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From: davidsen@crdos1.crd.ge.COM (Wm E Davidsen Jr)
Newsgroups: comp.sys.ibm.pc
Subject: Re: .84 usec Timer resolution on PC
Message-ID: <1757@crdos1.crd.ge.COM>
Date: 22 Nov 89 14:17:31 GMT
References: <25235@sequent.UUCP>
Reply-To: davidsen@crdos1.UUCP (bill davidsen)
Distribution: usa
Organization: GE Corp R&D Center, Schenectady NY
Lines: 24

In article <25235@sequent.UUCP> norsk@sequent.UUCP (Doug Thompson) writes:

| To program Timer 0 to Mode 2 do the following:
| 
| 	mov	al, 34h		; Timer 0 - Mode 2
| 	out	43h, al
| 	xor	al, al		; Get ZERO to give full count of 65536
| 	jmp 	$+2
| 	out	40h, al		; load low order byte
| 	jmp	$+2
| 	out	40h, al		; hi order byte

  Could you explain the "jmp $+2" instructions? I mean, I know what they
do, but not why you're doing it. If this is supposed to be a software
delay (a) comments are nice and (b) sad experience tells me that fast
cpus will need more delay than slow cpus.

  A little clarification, please, as to the intent?  Also the "jmp $+1"
in the second part?
-- 
bill davidsen	(davidsen@crdos1.crd.GE.COM -or- uunet!crdgw1!crdos1!davidsen)
"The world is filled with fools. They blindly follow their so-called
'reason' in the face of the church and common sense. Any fool can see
that the world is flat!" - anon