BeebMaster - BBC Model B Disc Upgrade

Fitting a
disc upgrade

Here we can see the positions of the ICs which must be inserted into the sockets already on the motherboard. Remember to insert the chips the correct way round, with the "notch" facing towards the back of the computer.

From top to bottom in the picture above, the ICs to insert are:

Top row: IC87 - 74LS123. This will already be present if you have Econet installed in your Beeb.

Second row: IC78 - 8271. Be very careful with this beast, it is rare and it is old!

Third row: IC79 - 7438, IC80 - 7438, IC81 - 74LS393, IC82 - 74LS10

Fourth row: IC83 - CD4013B, IC84 - CB4013B, IC85 - CD4020B, IC86 - 74LS393

The DFS ROM goes in one of the spare sideways ROM sockets in the bottom right hand corner of the motherboard.