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Shareware Overload Trio 2
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Shareware Overload Trio Volume 2 (Chestnut CD-ROM).ISO
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mkprt101.zip
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MAKEPORT.DOC
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1994-05-12
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2KB
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43 lines
In 1991, Marshall Dudley (author of the popular program Doorway)
wrote a simple utility to correct a problem that occurs on some
computers equipped with an AMI BIOS.
Normally, the port addresses of your serial ports are stored in
memory beginning at location 0000:0040 as follows:
COM1 03f8h
COM2 03e8h
COM3 02f8h
COM4 02e8h
But sometimes after a warm reboot (Ctrl-Alt-Del), the BIOS fails
to write those values to their proper place in memory. As a
result, any communications program which depends on those port
values will fail to operate correctly until you do a cold boot
(press the Reset or turn the power off).
If you run MAKEPORT in your AUTOEXEC.BAT, it will write any of
the port addresses you need into memory every time you boot up
the computer. MAKEPORT 1 will write the address of COM1 (as will
MAKEPORT with no parameter). MAKEPORT 2 will write the address
of COM2, and so on. (Use only the ones you need. If your
computer has only 2 serial ports or devices, then there's no
point writing an address for COM3 or COM4.)
Added in Version 1.01:
In my experience, Marshall Dudley's original program works well
on almost all computers which suffer the problem of losing their
port-mapping on a warm reboot. But I have encountered one very
flakey no-name machine with a May 1991 AMI BIOS that also manages
to lose the address of the printer port LPT1 after a warm boot!
So I added a new option: Running MAKEPORT P will write the value
0378h, the standard address of printer port LPT1, into its proper
place in memory so that the computer can recognize the existence
of the printer.
Neil Parks
5/12/94