
The history of the IBM PC, part one: The deal of the century - masswerk
https://arstechnica.com/gadgets/2017/06/ibm-pc-history-part-1/
======
fuzzfactor
Part 1a.

By this point Microsoft had also supplied the BASIC for Perkin-Elmer's very
expensive Model 3600 "intelligent terminal".

These were more than just terminals capable of limited client-side processing
for time-sharing systems. As stand alone desktop units they were powerful
enough for scientists to acquire data, store it, process it and/or control
data-intensive instruments which a year earlier had required a large non-
desktop host, often a forklift model.

The 3600 was the first desktop to actually resemble an early IBM PC,
horizontal unit having two prominent 5 1/2" floppies, and with the detachable
keyboard (also introduced softkey F-row) & monitor.

Other than that the box was simply a microprocessor & memory with two RS-232
ports (known as serial COM ports ever since later release on IBM PC's), and an
external instrument connection, not supposed to be expandable or upgradable
internally.

ROM bios booted (without a floppy) to a novel Disk-Based Operating System
known as the Perkin-Elmer Terminal Operating System (PETOS) where a few of the
DOS commands were available from ROM, but the remaining majority of the
commands were expected to be present on a floppy residing at DISK0. DISK1 was
expected to usually be employed for application program & data storage.

These were proprietary Perkin-Elmer programs to interface with their own
scientific instruments but many users wanted to develop their own programs in
BASIC like you could on the competitive Hewlett-Packard equipment using their
built-in HP BASIC.

The team that had designed the 3600 had of course been separated into numerous
more rewarding projects.

Anyway Perkin-Elmer got Microsoft to provide the BASIC for the 3600, and and
as we all gained deeper knowledge of PETOS by operating this equipment, it
really helped later when the IBM PC was launched because its DOS had such an
uncanny similarity.

------
yuhong
"Kildall, meanwhile, often didn't even seem certain he wanted to be running a
business in the first place:"

I should mention Gates wrote the Open Letter to Hobbyists. Of course, this was
before "open source" or "free software" even was a term. At the time, CP/M had
a "BDOS" supplied by DRI with the OEM having to write the "BIOS". There were
firms such like Lifeboat which had writing the BIOS as part of their job.

Thinking about it, I wonder if it would have been feasible for Kildall to work
on CP/M full-time at Intel and release CP/M source to public domain instead.
It would be nice if CP/M was the first thing ported to 8086 back in 1978 for
example.

~~~
dragonbonheur
Kildall consulted for Intel. They weren't interested in CP/M when he showed it
to them.
[https://en.wikipedia.org/wiki/Gary_Kildall#Early_life](https://en.wikipedia.org/wiki/Gary_Kildall#Early_life)

------
davidf18
The IBM PC used the 8088 CPU which offered the same 16-bit execution unit of
the 8086 (and thus superior to the 8-bit Apple II) while using only an 8-bit
bus which was the same size bus as the Apple II. The 8-bit bus of the 8088 was
compatible with the more mature 8085 thus allowing the IBM PC to use more
proven, cheaper parts. The 8088 part itself was cheaper than the 8086.

In my view, this was a brilliant design choice and a pity that Apple didn't do
the same.

The 8088 was designed in the Haifa Israeli Design Center.

------
Nomentatus
There are a very large number of key points in this story which directly
contradict previous published accounts - and no bibliography. Color me
flummoxed.

~~~
crb
These are articles reposted from Jimmy Maher's blog. The original post, with
bibliography, is here: [http://www.filfre.net/2012/05/the-ibm-pc-
part-1/](http://www.filfre.net/2012/05/the-ibm-pc-part-1/)

------
Nomentatus
"It was a self-contained, Turing complete, programmable machine no larger than
a suitcase" \- False

Languages can be Turing complete. ISAs (Instruction Set Architectures) can be
Turing complete. Machines... um, no, not of present design. That infinite tape
provides infinite memory including infinite register space. Hard to duplicate
with a real machine. There's a limit to the largest number you could square on
an IBM PC, so it's not Turing complete - in other words, there are functions
it can't calculate, even given infinite time.

~~~
khedoros1
When people say that a physical machine is Turing-complete, they invariably
mean that it is equivalent to a linear-bounded automaton, precisely because an
infinite tape isn't possible for us to construct.

