PEARTREE COMTUTERS LTD
      NR4200 RAM BOARD

Fitting Guidelines

Step 1 Unplug your computer from the mains and all other equipment.

Step 2 Undo the four screws marked "FDC" (two underneath and two at the back of the computer).

Step 3 Remove the top cover to reveal the main circuit board and keyboard.

Step 4 Undo the keyboard mounting screws situated on either side of the keyboard (2 or 3               depending on which issue computer you have).

Step 5 Carefully disconnect the keyboard ribbon connector from the main circuit board (by               pulling, the connector body, not the ribbon cable) and do the same for the speaker cable         under the keyboard.

Step 6 Remove the Operating System ROM from IC socket 51. 

Step 7 Carefully align the legs of the MR 4200 with ROM socket IC 51 and push the RAM board down        carefully so as not to bend the legs. You will now notice that the MR 4200 sits snugly on        top of the ROMS in the computer.

Step 8 Connect the cables according to the fitting instruction diagram.

Step 9 Insert the operating. system ROM on the MR 4200 (into the leftmost socket) and now insert        your 6264 8kX8 static RAM chips into the remaining sockets.

Step 10 Reassemble the computer in reverse order from "Step 5"

STARTING

software is supplied on a 5 1/4" disc 
Insert the disc into your disc drive and press (Break shift) this will then boot the disc
The disc is formatted to 40tracks on the top and 80 tracks on the bottom but will boot on either drive.

Using The Software Supplied

Load software to sideways RAM: This Command will enable you to load you own ROM images into sideways RAM.
On selecting. this command you will be prompted with the following:
Load to which socket
You must now input the RAM socket number into which you wish to load your ROM image. You will then be prompted with:
Load which file
You must now input the filename of the ROM image you wish to load.

Read ROM or RAM and save to tape disc: This Command will enable you to copy any ROM or RAM content to disc.
on selecting this command you will be prompted with the following:
which socket number shall I read
You must now input the RAM/ROM socket number you wish to copy. You will then be prompted with:
What file name for saved software
You must now name the file to be stored on disc or tape

Clear Sideways RAM: This command will clear all sideways RAM not write protected. You will be asked to confirm that this is correct.

Test Sideways RAM: This command will test RAM chips on the MR 4200 to see if it is write protected or faulty, this command also clears sideways RAM. You will be asked to confirm that this is correct.

Verify file against ROM/RAM: This command will enable you to check an image of a ROM or RAM with a copy on disc.

Edit ROM/RAM: This command is only included in the ROM/sideways RAM version that will have to be loaded into one of the 8k sideways RAM slots and is used to examine and edit the sideways RAM using the following keys:

cursor keys:- Move the pointer
Copy:- Select HEX or ASCII input
Escape:- Returns you to the main menu

Pressing the shift keys while moving the pointer will speed up the rate of movement

ESCAPE: Use this command to leave the software.

You can also enter commands to the operating, system using the star (*) prefix. This allows you to change the current drive or directory, or catalogue the disc.

 TROUBLESHOOTING

WON'T START
This is because either, 

a) one of the MR 4200 pins has failed to make contact with the BBC.
   REMEDY-remove the MR 4200 check for bent pins straighten and then reinsert; or
b) the Operating System ROM has been fitted in the wrong socket. 
   REMEDY-cheek that the leftmost socket on the MR 4200 contains a ROM with the letters PB04        stamped on it. If not find it and fit it to the left most MR 4200 socket. 

PARTIALLY STARTS This is when the BBC machine produces some sort of message or the cursor only                  appears at the top left of the screen with no message.

a) In the latter case, check that the keyboard ribbon connector has been correctly refitted, or     one of the sideways RAMs is either of the wrong type (wrong speed) or faulty.
   REMEDY-check all ROMs fitted, and any RAM chips fitted to the board.
b) If the machine says "Language?" This implies that there is on language ROM present, the          language ROM is not correctly fitted, or that the plug in links are in the wrong positions.
c) There could be some residual information in the RAM. REMEDY-
   switch off the machine, wait five seconds and switch on again.

Additional Tips

We recommend that you clear all RAM banks before you switch the computer off as the RAM banks have a tendency to retain data for long lengths of time.
To write protect the contents of the MR 4200 move the clip connecting pin 8 of IC77 to the + side of the capacitor (c26) which is situated about 2 1/2" to the right of IC77

[Scanned by G0WST]