From: Keith R. Williams
Subject: Re: ISA IRQ signal active how long?
Date: Sun, 6 Oct 2002 22:33:53 -0400
X-Newsreader: MicroPlanet Gravity v2.60
In article <3D9FCE3B.60DAB50D@mfi.net>, email@example.com says...
> Ralph Wade Phillips wrote:
> > Howdy!
> > "Keith R. Williams" wrote in message
> > news:MPG.firstname.lastname@example.org...
> > > In article ,
> > > email@example.com says...
> > > > Howdy!
> > >
> > > > PC standard is edge-triggered, not level-sensitive, for ISA
> > card,
> > > > IIRC. This (and the active-high) I've ranted about since, oh, about
> > 1981
> > >
> > > I ranted about this before '81. I couldn't believe the PC
> > > designers made such a *stupid* mistake. Indeed this isn't the
> > > only transgression. The designers had no idea how to design with
> > > TTL.
> > Eh. The PC wasn't introduced until 1981. Late 1981, for that
> > matter. And that was with a (for IBM!) very short lead time - 6 months,
> > IIRC.
> > RwP
> Yes, but the ISA buss was a holdover from a word processing system
> based on the 8085 that used the same five slot case as the original PC.
What system would that be? The Data-Toaster, err Master,
certainly had nothing in common with the PC. The Delay-Writer
may have, but only after the PC was already popular.
> Remember the little metal door with a screw in the back that covered
> nothing? There was a battery there in the word processor.
No I don't. Perhaps you'd like to remind us.
> The video
> board and floppy drive controller board was the same in both systems. I
> scrapped several of the word processors, because no one wanted them.
> Now, i wish I still had one to show people where the PC came from.
Perhaps *after* the 5150, but not before. There was nothing in
common with any other product. The PC was done by an Independant
Business Unit, and did whatever to go cheap. ...even stupid