What do you mean by "pseudo compatible"?
On Mon, 10 Sep 2012, Chris Tofu wrote:
C: Various machines from the early-mid 80s which ran
MS-DOS (their own
version), but little else in the way of IBM s/w. Ones where the salesmen
lied through their teeth about the machine's compatibility. Although
many did eventually sport oem or aftermarket add ons that greatly
increased their IBM s/w compatibility. Those which come to mind are the
TI Pro, Wang, Rainbow, NEC APC III. The Epson QX-10 (Z80) had the Titan
board, but I'm not sure how compatible the QX-16 was stock.
Such as MS-DOS
on a Victor 9000?
C: I gave 2 examples.
OK, but be aware that many people reserve the word "compatible" for only
those machines that are so close that they will run IBM PC software.
Some people would list your examples as "NON-compatible MS-DOS machines"
And then there are plenty in between, such as the Sanyo, RS model 1000,
Toshiba T300, etc. That can run SOME PC software, but not all.
There used to be "testing" of levels of compatibility, usually based on
stuff that was completely irrelevant, such as would it run "Flight
Simulator" or the "5150 ONLY version of XenoCopy" (PCWorld January 1984?)
C: Ok, I have a bunch of NEC APC I disks. I hope to
read them (hope
springs eternal). I have little more then a little hope that they still
work. I'd like to read them on my Canon AS-100. I have NO docs for the
AS-100, and little more then boiler plate for the APC.
Well, I'd recommend starting by getting code working to read them on an
ordinary PC. THEN, once that is working, try to port that code to the
Canon, etc. For example, how do you read a sector on the Canon?
Does it have an Int13h that is close enough in calling structure?
Does it have a similar INT1Eh if you need to change bytes per sector,
etc., or will you need to talk directly to the chip? WD 179x chips have a
completely different communication than NEC 765 -like chips.
The NEC is not too bad.
One gotcha is that the 3.5" HD format is done at 360 RPM at 500K bits per
second, whereas the stock PC 3.5" drives are 300 RPM. You'll need to do a
little work to find compatible 3.5" drives.
The 8" disks, 5.25' HD, and 3.5" HD all had identical format!
NEC APC, in addition to MS-DOS, ALSO had a CP/M-86, AND a
"Stand-alone-BASIC" (similar to the Coco disk format) Last time that I
heard from Don Maslin was when he and I collaborated with Sellam to read
some NEC APC 8" Stand-alone-BASIC disks. (As far as I know, there is no
official name for that format) Don emailed me hex-dumps of the DIRectory
tracks and I determined which blocks of the disks to read.
?C: I also have an IBM DisplayWriter w/8" drives,
but the prospects that
presents are all scary. I have an Intel MDS drive cabinet, that has a
rather codependent relationship w/the 2 8" drives. I was astounded and
nauseated when I actually bothered to look.
For complete
unknowns, you'll find that the number of variations is
rather large.
C: The number of different formats? So, and although my selection
is
quite small, I guess it isn't trivial for a program to randomly search
for format marks. I would have thought otherwise. But what do I know.
I estimate there to be about 2500 different soft sector disk formats.
What I did in XenoCopy was to have an option of having ity look at the
disk, to rule out all formats with different number of sides, different
number of sectors, bytes per sector, etc.
Howard Fullmer (Morrow designs) attempted [unsuccessfully] to do automatic
format recognition.
But, there is nothing stopping you from doing things such as looking where
you think directory entries MIGHT be, etc.
aftermarket board/5 1/4" drive set that I have
for it uses a WD chip).
WHICH WD chip?
C: I don't remember exactly,
Either the 1770, 1771, or 1772 (I think
there was a 1772, no?).
OK, so NOT one of their NEC compatible chips.
WD did make some that were kinda 765 compatible.
But not all.
C: To God be the glory. But I would have thought
though that the 765
would have been the choice for 5 1/4" drives, and the WD family for
larger ones. But again there's yet another exhibition of how little I
know.
WD was the one used in Kaypro, TRS80, and many others.
Until IBM PC dominated the market, and people flodded to NEC 765 for
compatibility, there hadn't been a clear edge of one V the other.
The WD179x can do a few things easily that can't be done (or barely) on
the NEC765. Many people prefer it over the NEC765
?I just don't understand why I can never get an
answer to my original
question...
"You have to ask the right question"
AND include enough of the details!
--
Grumpy Ol' Fred cisin at
xenosoft.com