Richard <legalize at xmission.com> said:
> The subject pretty much says it all... which character code did the
> 2741 typewriter/terminal use?
Short answer: Neither.
Long answer:
2741's came in two flavors, "correspondance" and "BCD" (someting close to
PTTC/8). The serial code transmitted is 6 bits and parity (total of 7 bits)
with start and stop bits. In PC parlance: 6E1. The transmission speed is
134.5 bps. Most baud rate generators actually have this speed.
The tricky part of this is that the 2741 communicates in HALF duplex. It has
character codes that turn the line around. On the terminal proper the <return>
key and the <attn> key. If you actually have a 2741, it might have manuals in
its back which describe some of this stuff (cryptically as I remember it). If
you want to release the typing mechanism, you can QUICKLY cycle the power and
it will release.
The difference between the codes is only the position on the ball and the
encoding of the keyboard. If you feel up to it, you can use the other type of
ball on the foreign machine. You need to send it the right codes. The
keyboard can't be changed, so if you have the wrong code, it types "wrong".
Why two codes? History.
Correspondance code was what they used when they coded the original typeball on
the selectrics (before they were used for computer I/O). They made the ball
that way to minimize thavel for frequently used codes and to not have pairs of
large letters (like M and W) next to each other. The BCD codes were used when
they adapted the units to computer use. IBM changed the keyboard coding on the
BCD units (there is some documentation on bitsavers) to correspond (bad word in
this context) to what they changed the typeball to.
Simple facts: The typeball has 88 positions. Two shifts, 44 in each shift.
There are 4 tilt positions and 11 rotate positions (neutral and 5 each way left
and right). At least that is the way on Selectric 1's and 2's. Selectric 3's
have 96 positions. Inside the typing unit, it takes 6 bits to make something
happen: Tilt-1, Tilt-2, Rotate-1, Rotate-2, Rotate-2A, and Rotate-5(minus).
The 2741 has codes (that don't type) much like an old 5-level teletype to do
shifts (upper case/lower case) and space. backspace, index (we call it line
feed) and return (CR and LF combined).
Just so you know: There is a symbol B134 in /usr/include/bits/termios.h on the
Linux box I'm typing this on. The speed is actually 134.5 bps. See the man
pages
Another wierd fact: Normal baud rate generators (and uarts) use a 16x clock.
For 134.5 bps this is 2152 cps. This is very close to a modem tone used in 103
type modem (2025Hz and 2225Hz). It can really screw up accoustic couplers (I
found out the "hard way"!).
Wierd fact: When IBM contracted with Qume for the units in wheelwriters, they
used correspondance code on their printwheels. Qume had an awful time since
some of the tines on the wheel had adjacent "high density" codes. Wierdness
compounded.
We now return you to the regularly scheduled mailing list for even more
trivia...
--
Tom Watson
tsw at johana.com
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Hi All
I have a broken HP 3000-37 and need a CPU board or ????
Anyone have spares laying around. This is the small foot-
print model. Looks like a HP 3xx desk top 680xx box.
Thanks, Jerry
Jerry Wright
g-wright at att.net
The reworked Floodgap KIM-1 site, including a new version of the KIMplement
KIM-1 emulator for the Commodore 64, is now available.
The new site includes a "FAQ"-style introduction to the KIM-1 with an overview
of options, software, hardware and emulation, along with a large link list to
document archives, software archives, hardware vendors and collector's sites.
In addition, the redesign also introduces version 0.2 of the KIMplement, a
true partial emulation of the KIM-1 running on the Commodore 64 (and no, this
is not a joke). KIMplement 0.2 supports:
- fully virtualized NMOS 6502 emulation with virtualized ROM and RAM access
and all documented instructions (no undocumented instructions on purpose)
- LED, keypad and SST emulation through partial RIOT emulation
- TTY emulation (using a simulated TTY modeled on the ASR-33) through partial
RIOT emulation
- KIM-4 emulation (16K addressable using emulated 4K and 8K cards)
- Load/save RAM to disk
- Built-in Revision E ROMs
This new version adds an extra 8K above $2000, fixes bugs with saving memory
to disk, improves emulation speed by overall ~25%, fixes glitches with the
TTY and makes the simulation more consistent, adds a disk wedge, adds the
ability to load binaries without starting addresses, and is precrunched to
half the size.
This is now compatible enough and offers enough RAM to run Tiny BASIC -- see
the screen shots. It's slow, yes, but it works! Other sample programs from
The First Book of KIM are also offered.
KIMplement will run on any modern Commodore 64 emulator, as well as any
real Commodore 64 or 128, of course.
Please let me know your comments and suggestions.
http://www.floodgap.com/retrobits/kim-1/
--
--------------------------------- personal: http://www.armory.com/~spectre/ ---
Cameron Kaiser * Floodgap Systems * www.floodgap.com * ckaiser at floodgap.com
-- Glory is fleeting, but obscurity is forever. -- Napoleon Bonaparte ---------
I am currently working on a project involving music made with
computers before MIDI. Some aspects and examples might be the old
mainframes playing tunes on band printers, minicomputers making tunes
with RFI, microcomputers controlling analog synthesizers, and so
forth.
I have no strict timeline on this, but I would like to pull things
together in a few months maximum.
Things I am looking for:
1) Recordings of 2nd generation (or even before, if they exist)
mainframes making tunes. There are a few recordings out there, and I
may be getting some help from CHM for more.
2) A working 1970s era minicomputer with core, probably a PDP-8 or
Nova, that is reliable enough to make a performance.
3) A 1970s era microcomputer controlling an analog synthesizer.
