Solidisk sideway RAM/ROM

The original Solidisk sideway RAM system (introduced Dec. 1983):

Solidisk 16K, 32K and 128K boards:

Solidisk 128 K sideway RAM:

As you can see, part of the corner of the keyboard has to be sawed out to fit this, very uncool.

With a type 2 keyboard it also doesn't fit without sawing (you can see the board cannot be depressed entirely into the soldisk base now, and even if it made contact properly, the BBC's lid would not fit):

Another problem is weight of the 128K board which means one really needs to use strong sticky tape near the TV modulator to securely fix it. There's yet another problem with the Solidisk boards, which is apparently caused by non-buffering of the address bus: On fast reading & writing to swr, errors may occur (I presume the problem only occurs when reading a few bytes then writing a few bytes and so on, not when reading or writing a large block, information is a bit vague on this problem and I haven't used the Solidisk stuff enough to know myself). Also a bit messy is the address decoding, which isn't complete, so writing to bank 1 will actually write to 9, and reading 3 will read 11 etc (0-2 are the remaining on-board ROM sockets). Btw, I've made a program to determine the sideway ram write select type (there are many!) and which banks are RAM; see the BBC software page.

UPDATE: It is possible to fit the 128K board without sawing into the keyboard, but the lid will then only fit with force, which bends the keyboard PCB and the result is that the bottom part of the BBC's case will crack around the screw that fixes the keyboard on that side. I've seen this on 2 machines...

The Solidisk 2Meg 128K board (introduced, ca. May 1987):

This is smaller than the 4MHz boards, so using DDFS interface boards is not a problem. It is installed in the 6502 socket, with 3 leads to switches 20,21,22.

Note that all the ICs have been socketed in turned pin sockets by the previous owner! A write protect switch for the sideway ram can be fitted (as it was originally, but removed from this board) by soldering wires in the 2 holes at the top.

Last modified: Fri Nov 2 01:06:46 CET 2012