A Serial Interface Project for the ZX81 & TS1000

This is the second article of a series dealing with a serial interface with which to connect your ZX81/TS1000 to a printer, modem or other device. Part one dealt with the actual wiring of the circuit; this one will cover the programming required to obtain useful work from the device. (For those who missed Part 1, the wiring diagram for the interface board is shown as Figure 1).