Date: Mon, 21 Mar 1994 07:34:12 -0600 (CST)
From: "Erik Johnson" <johnson AT cdsmn>
Sender: johnson AT cdsmn
To: djgpp AT sun DOT soe DOT clarkson DOT edu
Subject: Timers (again) and also MIDI

I need a little help getting a high resolution timer working under DJGPP.
I have some real mode source for setting timers (timer 0 and timer 2), and
also have played around with the timer.c source in samples\dpmi.  In the
real mode code, they crank up timer 0 and call the original handler at
the same old 18.whatever frequency.  I would like to do the same under
DJGPP.  By doing an outportb(0x43,0x36) outportb(0x40,low) outportb(0x40,hi),
I have been able to increase the timer's speed, however, the system clock
advances far too much because I am chaining the interrupt.

If I try to use the set_protected_mode_interrupt instead of the
chain_interrupt, my routine gets called only once (I preserve all registers,
and return with an IRET).  Must I somehow signify that I am done and the
interrupt was a success?  The real mode code had to read the value at
address 0x20 and then outport it back again.

Can I set up timer 2?  Does it exist in protected mode?

Has anyone written routines under djgpp for communicating with the MIDI
port on a soundblaster?

Thank you,

Erik Johnson