16megs is the minimum to run W95 in my experience and it runs much better
with 32m. It's a pig.
<My P200 machine, when with only 32 meg, swapped itself to pieces it seemed
<after a few days since a reboot even though I'd shut down all unused apps
<to run one. System resources still were not released. After kicking up to
<64 meg I now can go for several weeks until needing a restart to recover.
It's called memory leaks. Seems some applications do not return resources
to the pool as do some win95 drivers. often it can be tracked to one bad
driver.
And to think my uVAXII is still running with the 9meg that I used to
service a half dozen users plus network activity.
Allison
Again, I have to agree about the "waste-of-trees" nature of most "technical"
documents these days. Nevertheless, I find it easier to understand the
result of a SPICE simulation when displayed graphically, e.g. with PROBE as
supplied with PSpice, as opposed to a 2-page long list of raw values. It's
true, SOME terminals, more recently than when I last bought one, but
nevertheless SOME terminals, were capable of graphic display. They just
weren't up to what a PC could do unless you paid more than what a PC would
cost.
I already stated that the "old" machines did the "old" and in many instances
quite persistent tasks well, and still would, given a chance. People have
learned, however, that it's not as beneficial to have OLD hardware as to
have new, not because of what it will do, but what it won't. I don't mean
that it won't break. Any hardware can fail. It's a statistical reality.
However, if you try to repair that old, fine, terminal you bought in the
'80's you'll find you can't get it fixed for less than the cost of a PC.
If, however, you break your PC, there's really nothing you can't repair or
replace for much less than the cost of the original.
Dick
-----Original Message-----
From: Tony Duell <ard(a)p850ug1.demon.co.uk>
To: Discussion re-collecting of classic computers
<classiccmp(a)u.washington.edu>
Date: Sunday, April 04, 1999 6:31 PM
Subject: Re: homemade computer for fun and experience...
>> What's happened over the years, however, is that people, having seen what
a
>> computer CAN do as shown in games, etc, have actually found ways to make
>> data easier to interpret, and perhaps to add meaning and emphasis to a
>> presentation, making it more persuasive, if not more informative, by
using
>> the graphical capabilities of a computer.
>
>Odd... I much prefer text to graphics for just about everything. Sure I
>like circuit diagrams. And graphs, of course. But I find the typical '4
>colour glossy' that passes for a technical document these days to be a
>waste of trees. I'd much rather sit down with an informative piece of text.
>
>> If you use a terminal, that's what you've got. There were, for a time,
>> attempts made at graphic terminals. These failed, however, because there
>
>AFAIK X-terminals are still in use....
>
>> weren't standards on which they could base their usage. Consequently, if
>> one didn't have certain hardware, there were limitations on the software
he
>> could use. Today, that's not the case, as EVERYONE has a PC clone with
at
>> least 1Kx768 pixels in 256 or more colors. EVERYONE has fairly ample
>
>Do they? I don't. My PC has Hercules and CGA graphics only. I don't own a
>VGA card (I might have an EGA card somewhere, but I don't use it).
>
>> Today, no one would normally consider a CP/M box for "useful" and
essential
>
>Depends on the 'useful work'. I've done seriously useful work on a Z80
>machine in the last year or so (admittedly running LS-DOS and not CP/M). It
>depends on what you class as 'useful work'. My old 8-bitters can still
>talk to the special interfaces I've designed to (e.g.) test cabling, dump
>ROMs, etc. Sure, I could use a PC. But have you tried getting the same
>level of docs for a PC-clone as I have for my TRS-80 Model 4? The latter
>is much easier to repair and keep running
>
>-tony
>
>
>The goal: 8 bit or 16bit, running from ROM's for software and store
>work files on HD, tape or floppy, text based on 6845 IC or similar.
>That is beggining, in the end should able to run CPM or something.
>I prefer to interface the PC keyboards to it as by make up the
>convertor to something that cpu understands by microcontroller or
>like.
Why restrict yourself to PC-clone keyboards? May as well just put a
serial port on it, that way you can use just about any terminal
with it and won't restrict yourself to specific hardware.
>I have so many TTL's and LSI's and some VLSI's, CPU's of all
>kinds (intel, Zilog and others), memories, different crystrals and
>oscillators. Should it be single board with everything on it in
>stages or do it modular via cards?
