28 Jun
2001
28 Jun
'01
5:54 a.m.
Thousands of these were sold as bare boards with
limited doc's. I
frequently ran into folks using them, yet never saw one in the original
Xerox enclosure. The Xerox box was just too expensive. Once they were no
longer a major product, they were surplussed out as bare boards. I think it
was through BG Micro.
I got several of the bare boards in a lot of XEROX stuff that bought several
years ago. Haven't looked in those boxes in a long time but if I recall
correctly, the DOCS were *minimal*.
If someone really wanted them, I'd be willing to part with the boards.
SteveRob
----- Original Message ----- From: "Rich
Beaudry" To: Sent: Thursday, June
28, 2001 9:12 AM Subject: Xerox 820
_________________________________________________________________
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Hello all, > > Recently I acquired a Xerox
820, but as a single board,
w/ power supply. I > also received many docs
(including a tech manual with
Monitor listings and > schematics). I know originally these were
"all-in-one" computers, but many > appear at ham fests in exactly the same
shape as mine -- as a single board > computer. 
28 Jun
28 Jun
6:35 a.m.
I'm not sure where they are, at the moment, but I have a couple of
daughterboards that fit via cable into the 1771 socket but allow the use of a
179x device for double-density recording. I'm not at all sure that the 2.5 MHz
Z80 can manage the data transfer rate for DD 8" diskettes, but it's possible
that there's an associated update for the CPU that makes it possible. OTOH, DS
5-1/4" diskettes benefit greatly from DD recording. Unfortunately, I haven't
seen the one-page doc that goes with those boards in a long time, and I've never
seen the software update to support DD diskettes.
Dick
----- Original Message -----
From: "Steve Robertson" <steven_j_robertson(a)hotmail.com>
To: <classiccmp(a)classiccmp.org>
Sent: Thursday, June 28, 2001 11:54 AM
Subject: Re: Xerox 820
Thousands of
these were sold as bare boards with limited doc's. I
frequently ran into folks using them, yet never saw one in the original
Xerox enclosure. The Xerox box was just too expensive. Once they were no
longer a major product, they were surplussed out as bare boards. I think it
was through BG Micro.
I got several of the bare boards in a lot of XEROX stuff that bought several
years ago. Haven't looked in those boxes in a long time but if I recall
correctly, the DOCS were *minimal*.
If someone really wanted them, I'd be willing to part with the boards.
SteveRob
----- Original Message ----- From: "Rich
Beaudry" To: Sent: Thursday, June
28, 2001 9:12 AM Subject: Xerox 820
_________________________________________________________________
Get your FREE download of MSN Explorer at http://explorer.msn.com
Hello all, > > Recently I acquired a Xerox
820, but as a single board,
w/ power supply. I > also received many docs
(including a tech manual with
Monitor listings and > schematics). I know originally these were
"all-in-one" computers, but many > appear at ham fests in exactly the same
shape as mine -- as a single board > computer. 
10:07 a.m.
New subject: Anybody good at disassembly????
Hi,
Looking for anyone who is a major codehead that is really good at coverting HEX
code back to assembly. The code is for a long since obsolete PIC-1670 MCU and all
of the current disassemblers are for more current MCU's and not this off the wall
13-bit word beastie. Willing to pay a nominal fee if someone can do it, even if
your only in it for the challenge, somebody's gotta pay for the case of Coca-Cola
(or Pepsi if thats your choice) and the Twinkies to keep you on those all night
sugar highs to do the work :-)
Seriously though, I'm in a bind and could use the help if anyone is interested,
thanks.
Curt
7:35 a.m.
New subject: Anybody good at disassembly????
I remember back in the early days at IBM right before the 360 was announced
that they were talking in the industry of the possibility of a
disassembler. Most people poo-poo'd it as impossible. Datamation magazine
had a cartoon with a picture of a machine labeled disassembler with a
conveyer belt on each side. A worker was feeding cans of applesauce into
the machine and on the other side apples were coming out.
8:11 a.m.
New subject: Anybody good at disassembly????
On Thu, 28 Jun 2001, Gene Ehrich wrote:
I remember back in the early days at IBM right before
the 360 was announced
that they were talking in the industry of the possibility of a
disassembler. Most people poo-poo'd it as impossible. Datamation magazine
had a cartoon with a picture of a machine labeled disassembler with a
conveyer belt on each side. A worker was feeding cans of applesauce into
the machine and on the other side apples were coming out.
Maybe hindsight is always 20/20, but I don't see why machine code
disassembly would be viewed as an impossible task? I mean, weren't people
able to look at hex or octal dumps and translate them into the
corresponding mnemonics? This generally isn't a task that requires a high
IQ, it's basically a simple lookup operation. Hell, the problem is better
suited to computer based solutions than it is to people doing it.
-brian.
5:52 p.m.
New subject: Anybody good at disassembly????
--- Brian Chase <bdc(a)world.std.com> wrote:
On Thu, 28 Jun 2001, Gene Ehrich wrote:
Think of the machines in place when the 360 was king. The real problem
isn't the instructions, it's knowing where to put labels and what is data
and what is instruction (at least, in a Von Neumann machine, unlike the
Harvard Architecture of the original questor's PIC).
I have a disassembler for the 6502, written in PET BASIC. It's dog slow,
but it does work. Most of the trouble is at guessing where the labels
should go and keeping them straight.
-ethan
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I remember back in the early days at IBM right
before the 360 was announced
that they were talking in the industry of the possibility of a
disassembler. Most people poo-poo'd it as impossible.
Maybe hindsight is always 20/20, but I don't see why machine code
disassembly would be viewed as an impossible task? I mean, weren't people
able to look at hex or octal dumps and translate them into the
corresponding mnemonics? This generally isn't a task that requires a high
IQ, it's basically a simple lookup operation. Hell, the problem is better
suited to computer based solutions than it is to people doing it. 
9:25 a.m.
New subject: Anybody good at disassembly????
At 03:35 PM 6/28/01 -0400, Gene wrote:
I remember back in the early days at IBM right before
the 360 was
announced that they were talking in the industry of the possibility of a
disassembler. Most people poo-poo'd it as impossible.
They are not only possible but useful diagnostic tools. Using them is also
illegal under the millennium copyright act but that is a different rant.
For PIC architectures they are particularly easy because all op-codes are
single words and it is a strict Harvard architecture machine (separate I
and D spaces). Thus a dump of program memory, knowledge of the reset
condition (does it start @ 0 or 0x1fff) and a look up table and you're off
to the races.
--Chuck
11 a.m.
New subject: Anybody good at disassembly????
There are tons of disassemblers available for current moderm PIC MCU's, the
most popular being the PIC1684.
Curt
Gene Ehrich wrote:
I remember back in the early days at IBM right before
the 360 was announced
that they were talking in the industry of the possibility of a
disassembler. Most people poo-poo'd it as impossible. Datamation magazine
had a cartoon with a picture of a machine labeled disassembler with a
conveyer belt on each side. A worker was feeding cans of applesauce into
the machine and on the other side apples were coming out.
10:21 a.m.
New subject: Anybody good at disassembly????
Curt Vendel wrote:
There are tons of disassemblers available for current
moderm PIC MCU's, the
most popular being the PIC1684.
>Gene Ehrich wrote:
> I remember back in the early days at IBM right before the 360 was announced
> that they were talking in the industry of the possibility of a
> disassembler. Most people poo-poo'd it as impossible. Datamation magazine
> had a cartoon with a picture of a machine labeled disassembler with a
> conveyer belt on each side. A worker was feeding cans of applesauce into
> the machine and on the other side apples were coming out.
Jerome Fine replies:
I realize this will not help your specific problem, but I want to add that there
are two basic types of disassembler:
(a) Those that start from the final executable file - probably the majority
(b) Those that start from the OBJ file.
For the PDP-11, about the best program that I use is DECODE with a few
enhancements - the most important being the ability to allow an odd address
label in the case of an .Ascii text definition. Also helpful for RT-11 users
is a comment inserted when an expansion for an EMT macro like .LookUp
is found or .ReadF or many others. There is also the start of some code
to handle overlays, but not complete.
DISSAV is also available.
For the second type (b), there is UNMAC which also has some enhancements
that allow UNMAC to be applied to itself. Specifically, even though the original
source is in FORTRAN 77, the OBJ files can be put through UNMAC to produce
a *.MAC file that can be assembled via MACRO to produce a slightly different
OBJ file but which then LINKs to produce a final SAV file that is identical to the
original UNMAC.SAV file produced from the OBJ files that were produced by
the FORTRAN 77 compiler in the first place. Note that the original UNMAC
could not do that without substantial intervention by hand if at all.
By the way, while I realize that most members of this list are focused toward
hardware, the few of us who like software do not seem to mention it very
much, as if software is not important. Perhaps those of you who are the
hardware type could explain to me why the software holds so little interest.
While I agree that the hardware is needed to run the software (well not
actually anymore in the case of a PDP-11), I have never seen anything
useful from a system that has dumb software. But why does someone
feel that the solution is complete when the hardware is working?
Sincerely yours,
Jerome Fine
1:29 p.m.
At 12:35 PM 6/28/01 -0600, you wrote:
I'm not sure where they are, at the moment, but I
have a couple of
daughterboards that fit via cable into the 1771 socket but allow the use of a
179x device for double-density recording. I'm not at all sure that the
2.5 MHz
Z80 can manage the data transfer rate for DD 8" diskettes, but it's possible
that there's an associated update for the CPU that makes it
possible. OTOH, DS
5-1/4" diskettes benefit greatly from DD recording. Unfortunately, I haven't
seen the one-page doc that goes with those boards in a long time, and I've
never
seen the software update to support DD diskettes.
Dick
FWIW Those devices are probably used to update an 820 to an 820-II.
