The 464plus 128k internal upgrade

Introduction
Firstly, before you even think about opening your Computer, make sure that you have read and fully understand these instructions, I have included some pictures so that you can see what I mean (all diagrams are reproduced with the kind permission of Future Publishing). This upgrade will enable you to run 128k only software and games on a 464plus without the need for an unsightly RAM pack or connecting cables, This is possible because both of the plus machines share the same circuit board. So by putting the extra RAM chips and a couple of resistors, capacitors and some wire we can increase the memory available from 64k to 128k. This is worth it just to play PrehistorikII in the 6128 plus enhanced mode. Look apon being able to use Advanced Art Studio as a bonus!

Time to get your hands dirty!
Ok we now know why this is such an 'easy' task that lies ahead, but how do we actually achieve the goal...

  1. Switch off the power, then disconnect all cables & add-ons. Undo the six screws on the under side of the computer and release the three plastic catches. Open the 464plus (remember to remove the cartridge first).
  2. Remove the keyboard from the circuit board by gently pulling on one of the connecting film edges, and then the other. Remove the two pairs of wires that attach the upper case to the circuit board, now disconnect the tape deck by pulling the connector upwards. finally unscrew the main circuit board from the lower case and place it on a cloth or similar protective surface.
  3. Look at fig.1, then locate the new components to be fitted.

    So now we can see where all these new components are to be fitted, but what are they all, here is a complete list of what you will need.....

    Quantity

    Description

    Part #

    2

    41464 (or equivalent)

    IC12 / IC13

    1

    10k (Brown Black Orange) resistor

    R28

    1

    33R (Orange Orange Black) resistor

    R55

    2

    0.1uF 12v ceramic capacitor

    C12 / C13

    1

    47uF 16v electrolytic capacitor

    C99

    2

    18 pin IC socket

    IC12 / IC13

    1

    length of wire

    wire link
         
  4. Once you have worked out what is going to go where, it is time to remove some of the solder from the hole in the board, This is easiest to do with a solder sucker (available from any good Electronics store) having removed the surplus solder, it is time to solder in the components, start with R28 & R55, bend the legs of the resistors into the holes that you have cleared of solder, and then push almost all the way through it does not matter which way round the legs are fitted, but the resistors MUST go into the correct places on the board, solder on the reverse of the circuit board and snip off any excess wire.
  5. Now you can fix the two ceramic capacitors (C12 & C13), these can be fitted either way round, so just poke a leg through each hole and solder and trim in the same way as the resistors.
  6. Look at Fig2, this is a close up of the positioning of the electrolytic capacitor (C99)

    this can prove difficult to fit, as their are no hole for it to fit into! instead the legs have to be bent as in the diagram above. as this component MUST be fitted the correct way around, the side of the component with the black stripe on it is the negative side, and MUST face to the right when the board is looked at from above. Solder the positive side of the capacitor (C99) to pin 18 of the existing RAM chip (IC11) then solder the negative side of the capacitor (the side with the black stripe) to the leg of the resistor (R88) which is also already present.
  7. Next attach the wire link to pin 1 of the same RAM chip (IC11) and the other end into the hole indicated in fig 2. next to the white printing of a vacant component position.
  8. Finally, solder the IC sockets into the spaces on the circuit board, either side of the existing RAM chip (IC11), These can be tricky to get soldered in so be patient and very careful. Once the sockets are in place, fix the RAM chips into them (making sure that the notches are facing to the back on the board)
  9. Once the chips are in, you can rescrew the board onto the lower casing, reattach the tape deck, keyboard and upper case wires, reassemble the case and screw shut, then it is just a case of reconnecting the wires from your monitor and replacing any add-ons that you have.
  10. Now you can switch on your new 128k 464plus and enjoy all the extra power and speed that it gives to you. and just where did you put that tape of PrehistorikII or Fluff!

 

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