Date   : Mon, 03 May 2004 22:27:20 +0100
From   : "John Kenyon" <etljwk@...>
Subject: Re: B+ Upgrades

My (tattered) B+ circuit diagram doesn't show any provision for the 
extra 64k however it does show a 32 pin connector with the legend
"IC96 TM4164EK8-12 (Option to replace 8 off 4164-12)"
It looks to me, that using a couple of 62256 32kX8 SRAMs wouldn't 
be possible using this connector - only DRAM would do.

The pins are marked/connected as follows:
1      OV
2      +5V
3&4        RD0     (i.e. DI and DO tied together on the PCB)
5      nCAS
6      XA7
7      XA5
8      XA4
9&10       RD1
11     nDW 
12     XA1
13     XA3
14     XA6
15&16      RD2
17     XA2
18     XA0
19     nRAS    
20&21      RD3
22     Ov
23&24      RD4
25&26      RD5     
27&28      RD6
29&30      RD7
31     0v
32     Not Connected

Hope this helps.

/John


> -----Original Message-----
> From: Majordomo List Manager [mailto:majordomo@...]On Behalf Of
> Christopher Thornley
> Sent: 02 May 2004 23:02
> To: 'gARetH baBB'; 'bbc'
> Subject: RE: [BBC-Micro] B+ Upgrades
> Importance: High
> 
> 
>  Hi,
> Please could you send me a picture of the track side of the board.
> I has acquired a BBC+ 64k machine and would like to upgrade it to 64k swr
> RAM but these interface or chip are not available any more.
> I would like to build an equivalent unit but I need to you the original
> circuit diagram and which pins on the connector it was connected to.
>