30 Aug
2006
30 Aug
'06
8:41 p.m.
On Wednesday 30 August 2006 06:01 pm, Tony Duell wrote:
I remember one computer place I was somewhat loosely associated with around
the tail end of 1984, or maybe early 1985, and they would get in these
Sanyo 555 (?) machines, because they were cheap. They'd swap out the
single-sided drives that the machine came with for some sort of double-sided
drives, and then leave it sitting there in their showroom running Flight
Simulator, which was the acid test in those days. And the salesman would
never mention that you had to get a version that was specific to that
machine, and that the standard version wouldn't run on it.
There were others, like the Xeros (I don't know what model) that a family
member had, for another example.
Now, the
question is how to define 'Non-PC compatible'. After all,
the PC itself isn't that hard defined. If you look on what machines
I would argue the PC _was_ defined by the IBM Techref.
DOS was running, including highly complex
applications like Word,
Autocad or even Windows, you'll find that the common denominator
often just the use of a x86 CPU is.
There's a lot more to a machine than the CPU.
Go back to the time of the IBM PC. There were several other 8088 boxes
around that were not compatible. Sure they might have run MS-DOS or CP/M
86. But you couldn't take a bootable disk from one machine and boot it on
another. In many cases applications programs from one machine wouldn't
run on another, I seem to rememebr at least 3 levels of compatibiliy
:
OS compatible -- the MS-DOS calls were the same, any program that used
those and those alone would run on both machines
BIOS compatible -- the BIOS calls were the same. You could use those (and
MS-DOS calls) and have no compatibility problems
Hardware compatible. The memory map was much the same, I/O devices had
the same registers at the same port addresses, the video system was the
same, and so on. You could 'hit the bare metal' with no compatability
problems.
It is the last level that we normally consider when we talk about 'PC
compatible' I think,
Yes.
I use "clone" to describe those.
--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, a critter that can
be killed but can't be tamed. --Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin