From: Keith R. Williams
Subject: Re: ISA IRQ signal active how long?
Date: Sun, 6 Oct 2002 22:33:54 -0400
X-Newsreader: MicroPlanet Gravity v2.60
In article ,
> "Michael A. Terrell" wrote in message
> > Ralph Wade Phillips wrote:
> > > "Keith R. Williams" wrote in message
> > > news:MPG.email@example.com...
> > > > 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.
> > Remember the little metal door with a screw in the back that covered
> > nothing? There was a battery there in the word processor. 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.
> The DisplayWriter was 8086 based, wasn't it? And the slot design
> was different, IIRC.
The originals weren't even x86. They may have stolen the
infrastructure later, but that had nothing to do with the
> The 8085 based unit was lower in the 5100 family - the 5110 or 5120,
Nope! The 5100, 5110, and 5120's were proprietary micros
> But those could have been IBM chips also.
> The PC used a LOT of DisplayWriter designs in it, though.
No way! The PC was a wild (and lame) duck!
> Hmmm ... Might have to go digging back through the old Byte
You believe Byte? Sheesh! A lot of history has been re-written,
Byte was responsible for much of the early re-writes.