7 Apr
2000
7 Apr
'00
8:04 p.m.
the same, with
a few notable exceptions where the concept don't match
(MS-DOS for example does not have an IOBYTE).
What of those things internal would you have had them leave out in order to
be more different from CP/M, which was a VERY popular OS at the time,
without removing its functionality. Since the features to which you refer
are internal, I assume you have precice citations of common source code,
right? They're certainly not obvious to me in my role as a fairly frequent
user. Since there is only one segment in CP/M, I guess
you've got 'em there. Of
course it really doesn't matter what the location is, does it? I guess any
OS that load a register and then calls a specific location is a copy of
CP/M, right?
Not really, CPM loaded to a specific segment but apps could use any and all
to the then 8086 1mb limit.
You can also
terminate a program by calling location 0000h (again, in a
COM program). In CP/M this causes a warm reset (similar functionality).
It's like saying a FORD is a copy of a Dusenberg because they both use
wheels. The mapping of one register set into the other is not
an accident. Ask
Intel about that! I'm told that CP/M-86 is considerably more than a
translation of CP/M-80. Now you suggest that the roots of MS-DOS are
entirely in CP/M? They may have common roots, as they reflect the then
CPM-86 was not entirely 8080 code lofted, that would never ru without help.
Also there was a loader change implemented, boot loads a file system aware
loader that finds cpm.sys. This was not the 8080 way.
As far as register usage, that is an artifact of PLM used to write the
V1.3/1.4
and later versions of CPM80. With that convention established it was kept
to keep applications that called the BDOS compatable.
I've heard that, too. Does that mean that anyone
who writes a program to
do
what he's seen another program do is making a copy?
You're not even sure
he
actually saw and read the source code. How many
programmers do you know
who'd simply copy someone else's work in a case like this? Everybody wants
to leave his own mark.
DOS 1.0 had COPYRIGHT Digital Research INC inside! There was a quiet
copyright battle that forced DOS 2.0 (buggiest thing in the world!). This
is not
fiction and it was documented.
Buying something that shortens your burden is kind-of
like buying an
integrated circuit rather than making the thing yourself starting with a
wheelbarrow of sand. The fact that Microsoft knew that IBM had gone to
Kildall probably told them what they wanted was sort-f like CP/M.
They didn't care only that there would be apps for it to run like Visicalc!
Allison