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title: "ZX81 RTTY Receive Program"
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published_at: "2026-01-12T20:22:58+00:00"
modified_at: "2026-01-12T20:22:59+00:00"
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excerpt: "Here's a neat RTTY program receives that RTTY for you. The author interfaced his ZX-81 directly to his home made TU. (I'm assuming TTL signals). He connected his TU to pin 20 of IC1 in the ZX81. It is for a 16K machine. This short RTTY receive program overcomes some of the like timing problems…"
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---

# ZX81 RTTY Receive Program

Here’s a neat RTTY program receives that RTTY for you. The author interfaced his ZX-81 directly to his home made TU. (I’m assuming TTL signals). He connected his TU to pin 20 of IC1 in the ZX81. It is for a 16K machine.

This short RTTY receive program overcomes some of the like timing problems shortcomings and limited display found in some other programs. The program is somewhat difficult to load follow directions closely. First, key in only the first 3 REM statements in the program listed at the end of the article. Then, key in the following short program.