A CP/M-capable computer doesn't have to be very big at all these days -
there are several commercially available designs/kits/boards which
are a single PC board with just a couple of chips. The comp.os.cpm
FAQ gives links to several of these designs.
If I were you, I wouldn't restrict myself to what's in the junk box.
Total semiconductor price for a CP/M capable computer can be kept
to well under $25 using new parts. If I were doing it, I'd go surface mount,
just to see if I could do it in under 2 square inches :-).
--
Tim Shoppa Email: shoppa(a)trailing-edge.com
Trailing Edge Technology WWW: http://www.trailing-edge.com/
7328 Bradley Blvd Voice: 301-767-5917
Bethesda, MD, USA 20817 Fax: 301-767-5927
>Keep in mind, folks, that some of us remember when there simply weren't
>computers which we could use. Back when I was a boy, even the US GOV
>couldn't afford a computer capable of what my smallest simplest Windows9x
>system is capable. The fact that I don't use it for pure number-crunching
>is a recognition that there are other things equally deserving of the
>benefits of advancing technology. If a picture is worth a thousand words,
>then why type them if it's easier to draw the graphic representation.
>Moreover, if you have to read my 1000 words (about a page) and then draw
>yourself a graphic representation to understand and digest it anyway, why
>not stick to the graphic? A simple graphic can save both ends of a
>communication time, effort, and embarassment from when there's a
>miscommunication.
And a graphic display is a sure way to make certain that a human is
necessary at every step of processing, making it difficult to impossible
to automate many tasks. You can't search images for the occurence
of a particular object. Graphics are the first step to the point-and-drool
interface you find on just about every computer these days, where quality of
presentation is emphasized over quality of content.
--
Tim Shoppa Email: shoppa(a)trailing-edge.com
Trailing Edge Technology WWW: http://www.trailing-edge.com/
7328 Bradley Blvd Voice: 301-767-5917
Bethesda, MD, USA 20817 Fax: 301-767-5927
>"Buck Savage" <hhacker(a)home.com> wrote:
>> Actually, microcode is not compiled.
>
>All the microcode I've ever written was compiled. Of course, it was
>compiled from special source languages defined for that explicit purpose.
>No one with any sense would write a non-trivial amount of microcode any
>other way.
>
>> The i860 is a single chip implementation of the Cray-1,
>
>No, it isn't. Don't believe all the marketing hype you read; those guys
are
>paid to lie their asses off. The architecture isn't even *close* to that
of
>the Cray-1. In particular, the i860 is not a vector processor. It is a
>primitive superscalar processor, with a lot of the pipeline exposed to the
>programmer. It is tough to write a good compiler for it.
>
>> and provides just about the same throughput as the Cray-1.
>
>Almost, for some things. But not for heavily vectorizable problems.
For the HP 21MX, microcode looks like assembly language, so any tool
used for translation purposes is, by definition, not a compiler. It may be
that compilable languages are defined for the purpose of providing for
microcode but, that would mean that the sequence of microinstructions
is generally not predictable from the source code of the program thus
translated. Maximisation of processor throughput, and minimization of
microinstruction count, is at least half the purpose of microprogramming.
For such optimisation to be effected, on must necessarily write directly
in microcode, either bit and byte streams, or coded as in assembly
languages. In any case, the use of a language translator always
results in a reduction of process throughput.
Recall that microcode involves the establishment of timing signals
at critical control points within electronic circuits and, the selection of
data paths within those circuits. Given this fact, there seems little
reason to leave the efficiency of microcode up to the accuracy of
a language translator, which we all know to be generally less
accurate that the results obtained by a skilled human programmer.
I would be grateful to learn from you of the tools you used in the
preparation of microcode. All of the work I did was in graduate
school in the early 90's, and to date I have not seen a single
job made available to a microprogrammer type. I would really love
to have an opportunity to perform this kind of work as a job function.
As for the i860, sure, it is not actually the equal of a Cray-1 but, the
architecture is equal to that of the processor section of the Cray-1.
The chief difference in capacity lies in the memory architecture and
other support hardware, all of which is external to the processor.
