REPLAY Installation Instructions for BBC Model B Microcomputer

Remove the REPLAY circuitry from its box, and make sure that none of the pins on the ROM have been bent whilst in transit.

3. Remove the keyboard by: pulling off the keyboard connector from the keyboard PCB; and disconnecting the speaker connector from the computer PCB.

4. Insert the REPLAY ROM into one of the ROM sockets on the main computer board. REPLAY will not function on buffered ROM expansion boards - ie. all boards with the exception of the MR series from Peartree. Do not attempt to fit REPLAY to a plug-in cartridge or ZIF-socket arrangement.

5. Next locate S21 - see figure 2. There are 3 'links' located approximately to the left of centre in the computer, which are S20, S21, and S22. S21 actually consists of two links, which are referred to as north or south (ie. S21 north is the furthest from the keyboard. Remove the 'jumper' which connects together the two pins on S21 north, and push on the REPLAY connector in its place. (It will only go on one way round, with the green wire to the east.) Do not worry if your ROMboard uses S21 south, as this will not conflict with REPLAY.

6. Figure 3 shows where to connect the grey wire's hook-on probe. It should connect to pin 8 of IC22, which is slightly south and to the east of S21

7. Then connect the purple wire's hook-on probe to pin 6 of the 6502 CPU (which is in the very centre of the computer). It does not matter if the CPU is on a ROMboard, RAMboard, or whatever.

8. Installation is now complete. Check all the connections thoroughly. Reconnect the speaker and keyboard connectors. Turn on the computer; it should function as it would normally do - if it does not then turn off immediately.

9. Type *HELP. All ROMs will then respond - including the REPLAY ROM. If it does not, then the ROM is not making a good connection with the ROM socket. Try fitting it to a different socket. If it does respond, it means that the ROM has been installed correctly.

10. Press-in and release the REPLAY button. Note that the button should be kept in for at least l/5th of a second to make sure that REPLAY is entered correctly. The two LEDs CAPS LOCK and SHIFT LOCK should then flash alternately - this indicates that the REPLAY hardware has been installed correctly. If the LEDs do not flash (and the ROM responds to *HELP), it means that one or more of the connections is wrong.

11. We recommend fitting the REPLAY switch in the 'RESET' hole at the back of the computer, although this will mean cutting a small hole in the black plastic covering. Alternatively the switch lead is long enough to extend out of the back of the computer through the ventilation slot.