lenny@quincy.UUCP (Lenny Tropiano) (10/05/87)
Here are some of the mailed responses I got in reference to the
DOS-73 Coprocessor. There might be more followups if I get more mail!
I still don't have specifics on getting it for $300! But will keep
you posted :-).
-Lenny
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From: ...ihnp4!ihlpf!spear
It is a quite slow board - definitely won't handle 9600 baud terminal
i/o. Screen update also seems slow and is limited to Hercules
graphics. But it pretty much works if you can tolerate the speed and
don't need CGA.
Steve Spearman
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From: ...mtune!ihwpt!lgm
Lenny,
I saw your question on Usenet concerning the DOS-73
Board for the UNIX PC. I myself have a DOS-73 Board
on my UNIX PC 3B1. On the whole I am very satisfied
with the board and its interface to the UNIX Operating
System side of the machine. With the board I have
access to all the public-domain and commercial software
written for MS-DOS, and I don't have to buy a second
set of peripherals (monitor, modem, printer, floppy
disk, hard disk, etc.) as I would if I had bought
a stand-alone PC clone.
In answer to your specific questions:
1) I do not know whether the DOS Board "bogs down" the
bus when doing I/O. (I presume you are referring to
disk accesses.) To tell you the truth, I do not even
know whether the DOS Board accesses the hard disk
directly or passes requests to the hard disk driver
on the UNIX-OS side. I myself do not usually have heavy
jobs running on the UNIX-OS side at the same time as
an MS-DOS session. But I have never noticed any
slowness due to disk access. After all, a hard disk
is far faster than a floppy, and most MS-DOS programs
are written so as to run tolerably even directly
off floppies. In the case of my own 3B1 Computer,
the hard disk has an average access time of 28 msec -
two or three times as fast as a typical XT-class
hard disk drive.
2) The DOS Board is not, however, a perfect clone
of the IBM PC. Some incompatibilities I have run into
are:
a) The most obvious - no PC-compatible bus
slots. Peripheral boards designed for the
IBM PC cannot be used on the UNIX PC,
DOS Board or no.
b) Only Hercules graphics are supported -
no CGA, EGA, or VGA. Hercules is rather
popular in business and scientific circles -
it is still about the highest-resolution
graphics available. But only in monochrome!
Most commercial graphics software supports
Hercules, but almost no public-domain
graphics software does.
Naturally, character-based software (including
pseudo-graphics based on the IBM Extended
Character Set) runs fine on the DOS-73 Board.
One other important point: The Hercules
graphics on the DOS Board is only an
*emulation.* This has two consequences.
First, it's rather slow. (I think it's
usable, but some people would say it isn't.)
Second, public-domain programs that
purport to enable CGA graphics to run on
Hercules boards don't seem to work -
an emulation on top of an emulation is
apparently more than the DOS Board can handle.
c) The UNIX PC mouse is supposedly able to
work with some MS-DOS programs, but I
have not succeeded in doing this. Instead,
I have attached a Logitech mouse to the
RS-232 port that comes on the DOS Board
itself. The Logitech mouse is then as
usable as on a regular PC. In particular,
I have used it with PC Paintbrush.
d) The DOS Board does not have the same direct
access to the keyboard as on a PC. Thus,
certain unusual key combinations such as
Shift-PageUp cannot be generated, and certain
holding actions such as "hold NumberLock down
while using cursor keys" are not reproducible
or are not read by the program properly.
Luckily, the one program I have for which
this problem is the most serious, provides
its own solution: Intuit IS-2000, an
integrated word processor, spreadsheet, and
data base manager, uses some unusual key
combinations but it comes with a program
to customize the keyboard driver for a
particular machine's keyboard. Thus, I
was able to redefine Shift-PageUp to be
Alt-PageUp, which the DOS Board can generate.
e) The DOS Board does not come with BASIC.
I presume one can load a RAM-based BASIC
like GW-BASIC; but programs that require
a ROM-based BASIC like IBM's BASICA will
not run.
f) Some low-level operations are forbidden
or at least discouraged. For example,
the MS-DOS shipped with my DOS Board did
not include a FORMAT command. I do not
know whether the DOS Board is incapable
of formatting a floppy (I don't know
why this would be true; in other cases
it can access the floppy disk drive just
as a PC would) or whether AT&T simply
didn't want to give me two ways of doing
the same thing. (The UNIX Operating System
Software already includes a menu selection
for giving a floppy MS-DOS format.)
g) In connection with the preceding point:
I do not know whether I can install a
later release of MS-DOS (3.2 or higher)
on the DOS Board. It comes with MS-DOS 3.1.
One thing to point out is that AT&T does not guarantee
compatibility - in fact, the AT&T Hotline will not
give support for MS-DOS software on the DOS-73 Board.
3) I bought my DOS-73 Board during an employees-only
sale. Thus, I do not know where to get the best
price on the board, or what that best price would be.
Hope this information helps you make a decision.
Larry Mayka
AT&T Bell Laboratories
(312) 979-2766
ihnp4!ihwpt!lgm
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From: ...gatech!gt-eedsp!emory!kim
Organization: Math & Computer Science, Emory University, Atlanta
I have had a DOS-73 board for a little over a year. Initially I had
a lot of trouble with it and it didn't seem to work very well. It
turned out that I had a faulty motherboard (on my 3B1) and when that
was replaced it worked fine. It doesn't seem to load down the 3B1, but
if the 3B1 is loaded the screen in the DOS-73 board is slow. The only
really serious drawback is that the 3B1 screen is different than a PC
screen so that some programs require you to scroll up and down to display
the whole screen (there are function buttons to do this). The other
annoyance is that I have never succeeded in getting the 3B1's mouse
to work. I use this board primarily to run MS-WORD and have been
very pleased with it.
Please tell me if you find someplace that sells it for $300. Our
local Avnet sells it for $750 (I think I paid $1250 for mine). I'm in the
market for another board for my second 3B1 (cheaper than a service contract).
Good luck
Kim Wallen
Psychology Department
Emory University
Atlanta, GA 30322
UUCP: {akgua gatech decvax}!emory!kim
BITNET: kim@emoryu1
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From: ...cbosgd!cblpf!dtm
Organization: AT&T Bell Laboratories - Columbus, Ohio
I think even the retailers are selling the DOS-73 board for around
$300, but then I bought mine secondhand for about $275. As for the
compatibility so far I have mainly used it for turbo prolog, and it seems to
be quite ok. However it seems that it does to some extent slow down the I/O
when doing graphic output to the screen. good luck..
- D. Miruke
cbosgd!cblpf!dtm
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From: ...ihnp4!think!harvard!wjh12!gst
Hello again. I just came across your posting about the PC coprocessor and
wanted to ask you to either post a summary of whatever private responses
you might get or let me know what you find out. I was quoted a price
close to the second one you mentioned, and would, like yourself, like to
be able to get it for a lower price. In fact, that's the only way it would
seem worthwhile to me. I can't really say anything about compatibility,
as I've never used one, so again, I'd like to know whatever you learn.
Thanks much in advance.
Gary Trujillo
(harvard!wjh12!gst)
--
Lenny Tropiano ...seismo!uunet!swlabs!godfre!quincy!lenny -or-
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