreating something like the 
video ULA? Not only that, but recreating it accurately enough that any 
drop-in replacement functions just like the original. Spare a moment for 
how complicated this process is!


Best wishes,

Rick.

-- 
Rick Murray, eeePC901 & ADSL WiFI'd into it, all ETLAs!
BBC B: DNFS, 2 x 5.25" floppies, EPROM prog, Acorn TTX
E01S FileStore, A3000/A5000/RiscPC/various PCs/blahblah...