Mail Archives: opendos/2000/12/26/07:00:04
----- Original Message -----
From: "Da Silva, Joe" <Joe DOT DaSilva AT emailmetering DOT com>
To: <opendos AT delorie DOT com>
Sent: Thursday, December 07, 2000 3:52 PM
Subject: RE: IBM PC-1 (was Misc., nee BASIC & EMS, nee Optimizing
CONFIG.SYS...)
> I remember being shocked when IBM brought their brand-new "baby"
> into our university, to show us students what "the future of computing"
> looked like. The reason I was shocked was that it used four banks of
> 4116 DRAM's (for a total motherboard capacity of 64K). Given that the
> rest of the world was adopting the 4164 DRAM (with four times the
> capacity of the 4116), I was very much surprised that a "brand-new"
> design such as this, used the soon-to-be-obsolete part.
Yes that was the PC-1 as most people call it. It had 16/64K capability. Six
months later when they officially released the PC it did use the 4164s. The
first bank, BANK 0 was soldered in. There was a truck that could be used to
expand these to 640K on the motherbaord. It involved cutting a line or two
on the MB and soldering a jumper or two and using 256K chips in BANKs 2 and
3. The one I have used Mostek 4564N -20 chips soldered in. This MB was given
to me sevral yeras ago. I just keep the thing for refernce and maybe someday
I'll restore an old IBM PC. I also got moth of the cards that it needs that
are original IBM.
> So, while it is JUST possible that IBM may have considered the 8080
> chip, I really think this is just an exaggeration. While the 4116 was
> "past it's prime", the 8080(A) was well and truly obsolescent, and
> nobody on the planet, not even at IBM, would have been unaware of
> this. The other possibility is that some people have confused the
> 8080 with the 8085, since the latter is/was the successor to the 8080.
> And, as I stated, IBM did have an 8085 design "lying around" when
> the "powers that be" decided to go ahead with the "PC" ...
I thought that was very wierd too, but when I saw it mentioned more than
once, it may have been true. I would have to look it up and see if it was
the same reference or more than one.
It would have seemed much more logical to have chosen the Z-80 or 8085 chip
if they wanted to start with an 8 bit chip. But after seening it stated
twice or possibly more times, who knows. I'll check those articles sometime
and see what the original references they used were. It will be a few eeeks
before I have the time to do it. If they all refer to the same orinial
article, then it may have been a misprint and it may have been the 8085.
An 8085 cab be upgraded to an 8088 and use the same hardware and chipset as
the 8085, but when you do this, you cannot use an 8087 co-processor. Kaypro
and some other manufactures put both processors in thier systems, the 8085
and 8088.
Pat
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