I'm not sure about the 820 but the 820-II supported both 5 1/4" and 8"
disks. The 820-II could format the 8" disks as SS-SD, SS-DD, DS-SD or
DS-DD. But the 820 only supported single density disk (SS or DS). On the
820-II the DD 5 1/4" disks held 155k or 322k (single or double sided) and
the 8" DD disks held 482k or 980k (single or double sided).
Joe
----- Original Message -----
From: "Steve Robertson" <steven_j_robertson(a)hotmail.com>
To: <classiccmp(a)classiccmp.org>
Sent: Thursday, June 28, 2001 11:54 AM
Subject: Re: Xerox 820
several
> years ago. Haven't looked in those boxes in a long time but if I recall
> correctly, the DOCS were *minimal*.
>
> If someone really wanted them, I'd be willing to part with the boards.
>
>
> SteveRob
>
>
>
> >----- Original Message ----- From: "Rich Beaudry" To: Sent: Thursday,
June
> >28, 2001 9:12 AM Subject: Xerox 820
> >
> >
> > > Hello all, > > Recently I acquired a Xerox 820, but as a single
board,
> >w/ power supply. I > also received many docs (including a tech manual with
> >Monitor listings and > schematics). I know originally these were
> >"all-in-one" computers, but many > appear at ham fests in exactly
the same
> >shape as mine -- as a single board > computer.
>
> _________________________________________________________________
> Get your FREE download of MSN Explorer at http://explorer.msn.com
>
>
>Thousands of these were sold as bare boards
with limited doc's. I
>frequently ran into folks using them, yet never saw one in the original
>Xerox enclosure. The Xerox box was just too expensive. Once they were no
>longer a major product, they were surplussed out as bare boards. I
think it
was
through BG Micro.
I got several of the bare boards in a lot of XEROX stuff that bought
4:25 p.m.
I have some doubts that the daughterboard from Denver Business Systems (now
defunct, methinks) that I have does nothing to help support 5-1/4" drives. Now,
I'm not familiar enough with the 820 boards that BG Micro distributed to know
whether they supported the mini-floppies.
Dick
----- Original Message -----
From: "joe" <rigdonj(a)intellistar.net>
To: <classiccmp(a)classiccmp.org>
Sent: Thursday, June 28, 2001 7:29 PM
Subject: Re: Xerox 820
At 12:35 PM 6/28/01 -0600, you wrote:
June
I'm not sure where they are, at the moment,
but I have a couple of
daughterboards that fit via cable into the 1771 socket but allow the use of a
179x device for double-density recording. I'm not at all sure that the
2.5 MHz
Z80 can manage the data transfer rate for DD 8" diskettes, but it's possible
that there's an associated update for the CPU that makes it
possible. OTOH, DS
5-1/4" diskettes benefit greatly from DD recording. Unfortunately, I haven't
seen the one-page doc that goes with those boards in a long time, and I've
never
seen the software update to support DD diskettes.
Dick
FWIW Those devices are probably used to update an 820 to an 820-II.
I'm not sure about the 820 but the 820-II supported both 5 1/4" and 8"
disks. The 820-II could format the 8" disks as SS-SD, SS-DD, DS-SD or
DS-DD. But the 820 only supported single density disk (SS or DS). On the
820-II the DD 5 1/4" disks held 155k or 322k (single or double sided) and
the 8" DD disks held 482k or 980k (single or double sided).
Joe
>----- Original Message -----
>From: "Steve Robertson" <steven_j_robertson(a)hotmail.com>
>To: <classiccmp(a)classiccmp.org>
>Sent: Thursday, June 28, 2001 11:54 AM
>Subject: Re: Xerox 820
>
>
> > >Thousands of these were sold as bare boards with limited doc's. I
> > >frequently ran into folks using them, yet never saw one in the original
> > >Xerox enclosure. The Xerox box was just too expensive. Once they were no
> > >longer a major product, they were surplussed out as bare boards. I
> think it
> > >was through BG Micro.
> > >
> >
> > I got several of the bare boards in a lot of XEROX stuff that bought
> several
> > years ago. Haven't looked in those boxes in a long time but if I recall
> > correctly, the DOCS were *minimal*.
> >
> > If someone really wanted them, I'd be willing to part with the boards.
> >
> >
> > SteveRob
> >
> >
> >
> > >----- Original Message ----- From: "Rich Beaudry" To: Sent:
Thursday, > > >28, 2001 9:12 AM Subject: Xerox 820
> > >
> > >
> > > > Hello all, > > Recently I acquired a Xerox 820, but as a single
board,
> > >w/ power supply. I > also received many docs (including a tech manual
with
> > >Monitor listings and > schematics). I
know originally these were
> > >"all-in-one" computers, but many > appear at ham fests in
exactly the
same
> >shape
as mine -- as a single board > computer.
>
> _________________________________________________________________
> Get your FREE download of MSN Explorer at http://explorer.msn.com
>
>
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