The literature with which I am familiar regarding the Cray-1 states
that it can perform two multiplies, involving four different operand, at
a single machine clock cycle, and this is exactly the capability of the
i860. Further, I should like to know in what ways you deem the Cray-1
to differ from the i860, particularly with regard to the processor section.
Have you actually used the i860?
> Well, maybe it's donator's remorse, but I gave away my VT100's and 220's a
> long time ago. I never had any strong feelings about ANSI terminals, having
> lived without them for so long.
On the other hand, I've lived with them for decades, and couldn't imagine
being without them. They're the bread and butter of being able to
interface with a wide variety of software on a wide variety of platforms!
>What I would use is one of the simple display terminal routines available in
>the public domain. There are plenty of them which emulate ANSI terminals if
>that's what's wanted.
And 99.9% of them are lousy. (In large part because the current generation
of VT100 emulator writers have never even seen a real VT100, much less
actually read the VT100 spec.) For a comparison of many products,
both commercial and freeware, using an excellent test suite called
"vttest", take a look at
http://www.columbia.edu/kermit/k95compare.html
Another very excellent resource on the subject is at Rick Shuford's web site,
http://www.cs.utk.edu/~shuford/terminal/
--
Tim Shoppa Email: shoppa(a)trailing-edge.com
Trailing Edge Technology WWW: http://www.trailing-edge.com/
7328 Bradley Blvd Voice: 301-767-5917
Bethesda, MD, USA 20817 Fax: 301-767-5927
This is a sad but true artifact of the GUI. The best PC/Win95 backup
program I have trips all over itself because it wants a human response to a
query about whether or not to backup a file created by the backup program.
It's not a BIG file, and it doesn't hurt having it there, nor would it hurt
if it were left out. The default, however, and you can't get away from
that, is to ask. I surely wish that were the only such case.
Dick
-----Original Message-----
From: CLASSICCMP(a)trailing-edge.com <CLASSICCMP(a)trailing-edge.com>
To: Discussion re-collecting of classic computers
<classiccmp(a)u.washington.edu>
Date: Sunday, April 04, 1999 5:50 PM
Subject: Re: homemade computer for fun and experience...
>>Keep in mind, folks, that some of us remember when there simply weren't
<snip>
>>miscommunication.
>
>And a graphic display is a sure way to make certain that a human is
>necessary at every step of processing, making it difficult to impossible
>to automate many tasks. You can't search images for the occurence
>of a particular object. Graphics are the first step to the point-and-drool
>interface you find on just about every computer these days, where quality
of
>presentation is emphasized over quality of content.
>
>--
> Tim Shoppa Email: shoppa(a)trailing-edge.com
> Trailing Edge Technology WWW: http://www.trailing-edge.com/
> 7328 Bradley Blvd Voice: 301-767-5917
> Bethesda, MD, USA 20817 Fax: 301-767-5927
<I've got the 8/e frontpanel prints here. From what I remember the 8/f is
<a little different.
The displays are leds (minor change around that part), otherwise it's
identical to the 8e.
<THe frontpanel display logic is mostly built from diode transmission
<gates - this circuit
<
<In---->|-----+-----|<------+--- Lamp driver
< | |
<Sel-\/\/-----+ |
< |
<>From other gates-----------+
<for that lamp
Does not compute based on the chip part numbers.
<The MD inputs have their own set of gates. I'd start by tracing from MD1
<(pin AL1) through the diodes to the appropriate 380 lamp driver
<(E26/6,7,2 on the 8/e). My guess is an open-circuit diode...
Ther are very few diodes and the drivers appear to be 7404s with 74l54s
used as selectors.
Restate the problem... The display is the variable 12bit on off the
rotary switch and only occures when MD is selected. This suggests the
data selector logic or it's particular source on the board as MD on the bus
has the correct data.
<Oh, these old machines are quite easy to work on (famous last words...)
Generally the PDP-8 series is fairly straightforward.
Allison
Well, maybe it's donator's remorse, but I gave away my VT100's and 220's a
long time ago. I never had any strong feelings about ANSI terminals, having
lived without them for so long.
What I would use is one of the simple display terminal routines available in
the public domain. There are plenty of them which emulate ANSI terminals if
that's what's wanted. Just an ADM-3A or HAZELTINE-1500-equivalent function
set would be adequate.
