Date   : Mon, 09 May 2005 18:09:07 +0100
From   : Sprow <info@...>
Subject: Re: BBC MASTER - UNUSUAL MOS ROM

In article <427CEA41.30009@...>,
   Mike Howard <aixguru@...> wrote:
> Hi All,

> I have just acquired a BBC Master via ebay.

[snip]

> What is strange is that it is mounted on top of a miniature pcb (of 
> Acorn origin) with a DM74LS04N chip under slung the pcb. The pcb is then 
> mounted on top of a 28 pin IC socket which plugs into IC24 on the 
> motherboard. Anybody any ideas as to what this configuration is for? 

I have a dim and distant recollection that someone ordered the ROM mask but
screwed up the sense of the chip select (which is configurable when you buy
enough). At the time ROM masks were on ridiculous lead times, so it was
probably quicker to get a PCB with an inverter on it made than scrap the
ROMs,
Sprow.