Date : Sun, 26 Apr 1998 07:37:00 +0100
From : Chris Richardson <chris@...>
Subject: B+ 64k RAM Fitting Instructions
Here are the fitting instructions for the BBC B+ 64K Ram Expansion. I
have lost the original email requesting help, this is my reason for
sending it to everyone.
BBC B+ 64K Sideways Ram Daughter Board Fitting Instructions
These instructions are intended for use with the Acorn 64K upgrade
board which may be fitted to the BBC microcomputer model B+. This
upgrade should only be carried out by an Acorn authorised dealer
and should not be attempted by rs of the general public.
The upgrade kit should contain:
l. The 64K Sideways RAM Daughter Board
2. Acorn 64K Sideways RAM Support Disc
3. l770 DFS
4. Instructions for use
If any of these items are missing then yo u should contact your
supplier.
To carry out this upgrade it is first necessary to dismantle the
BBC microcomputer and remove the main PCB. Before removing
the lid of any microcomputer ensure that it is not connected to the
mains power supply.
When the PCB has been removed from the machine proceed as follows:
Modifications to the Main PCB.
l. On the solder side of the main PCB locate and cut the track that
connects pin 13 to pin 14 of IC40 . When cutting the track, take
care not to damage the adjacent signal tracks on the PCB.
2. Locate and cut the track connecting to pin 10 of IC52.
Having completed the modifications, the daughter board may be
fitted. The daughter board should be positioned such that the
solder side of the daughter board is to the outside ( adjacent to
the case ) Of the machine . Insert the pins of the daughter board
into posi tion IC96, having previously cleared this position of any
excess solder, and solder the board in place. Great care must be
taken to ensure that the board is vertical. If the daughter board
is permitted to lean towards the side of the case it will prevent
the case lid from being fitted.
Having installed the daughter board, the 10 flying leads must be
connected. With one exception (the black lead) all the leads are
routed around the rear of the daughter board and under the PCB, the
solder connections to be made on the solder side of the main PCB.
The black lead travels over the main component side of the main PCB and
will be connected by means of the shell housing already fitted to
the lead.
The points to which the 10 leads must be connected are detailed in
the table below.
Wiring Configuration Table
Wire Colour Signal Name Wire Length To Point
Brown QA 255mm IC45 pin 14
Red C/D 265mm IC 46 pin 9
Orange 4M 155mm IC 53 pin 6
Yellow ENB 145mm IC 40 pin 13
Green RSL 125mm VIA hole *
Blue 2M 175mm IC 26 pin 6
Violet ENCAS 165mm IC 52 pin 10
Grey PGRAM 155mm IC 40 pin 12
White Al5 170mm IC 40 pin 10
Black 0/1 305mm S13 North pin
*The VIA hole to which the green lead must be connected is located
next to pins 10 and 11 of IC 63.
When all of the connections have been made the PCB should be replaced
inside the case and the machine should be reassembled.
Before replacing the lid replace the original 1770 DFS with the one
supplied
with the upgrade kit. This replacement is essential as it contains the
utilities
for use with the RAM upgrade.
Having completed the upgrade and replaced the lid, the upgraded
machine should be tested.
A test routine is supplied on the disc that accompanies the upgrade.
To run this test, enter CHAIN"TEST" <RETURN> and when the > prompt
reappears, press the BREAK key. Ypon completion of the test a pass
or fail message will be displayed.
--
Chris Richardson 8-Bit Software
The BBC and Master Computer User Group and Public Domain Library
http://www.karoo.net/8bs
mailto:chris@...