Need Another Serial Port

[everest]

Is it possible to use some spare pins on my ZX24a as an extra serial port to communicate with a second PC? I actually need up to two additional serial ports. Will I need a Max232 or similar IC to make this work?
-Jeff

[G Herzog]

The ZX-24a has one hardware serial port provided by the microcontroller that use transistors to drive TX and RX - that is COM1. Others have to be created in software with the DefineCom and other commands. I believe you can add more than one (COM3, COM4, and so on). I believe the limit is 4 additional software ports.The old BX24 was limited to COM3, but that isn't a ZBasic product. Don''t use the DefineCom3 command as it is a legacy item.

Using the Max232 level shifter is often easier and better than building an interface at 0-5volts with transistors, but both are doable options. What likely will not work is direct TTL signals from the ZX-24a to a PC port, while direct signals from the PC port may actually damage the ZX-24a due to being outside the -0.3v to +5.5v range.

It seems that I cannot locate particular specifications for the ZX-24a as it is no longer in production. This seems a recent web site change (removed). I have 4 of them that I intend to use for quite some time. So it might be wise if ZBasic continues to support a legacy documentation effort rather than remove this information. It certainly would mean less effort of having to respond to people one by one.