I'm attempting to transfer files to an old PCjr via null modem serial cable. I cobbled up a quick BASIC script to read data from a serial port and write it to a file, but I've discovered every file I save has an extra byte, 0x1a, at the end.
It seems to be caused by the
CLOSE statement, as even
CLOSEing a file without writing anything results in a one-byte file.
I don't want a SUB character at the end of my files, especially binary ones! Is there an alternate way of writing files that prevents this behavior?
(Using the excellent "PC-BASIC" in a Lubuntu VM for demonstration, but this seems to be a "thing" in all variants of BASIC)
josh2112@jf334-lubuntu-vm:~$ pcbasic -b PC-BASIC 2.0.0 (C) Copyright 2013--2018 Rob Hagemans. 60300 Bytes free Ok OPEN "O",#1,"TEST.TXT":PRINT#1,"hello world";:CLOSE:SYSTEM josh2112@jf334-lubuntu-vm:~$ xxd TEST.TXT 00000000: 6865 6c6c 6f20 776f 726c 641a hello world.
Maybe this can help:
The post discusses how DOS handles copying data with the EOF indicator and how the flags work. Could you batch the copying the files with the switches indicated?
EDIT by question author: Yes, this is it. The specific command needed is
copy src.bin /a dest.bin /b. This strips off the EOF byte from the end of the file. This is even supported way back in DOS 2.10! Annoying that I have to run this extra step after using my BASIC program to save the file, but it gets the job done.