Multigame Assembly

If you bought the new multigame as a kit, then this is where you need to start. It details, with pictures, how to turn the pile of components into three assembled PCB’s ready to plug into your galaxian PCB. To complete the assembly, you will need to solder over 380 joints!

Parts List

• 3 * Pin strip round pins 0.1″ x 40 pins
• 1 * Pin strip 0.1″ x 36 pins
• 1 * 8 pin DIL socket
• 3 * 20 pin DIL socket
• 1 * 24 pin DIL socket
• 3 * 28 pin DIL socket
• 1 * 32 pin DIL socket
• 1 * 40 pin DIL socket
• 2 * 74LS573N
• 1 * 6116 CMOS Ram
• 1 * DS1210
• 1 * Battery holder
• 2 * Filter Capacitor
• 1 * 32 pin Program Rom – ‘Multicode’
• 1 * 20 pin Logic chip – ‘Logic’
• 2 * 28 pin Graphics Roms – ‘GFX 1’ and ‘GFX 2’
• 1 * 28 pin Colour Rom – ‘Colour’
• 4 * IDC connector 6 way 
• 3 * PCB
• various wires

If you just purchased the PCBs from me then you will need to program up some chips ready to install. Grab the files you need from here.

GFX1 and GFX2 are 27C512, Code is 27C040, Colour I usually out in a 27E512 (use BIGCOL.BIN – but can be a fast eprom instead – use COL.BIN) and Logic code (GAL-M3.JED) must be programmed into a GAL 16V8.

Pin strips are used throughout to make the necessary connections with the galaxian PCB. You can make up a longer run with more than one set of pins. e.g if you need a 12 pin run, but only have one of 7 and one of 5 left, you can use these. just make sure that the ends are trimmed so that they do not press against each other and put the pins out of alignment and check that the pins are in line before soldering them all.

You will need to break up the round pin strips :-

• 2 * 20 (for CPU board)
• 2 * 8 (for colour board)
• 4 * 12 (for graphics board)

the square pins are for the connectors. You need 8 * 3 for connectors (arranged to give a 2 * 3 connector – older PCBs used 1 * 6 for these) and 1 single pin for C-Rom connection.

Colour Board

We’ll start with the simplest of the boards, the colour prom replacement PCB.

For this you will need the following parts. Three pin strips, two each of 8 pins in length and two of 3 pins, a 28 pin DIL socket, the colour prom PCB (the smallest one) and the colour eprom, I supply 28 pin ones which will be labelled ‘Colour’, but you can use a 24 pin eprom instead.

Firstly, from the bottom of the board (so it is soldered on the printed side) insert the two 8 pin strips to form the pins that will eventually fit into the colour prom socket on the galaxian PCB. I always find it useful to solder just one end pin on each, and then check that the two sets of pins are parallel before soldering the remaining pins.

Next try fitting the socket in place, and see if the tops of the soldered pins are in the way. If they are, then we need to cut out the cross bars from the socket, as with this one. Simply remove them with a pair of side snips. Now solder this into position with the top of the socket on the printed side. be careful to align the notch to match the one printed on the PCB.

Add the remaining 2 * 3 pin strip, but this time to the top of the board, soldering below on the unprinted side as normal. This is where we connect the lead when we install everything on the main board.

Finally install the colour rom. If you have the 28 pin version, simply install in the socket being careful to use the correct orientation (notched end nearest the 6 pin connector). If instead you have a 24 pin version, this must be installed leaving 4 spare holes at the connector end, 2 each side. The other end should be level with the lower end of the socket. (Picture shows 28 pin installed)

Graphics Board

The assembly of this board is very similar to the one you have just done.

For this you will need the following parts. Five pin strips, four each of 12 pins in length and two of 3 pins, two 28 pin DIL sockets, the graphics rom PCB (the middle sized one) and the two graphic eproms (Labelled GFX 1 and 2).

Firstly, from the bottom of the board (so it is soldered on the printed side) insert the four 12 pin strips to form the pins that will eventually fit into the graphics rom sockets on the galaxian PCB. I always find it useful to solder just one end pin on each, and then check that the sets of pins are parallel and in line with each other before soldering the remaining pins. To change alignment simply melt the solder on the single pin, and move the pins to where they should be.

As before, try fitting the sockets into the two locations to see if they are obstructed by the pins. In this case they are not, but if they were, remove the obstructed cross bars using snips.  Solder these in place taking care to match the notch on the socket to the notch on the board. Add the remaining two 3 pin strips as before, soldering below on the unprinted side as normal. This is where we connect the lead when we install everything on the main board.

finally, install the graphics roms. GFX 1 goes into the socket nearest the connector, GFX 2 into the other.

CPU Board

That leaves us with one final board, the CPU daughterboard.

For this you will need the following parts. six pin strips, two each of 20 pins in length, and four of 3 pins, a single pin, a 40 pin socket, a 32 pin socket, a 24 pin socket, a 20 pin socket, an 8 pin socket, two 74ls573’s, one 6116 ram chip, one DS1210, the CPU PCB (the largest one), the program rom (labelled ‘Multicode’), the game logic (labelled ‘Logic’) and a couple of capacitors. If you are using an NVRAM in place of the 6116 them omit the DS1210 and see the info at the bottom of this page.

As always, we start with the pins to connect this to the CPU socket on the galaxian. Take the two 20 pin strips and place them from the bottom into location. They should only fit into two of the 20 pin runs, the other two being for the 40 pin socket. (solder on printed side) To check for alignment, solder a single pin at each end, and then use the 40 pin socket to see if they fit. You don’t need to push the socket on, just sit it loosely on top.

Now we fit the 40 pin socket into the correct place on the top of the board. Again, if the soldered pins obstruct anything, simply remove the cross bars with some snips. In this case, the socket fits flush with no problem. Check that the notch aligns with the one printed on the board. Work across the board by fitting the 20 pin, 32 pin, 24 pin and 8 pin sockets into location (if using battery). The only IC’s that do not use sockets are L1 and L2 (although I usually fit sockets for these as well nowadays)

Now add the two 74ls573’s into the remaining locations, aligning the notches as before and solder these. As mentioned, you might as well socket these two as well.

Add the four 3 pin strips, the capacitors and a single pin (optional, you can just solder the wire direct to the board, rather than to the pin) and fit the battery holder. (if you are using one)

Insert the ‘Logic’ chip into the 20 pin socket, the ‘Multicode’ chip into the 32 pin socket and the 6116 into the 24 pin socket and we are almost ready to start fitting everything to the Galaxian PCB.

n.b. If you do not want to fit the battery holder, and instead use an NVRAM chip, then you need to add two wire links to where the DS1210 is fitted. You need to link pins 1-8 and 5-6. (as per right hand picture)

Finally, you need to make two cables for connecting the boards, and to cut a single wire for connection to the sprite circuit on the main PCB.  

These are now much easier to make than they used to be, you simply need to cut the ribbon cable to the correct length and fit the IDC connectors using a vice.

To sort the correct lengths out, I place the boards into location on the galaxian PCB I am going to use, and then hold the wire in the approximate place to gauge the length. I then cut the wire a couple of centimetres bigger (just in case) and fit the connectors.

Single PCB I make the graphics cable 12″ (30 cm) long, and the colour cable 6″ (15 cm)

Cocktail PCB I make the graphics cable 9″ (23 cm) and the colour cable 15″ (39 cm)

The final cable, as seen in the installation picture above, is just a single length of wire without connectors that solders from the c-rom pin (by the Z80) on the CPU board to pin 1 of the 74157 at 3J. More about this on the installation page.