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How-to disable irq4 serial ints

DISCUSSION Stas Sergeev 2 participants 2 messages Jun 10, 2005

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Stas Sergeev

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#0 lore raw

Hello.

Quoted 3 lines · Hufnus

Problem is, if the serial device on /dev/ttyS0 is receiving data and generating ints, this serial servicing tsr crashes during its init.

So finally you did what I suggested, and located the broken DOS program instead of presuming the bugs in dosemu? Good work, keep it that way:)

Quoted 3 lines

Basically I was wondering, if masking the PIC with a 0x04 by doing I/O to port 0x21 would work in dosemu emulation or if there is a better way to do this?

This *of course* works under dosemu. But this may be irrelevant. Because unless I am seriously mistaken, the DOS doesn't unmask the serial port IRQs by default. So if this is the problem, you have to search further and locate another broken program of yours that unmasks the IRQ and forgets to mask it back before exit.

#1 lore raw
Quoted 7 lines · On Fri, 10 Jun 2005 19:38:42 +0400 Stas Sergeev <[email protected]> wrote:
Quoted 3 lines · Hufnus

Problem is, if the serial device on /dev/ttyS0 is receiving data and generating ints, this serial servicing tsr crashes during its init.

So finally you did what I suggested,
and located the broken DOS program
instead of presuming the bugs in dosemu?

I am afraid that is not exactly true! It is related to dosemu not being 100% DOS compatible, when handling these programs of ours. Because they have been un-crashable for the 20 years that they have been shipped to customers on vanilla Dos 3.2 - 6.2

I dont see a fault with Dosemu handling of serial, execept when we mix it with this Quick Basic/asm Serial I/O TSR combination!

It only crashes Dosemu on a Dosemu restart, if the serial device is left ON, sending I/O at 1200 baud.

It does not crash when Dosemu starts or when the asm Serial I/O TSR installs. It crashes on the initial requests between the Quick Basic Gui trying to start getting serial data events.

Its a hard debug, but we are slowly narrowing THE WHAT is happening, so it can be resolved, whatever it is...

But it is related to Dosemu 1.2.0 -> 1.3.2, with MsDos 5.0 files, with our 2 programs, not getting along when Dosemu starts while serial events are takin place.

The hole issue started when we discovered that: after about 20 or 30 days of continuous running the dosemu clock date/time would get corrupted. So we started restarting Dosemu about once every 10 days to get around the corruption.

It is still NOT clear what is at fault,
but it works with real DOS, but that is a
different environment.

Thanks
TonyB

Quoted 13 lines
Quoted 3 lines

Basically I was wondering, if masking the PIC with a 0x04 by doing I/O to port 0x21 would work in dosemu emulation or if there is a better way to do this?

This *of course* works under dosemu.
But this may be irrelevant. Because
unless I am seriously mistaken, the
DOS doesn't unmask the serial port
IRQs by default. So if this is the
problem, you have to search further
and locate another broken program of
yours that unmasks the IRQ and forgets
to mask it back before exit.

Quoted 5 lines

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