Standalone X/Y/ZMODEM for non-PC x86

Richard Cini rich.cini at
Sun Dec 31 10:38:56 CST 2017

All –


                I’m looking for some x86 source code for what I’ll call a standalone version of an X/Y/ZModem (or any combination thereof) for use with a non-IBM/PC x86 machine. Many versions exist on Simtel and other archives but they are executable programs rather than source. 


                The reason for the odd request is that the system that it will be used on is a Seattle Gazelle replica I built based on the one in the VCFE inventory, and the constraints are hardware/OS imposed. None of the I/O ports are at PC-compatible addresses and it has no INT-callable system BIOS. The system does run both MS-DOS 1.25 and 2.0 but the standard character I/O devices other than CON: (LPT and AUX) are mapped to parallel ports on one of the boards. COM1 and COM2 devices don’t exist.


                Ideally it should just take two command line parameters – the file name and whether it’s a transmit/upload or receive/download transaction. I know that the protocol is fairly simple but I was looking to adapt something rather than starting from scratch. I found an implementation of XMODEM in Microsoft BASIC, but it relies on opening the COM1 device to work. I am looking into writing direct hardware access using PEEK/POKE, but I’m not there on it yet.


                If anyone has something usable in their archives, please let me know. Thanks, and Happy New Year to all!






Rich Cini



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