From: "Ralph Wade Phillips"
Subject: Re: ISA IRQ signal active how long?
Date: Mon, 7 Oct 2002 03:26:48 -0500
Organization: Phillips Enterprises
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"Keith R. Williams" wrote in message
> In article ,
> email@example.com says...
> > Eh. The PC wasn't introduced until 1981. Late 1981, for that
> > matter.
> August is "late" in the year?
Well, it's later than February.
I wasn't sure of the exact date - but that it was after August 1,
1981 (since that was the day that the computer store I worked at opened up).
> > And that was with a (for IBM!) very short lead time - 6 months,
> > IIRC.
Possibly. Again, I blame defective ORAM (Organic RAM) for that.
But it WAS a short lead time, for IBM.
> Eh. The PIC was in use way before the PC, in the same stupid way.
> Eh. I had been working for IBM for, umm, seven years at the time.
> I had some small bit of insider information about the PC some
> time before 8/81. Several friends disappeared to Boca a couple
> of years earlier.
> The mode the ISA used was simply stupid (interrupts aren't the
> only stupid transgression of the ISA bus).
On this, you sing to the choir, my friend. To misquote one of my
favorite books, "Crap! I could swallow a bunch of TTL logic and PUKE a
> When doing my mainframe thing (years before the PC), I
> architected a similar, but simpler bus that was used for power
> controls in mainframes. I had the exact same issues to worry
> about so designed my interrupts to be level sensitive (the
> priority was far more complicated though). I went from there to
> a group doing Intel chipsets.
> I repeat: What a hunk-o-junk! I'll repeat: the ISA designers had
> no understanding of TTL. They were ECL designers, and it shows.
Eh. Now it's easier to curse them when I run into the (still
occasional) IRQ contention.
Had that today - but it was a software based problem. Seems like
Win2K wouldn't admit that a SuperIO could share IRQ 4 between the two serial
ports ... when IRQ3 was used for the ISA modem! Snarl!!!