FITTING INSTRUCTIONS FOR THE PEARTREE MR SERIES FOR THE BBC MODEL B
1) Unplug your computer from the mains and all other equipment.
2) Undo the four screws marked "FIX" (two underneath and two at the back).
3) Remove the top cover to reveal the main circuit board and key board.
4) Undo the keyboard mounting screws on either side of the keyboard.
5) Carefully disconnect the ribbon connector from the main circuit board by pulling the connector body, (not the ribbon cable) if it is very stiff, raise either end at a time by gently rocking it end to end, don't rock it side to side.
6) Remove the operating system ROM from it's socket (IC 51).
7) Carefully align the legs of the MR board with the IC 51 socket (you may have to straighten the MR board's legs before hand), and then push the board down into the socket carefully with enough pressure drop into position (another 2 mm's of travel say). The board should now be a snug fit (ie it certainly won't be able to fall out under it's own weight).
![8)]( "Cool")
(Please refer to the diagram) Connect the wire with the larger plastic clip to IC77 pin8, that is press the back of the clip and a little hook will stick out, put this hook under the bottom righthand pin of IC77 and release the clip so that it will spring closed around the IC's leg.
9) (Please refer to diagram) Find S21, pull off the lower plastic link, take the remaining MR wire (with the small link) and fit it to the bottom left pin only, leaving the right hand pin not connected.
10) Replace the operating system ROM in a new socket provided by the MR board (see diagram) with the notch to the top.
11) Fitting is now complete, so..
Cont'd…
For MR3000 owners:-
Fit any new ROMS to the new rom sockets provided: rom priority is from right to left with the MR3000 providing rom positions 12, 13, 14 and 15 while the original BBC Machine's sockets now become 8, 9, 10 and 11. Fit all ROMS WITH THEIR NOTCHES TO THE TOP.
For MR4300 owners:-
Fit any new ROMS to the new sockets provided: rom priority is from right to left with the MR4300 providing ROM positions 9, 11 and 13. The 32k of ram occupies the top two positions 14 and 15. The original BBC Machine's sockets now become 4, 5, 6 and 7.
For MR4800 owners MRA300
The write protect switch can be mounted by fitting in the large hole at the rear (after perforating the plastic label).
Reassemble the computer in reverse order from step 5.
Trying it out.
If you have the MR3000 type
*H.
or
*H..
then press the return to reveal the sideways rom messages.
If you have the MR4800 or MR4300 either do a shift-break or type:-
CH. "loader"
To load in the sideways ram utilities from the utilities disc provided, do a control break (to initialise the rom image, then type:-
*SRAM
and press the return key, choose option 6 to get the built in manual up and scroll through it by pressing the shift key.
Please note that no such disc is provided for the MR3000.
Cont'd…
TROUBLESHOOTING WON'T START
Check that:-
a) The operating system ROM has all its legs in place and none are "bent under".
b) That the operating system ROM has the letters PB04 stamped on
it, if not it has been swapped with another ROM so check the
others until you find it then fit it. c) Is the operating system ROM in upside down? It should have
the notch to the top.
d) Are any of the other ROMs in upside down?
e) Has the keyboard ribbon been refitted one pin out ie., look at either end to see if one (or more) pin(s) are exposed, if so, remove the ribbon and reconnect it so that all the pins and all the holes mate up.
Scans of text pages:
1) Unplug your computer from the mains and all other equipment.
2) Undo the four screws marked "FIX" (two underneath and two at the back).
3) Remove the top cover to reveal the main circuit board and key board.
4) Undo the keyboard mounting screws on either side of the keyboard.
5) Carefully disconnect the ribbon connector from the main circuit board by pulling the connector body, (not the ribbon cable) if it is very stiff, raise either end at a time by gently rocking it end to end, don't rock it side to side.
6) Remove the operating system ROM from it's socket (IC 51).
7) Carefully align the legs of the MR board with the IC 51 socket (you may have to straighten the MR board's legs before hand), and then push the board down into the socket carefully with enough pressure drop into position (another 2 mm's of travel say). The board should now be a snug fit (ie it certainly won't be able to fall out under it's own weight).
(Please refer to the diagram) Connect the wire with the larger plastic clip to IC77 pin8, that is press the back of the clip and a little hook will stick out, put this hook under the bottom righthand pin of IC77 and release the clip so that it will spring closed around the IC's leg.9) (Please refer to diagram) Find S21, pull off the lower plastic link, take the remaining MR wire (with the small link) and fit it to the bottom left pin only, leaving the right hand pin not connected.
10) Replace the operating system ROM in a new socket provided by the MR board (see diagram) with the notch to the top.
11) Fitting is now complete, so..
Cont'd…
Fit any new ROMS to the new rom sockets provided: rom priority is from right to left with the MR3000 providing rom positions 12, 13, 14 and 15 while the original BBC Machine's sockets now become 8, 9, 10 and 11. Fit all ROMS WITH THEIR NOTCHES TO THE TOP.
For MR4300 owners:-
Fit any new ROMS to the new sockets provided: rom priority is from right to left with the MR4300 providing ROM positions 9, 11 and 13. The 32k of ram occupies the top two positions 14 and 15. The original BBC Machine's sockets now become 4, 5, 6 and 7.
For MR4800 owners MRA300
The write protect switch can be mounted by fitting in the large hole at the rear (after perforating the plastic label).
Reassemble the computer in reverse order from step 5.
Trying it out.
If you have the MR3000 type
*H.
or
*H..
then press the return to reveal the sideways rom messages.
If you have the MR4800 or MR4300 either do a shift-break or type:-
CH. "loader"
To load in the sideways ram utilities from the utilities disc provided, do a control break (to initialise the rom image, then type:-
*SRAM
and press the return key, choose option 6 to get the built in manual up and scroll through it by pressing the shift key.
Please note that no such disc is provided for the MR3000.
Cont'd…
TROUBLESHOOTING WON'T START
Check that:-
a) The operating system ROM has all its legs in place and none are "bent under".
b) That the operating system ROM has the letters PB04 stamped on
it, if not it has been swapped with another ROM so check the
others until you find it then fit it. c) Is the operating system ROM in upside down? It should have
the notch to the top.
d) Are any of the other ROMs in upside down?
e) Has the keyboard ribbon been refitted one pin out ie., look at either end to see if one (or more) pin(s) are exposed, if so, remove the ribbon and reconnect it so that all the pins and all the holes mate up.
Scans of text pages:
Statistics: Posted by Zakala — Fri Mar 08, 2024 12:35 pm