Date   : Thu, 08 Nov 2007 08:22:33 +0000
From   : pete@... (Pete Turnbull)
Subject: ROM / RAM boards...

On 08/11/2007 02:41, Peter Craven wrote:
> How many ROMs could this hold at a time?? Was there any space available 
> for SRAM?

The ATPL Sidewise board provides 12 ROM slots, which become slots 4-15 
in the BBC scheme.  The original 4 slots on the main board are slots 
0-3.  Each slot is provided with one 28-pin socket to hold either an 8K 
ROM/EPROM or a 16K one (some slots can also hold a 4K device), except 
slot 15, which has two sockets, so you can fit a pair of 8K devices if 
you prefer, rather than a single 16K one.  These two devices have to be 
the upper and lower halves of a single ROM image, though, not two 
different smaller images.  Those sockets can also hold SRAM chips, and 
there's provision to have battery backup for them.  It's also possible 
to write protect or disable that slot, as we've mentioned.

The board also has sockets for the MOS ROM and the uPD7002 ADC chip, 
because it fits into the sockets for those two devices.  That's where it 
gets address, data and control signals and power.  It also has two small 
flying leads fitted with connectors to fit in place of link S21, which 
is where it gets the rest of the ROM bank control signals it needs.

-- 
Pete                                           Peter Turnbull
                                               Network Manager
                                               University of York