31 Aug
2006
31 Aug
'06
4:40 a.m.
Am 30 Aug 2006 23:01 meinte Tony Duell:
> 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.
Now, that would be the 5150. In that context, already the 5170 AT
is no longer compatible. And no Pentium system I can think of ever
will be.
> 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.
Jup, but this more has changed several times. Stuff got added and
removed - or different reimplemented.
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,
Which already was a problem for the AT vs. PC. Not every bootdisk
made for the PC could run on an AT - except when willingly (or by
not needing) left out functions that differed.
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,
Again, then the AT is already not 100% PC compatible. What I want to
point out is that the whole concept of PC-compatible is quite blury
and it comes down to all and every single application (and person using
the programm).
Also, your levels are not realy based on each other - as said before,
we hat Workstations where the hardware was made from standard PC Main-
boards (e.g. Tyan) but the Boot code was different (And no PC-BIOS), so
it could not eat a standard boot block - but they could be loaded from
a SCSI tape :)
To make it fun again, there where boot Disks that loaded a RAM based
BIOS, and then went ahead like any other PC.
> Thus every Pentium based computer would be
PC-Compatible by definition.
By that defitinion _any_ computer is PC-Compatible. My
HP71 could run an
interpreter written in BASIC that treats a couple of 9114 floppies as the
main memory of an emulated PC, and boots MS-DOS from a third one.
Accesss to video RAM could be sent to the HPIL video interface, and so on.
The fact that it would take years to even get to an MS-DOS prompt is
irrelevant :-)
Righto - exactly my argument.
But OK, I'll rephrase the question. Are there
Pentium-based machines that
can't run the standard Windows we all know and hate, or a slightly
modified version of said software (and for reasons other than the trivial
ones of insufficient memory or disk space etc). That is, I am thinking of
machines with very different I/O devices, etc.
The question is, wehn does this start. I mean, You can boot a
Windows XP CD from almost any Pentum (alike) based Machine that
supports BIOS compatibility - all you need is having a disk with
all needed drivers ready. Beside all the Windows-bashing we do
(And I enjoy it too), it is a rather hardware independent OS
Everything is covered in loadable driver layers. In cat, it bears
less of a problems to get Windows running on weired machines than
to get Linux running.
Now, we have her machines with no IDE ports, no Floppy drives,
all Disk-I/O is done via SCSI - still, I can boot and install
a Windows. No doubt, SCSI was not part of the PC definition as
done in the TechRef.
It appears such machines do exist. And I would argue
that once they reach
sufficient age they should be considered as 'classics'.
As I said, there have been several Workstations with PC-Hardware,
but different Boot/BIOS-Code (e.g. Siemens WS 200). We had Pentium
based Unix machines, thet definitly where different from PCs
(Multibus based Boards) but still where using the same cheap
support chips - so port addresses have been mostly the same.
is it now a PC or not ?
Gruss
H.
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VCF Europa 8.0 am 28/29.April 2007 in Muenchen
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