Building in enhancements over what was done back when the computer was new
would not be my goal. I'm always into exploiting the fact that these
machines were once, and, hence, can still be, useful.
I'd emphasize that the computers we use today, fast and fancy though they
may be, don't really process text in a word processing vein much better than
they could 20 years ago. Likewise, if it rolled out the payroll in
accordance with both laws and schedules, it would probably still do that
today.
Dick
-----Original Message-----
From: Allison J Parent <allisonp(a)world.std.com>
To: Discussion re-collecting of classic computers
<classiccmp(a)u.washington.edu>
Date: Sunday, April 04, 1999 5:27 PM
Subject: Re: homemade computer for fun and experience...
><Admittedly, many folks seem to believe that a computer must have
><a video generator to be a "computer".
>
>Retrorevisionist PCism. Though a VC8E is a definate computer thing.
>
>< My CP/M experience started with
><Model 33 Teletypes and blinkenlights front panels, so perhaps I'm the odd
m
><out here.
>
>Same here. It's seems silly for me to recreate the logic and programming
>of my vt100 when I have a vt100 that works better than any I could put
>together. There is advantages to useing a PC keyboard and monitor as they
>already take space on my desk but then again I can provide a serial port
>and use the PC for a terminal.
>
>Allison
>
I have some reservations about your opeing assertion. I'd modify it to say
that articles are sometimes descriptions of circuits that work, sometimes.
I know people who build a circuit and try it once. If it works they say
they have the circuit working, and if it doesn't, they only say they have it
built.
There are fellows I know who seem to be quite competent at building
circuits, yet I see their stuff working and I see it malfunctioning, both.
Sometimes I believe their circuits/assembly techniues to be solid, sometimes
not. If I'm interested in applying a technology demonstrated in this
manner, I often try it myself, sometimes simulating it first, if I have
doubts about the validity of the underlying theory. The fact that a circuit
LOOKS good doesn't excuse you from performing the requisite analysis. I've
seen more error committed on the basis of inadequate analysis than probably
any other reason.
I seriously doubt, however, that anyone has written an article about
mounting two ISA cards on an S-100 board which occupies only a single card
slot when finished. That's what I was describing. I believe that's what is
needed, as opposed, say, to a multi-board interface, occupying, say, the
last position in a cardcage, thereby allowing cards to protrude somewhat
beyond the end of the cardcage. I'd consider that a believable approach.
The reason I say this is that the only way one gets to the notion I
described is by ordering the DIN 41612 connectors with their genders
reversed. Only a true dummy (referring to ME, of course) would do such a
silly thing.
I've got a basement full of circuits which didn't work though they were
copied from the application note. There are also a number which do work,
but I mostly delivered the working ones to someone who paid for them.
Dick
-----Original Message-----
From: Allison J Parent <allisonp(a)world.std.com>
To: Discussion re-collecting of classic computers
<classiccmp(a)u.washington.edu>
Date: Sunday, April 04, 1999 5:27 PM
Subject: Re: homemade computer for fun and experience...
><>Been there and done that.
><>Also, there are no less than two articles on how to go from s100 to ISA.
><>
><There's a substantial reach from an article to a solid and working circuit
><on a board capable of actually supporting the functions. This is
>
>The articles actually are descriptions of circuits that do work.
>
><particularly true since, now, the user is required to understand the inner
><workings of his own machine as well as those of the card he wishes to use.
><Having the usual inkling about ISA is not always sufficient.
>
>That was true then. Unlike PCs with plug and pray configuring a s100
>system meant you generally had knowledge and documentation or were plain
>crazy.
>
><><ISA cards on a single s-100 board. This would certainly be cheap enough
><><most cases, to warrant such an effort. The software might get to be a
><><problem, though.
><
><Yes, and therein lies the "problem" for the average user.
>
>define average user... today that's mom and pop that buy a PC and plug
>it in. Definatly not the case in 1980. The reality of older computers
>like the S100, SS50, Multibus types were you had to be a knowledgeable
>user. Or if that was a problem you went to Apple or TRS80 styled machine
>where the hardware was generally a fixed and software was the experimental
>arena.
>
>Allison
>
