From: "Michael A. Terrell"
Subject: Re: ISA IRQ signal active how long?
Date: Mon, 07 Oct 2002 00:37:29 -0400
Organization: Do I have to? Well, Ok. If you insist!
X-Mailer: Mozilla 4.61 [en]C-CCK-MCD (Win95; U)
"Keith R. Williams" wrote:
> In article <3D9FCE3B.60DAB50D@mfi.net>, firstname.lastname@example.org says...
> > Ralph Wade Phillips wrote:
> > >
> > > Howdy!
> > >
> > > "Keith R. Williams" wrote in message
> > > news:MPG.email@example.com...
> > > > In article ,
> > > > firstname.lastname@example.org 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
I got the information from a retired IBM engineer. He told me they
were not allowed to have a new case designed, and chose the cabinet form
a low end word processing system, including the original single sided
drives. They wouldn't even let them commit the motherboard to copper,
till they had a working, wire wrapped prototype. That was the reason
for using the existing video board with a printer port, and why the PC,
XT, and AT had the IEC connector to power the monitor. The Floppy
controller board came from the same design. I have seen the machines,
and scrapped two of them. The motherboard in the word processor had
several of the typical aluminum IBM IC packages. He told me that IBM
had the motherboard made, a slightly larger power supply, and all they
did was stuff the boards in the boxes, and ship them, just like all the
clone companies did. The market research said they would NEVER sell
1000 units. The PC was to be sold to small businesses to get them used
to a computer, so they could be talked into buying a mini computer when
they hit the meager limits of the PC.
Why would one of the designers of the PC lie about the history? I
met him when he wanted his original PC fixed. It was one of the
prototypes, and had an IBM property tag on it. He said it was still in
his office when he retired, and they told him to take it with him, or
throw it away. He needed a floppy controller card, and the owner of a
computer store was yelling at the old man telling him to throw the piece
of shit in the dumpster because no one, anywhere had any parts for his
computer. He was almost in tears from the abuse, so I interrupted them
and asked what he needed. He told me, and they guy started yelling at
him again. I told him I had several good cards, and offered to fix it.
He told me he had it in his car, so I went to get it, and took it home
to fix it. When he came to my home to pick it up we talked for several
hours about the history of the PC and the machines that followed. I
moved a couple years ago, and in the move I lost my paper address book.
If I could find him, i would put you in touch with him so you could tell
him he was wrong.
Michael A. Terrell