Date   : Wed, 04 Jul 2007 13:27:50 +0100
From   : faz@... (neil f)
Subject: Anyone recognise this board?

 

> -----Original Message-----
> From: bbc-micro-bounces+faz=nildram.co.uk@... 
> [mailto:bbc-micro-bounces+faz=nildram.co.uk@...
] On Behalf Of Richard Gellman
> Sent: Wednesday, July 04, 2007 12:44 PM
> To: bbc-micro@...
> Subject: Re: [BBC-Micro] Anyone recognise this board?
> 
> > http://www.anf.nildram.co.uk/board.html
> 
> I'd be hazzarding a guess here, but it looks like a ROM board 
> with a curiously complex address decode logic.
> 
> I would suggest the "two closely spaced IDCs" were actually 
> an IC header, and the ribbon plugged into a ROM socket.
> 
> The large chip at the top right appears to be a ROM of some 
> sort, the rest is all 74-series logic. The 74244s and 74245s 
> are bus buffers, which is curious for anything plugging into 
> a ROM socket, and the presence of the
> 74138 3-to-8 decoder and the 74163 flip-flop are puzzling too.
> 
> The ROM in question is a 16K variety, which eliminates any 
> sort of "uber-ROM" board.
> 
> I can tell you it was made around 1984-85, and whatever the 
> ROM it is, it would appear that Acorn didn't get through many 
> of them as it is from 1982.
> 
> If you're careful with checking the pinout, you should be 
> able to read the 16K ROM in a BBC Micro (there may be a 
> subtle variation in the chip select pins).
> 
> -- Richard


Thanks Richard. I've added a pic of the IDC lead. You'll see
that there are definitely witness marks for two separate IDC
headers - so probably not for a ROM socket. And at over 26"
long, the lead looks like it was intended to leave the case. The
onboard chip is Basic according to Paras (see separate post.

-Neil.