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I'm trying to rescue an old DOS 6.2 application that originally ran on a 486 DX2 computer. I've moved the hard drive into a relatively newer Celeron 633, and everything seems to work fine except for when I try to print to the parallel port (LPT1) using any of the standard printing commands. The signal is sent to the printer, but the wrong characters come out on paper. Specifically:

0123456789 prints correctly.
áéíóú prints correctly.
abcd prints ☺☻♥♦
ABCD prints !"#$ (is 0x2 off)

The loaded console codepage is 850. The printer in question is an HP DeskJet 940C. Unfortunately I don't have a second parallel-port printer to test with.

Why would this change from one computer to the other when the OS is strictly the same, and how do I configure DOS to print correctly?

Thank you in advance.

Alex J
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    If you print a test from the command line (e.g. "ver > lpt1"), does it print incorrectly? I didn't know an inkjet could survive for so long. :) – Jason Nov 08 '13 at 17:28
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    You brave soul... –  Nov 08 '13 at 17:34
  • Jason: Unfortunately yes, it prints incorrectly. I've tried piping to LPT1, the print command, and the application. – Alex J Nov 08 '13 at 18:01

1 Answers1

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Try different settings for the parallel port in the BIOS of the new machine. Compare them to what the 486 supported (it might not tell you; you might need to find docs on the motherboard.)

mfinni
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  • CMOS allows me a choice between Normal, EPP, ECP and ECP+EPP. ECP also lets me pick DMA 1 or 3. I've tried all of them, with different IRQ combinations, with always the same results. – Alex J Nov 08 '13 at 16:26
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    Weird. The mapping of the characters is not consistent with a loose contact on the printer-port or in the cable. In that case the áé etc would be wrong too. By the way: Bios setting "Normal" would be best. The others are not really suited for Pentium and later hardware. (They were designed for VERY slow CPU systems. A 386 was already fast for them...) – Tonny Nov 08 '13 at 17:08