Connecting the remaining links

The address lines point to a memory location inside the cartridge ROM (or RAM). 16 bits are available for addressing (giving a total of 65536 memory locations, or 64 kilobytes), so we need 16 address lines. The address lines are driven by the 4040 counter chips.

We also need to connect a few more links for other cartridge signals, such as Read (RD), and Write (WR).

Wire links

Solder in the following wire links:

Cut tracks

Cut tracks at the following holes:

Wire links on track side of board

In order to reduce "clutter" on the board, we can make some of our links on the track side of the Veroboard. This is somewhat more tricky than the usual method, and involves soldering directly to socket or component pins.

Cut the wire to the exact length required and strip only a couple of millimetres or so of insulation from the ends. Mount the wire firmly in place using Blu-Tack, making absolutely sure that the exposed ends are not bridging adjacent pins, then solder them.

Here is an example of such a link:

Wire underneath board

and here are the links you have to make.

Progress so far...

Here's what the SMSReader should look like now:

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