4) Outstanding examples of Atari and/or C64s making music.
5) Leads to artists and musicians that used classic computers in
recordings, famous or not. Decent quality MP3s would be great.
6) An example of the HP printer (a deskjet?) that contains the musical
Easter Egg, operational.
7) Any examples of music made by computer algorithms, remixes by
computer, and so forth. Experimental works are welcome.
8) Any suggestions to expand this. The computers need not be classics,
the music need not be oddball, but the results should be a little on
the weird side (for example, I do not need a Pentium 3 running
Protools making trance).
While I am not looking to buy any of these machines, I am looking for
examples that are very reliable, and can travel to New Jersey for a
Saturday morning (probably). Appearance is not important, being this
will all take place in a studio.
There is a very slim chance I can provide the minicomputer, but all my
tapes are lost in limbo, so I doubt it. Being a PDP-8/S, normal PDP-8
music tapes will not work. There is also a chance I can provide a
Minimoog synthesizer, if someone can provide the microcomputer with
D/A cards (for the control voltages) and some sort of software for
making a tune.
So please go and think about this, and tell me what you think, and if
you can contribute. Certainly proper credit will be given to those
that can help out, but sorry, no money. I am not getting paid for this
either.
Thank you for your time.
--
Will
--- Jules Richardson <julesrichardsonuk at yahoo.co.uk
> wrote:
**>> snip <<**
>
> The whole 'emissions at point of manufacture and
> disposal' does get
> conveniently forgotten by the majority of people,
> though. I think there's
> what, nine years of landfill left in the UK - afte
r
> which existing sites will
> be full and the law prohibits opening of any new
> ones. Yet there's virtually
> nobody either trying to reuse the technology that
we
> already have or making
> new technology that's long-lived and easily
> repairable.
>
> cheers
>
> J.
>
Is that true? (about the landfills)
I'm sure the government have already thought
of ways around that. The 2 I can think of
right now are:
1) Amend the law
2) Export our rubbish and pay for it to be
landfilled in Europe!
Certainly where I work we do alot more
recycling now. We always used to recycle
paper (or atleast, they have in the 8 years
I have been with them), but we also recycle
glass and cardboard (we get lots of stuff in
boxes in every week).
I'm not entirely sure how you could recycle
a car, per se. Obviously some of the internal
stuff can be taken out and reused, but aren't
cars made of different metals or are they
(each model) all made from the same metal?
(I'm not really knowledgeable about cars)
Regards,
Andrew D. Burton
aliensrcooluk at yahoo.co.uk
It being the frivolous season, a memory came to mind of Claude Shannon's
"spooky hand in a box" toy, or which apparently was sometimes called the
"Ultimate Machine". For those not already guffawing in an "I remember
that" moment, here's a description pilfered while I was searching the web:
Arthur C. Clarke in 'Voice Across the Sea':
"Nothing could be simpler. It is merely a small wooden casket, the size and
shape of a cigar box, with a single switch on one face. When you throw the
switch, there is an angry, purposeful buzzing. The lid slowly rises, and from
beneath it emerges a hand. The hand reaches down, turns the switch off and
retreats into the box. With the finality of a closing coffin, the lid snaps
shut, the buzzing ceases and peace reigns once more. The psychological effect,
if you do not know what to expect, is devastating. There is something
unspeakably sinister about a machine that does nothing -- absolutely nothing
-- except switch itself off."
(The one I remember was a plain black cube, not a coffin.)
It was a popular gimmick-toy / party-amusement in the sixties (I think I saw
it at Xmas/New Years time), but I haven't seen, heard or remembered it for decades.
I'm just curious whether they are still being made or are they all gone,
except perchance to find one at a garage sale (ebay?)? Is this recognisable to
anyone younger than ~35, or is it a forgotten amusement from the past?
What does this have to with computing? As stated it was devised by Claude
Shannon, in discussion with Marvin Minsky, and that should be enough, but I'd
also guess that it came out of thinking about things like the halting
problem, minimal machines, etc. (a machine that does nothing but halt
itself...). (Every computing museum should have an original one.)
I wish to apologize to the list for making potentially rancorous OT
references to religion and politics. They were over-general to begin
with, as I had in mind certain local land barons, robber barons, and
pave-the-planet suburban sprawl "developers" and franchise operators who
are anticipating their moment in the sun here locally, cashing in on a
Monopoly (and monopoly) end-game to the general detriment, to real
economic development in particular. Notwithstanding this, and
notwithstanding my opinion that the Religious Right is neither, this
ain't the place for it.
As for Mr. Florida, I wonder if he's ever read "The Yankee vs. Cowboy
War"? "W" as Hegelian synthesis? Off-list if you want to pursue this,
though.
Ob-cc: Wanted, recommendations on affordable, decent-quality steel
storage buildings, in the 2000-10000 sq. ft. range. Plus shelving,
workbench systems, etc. First responder please change subject heading.
Thanks.
jbdigriz
>Date: Tue, 26 Dec 2006 16:06:29 -0700
>From: Richard <legalize at xmission.com>
>In article <45916C11.95F67729 at rain.org>,
> Marvin Johnston <marvin at rain.org> writes:
>
>> [...] My guess (now)
>> is that computermkt has a pretty good handle on what an item *can*
>>bring, and
>> prices his stuff accordingly. [...]
>
>I don't see how an Atari 800 is going to bring $300 when they sell
>routinely on ebay for $30. (or whatever, insert actual price here.)
>
>He knows this because he'll *buy* the item from ebay for $30 and then
>turn it around and list it at $300.
>
>It looks like the majority of his stuff expires unsold and the stuff
>that is selling is best offer below his ask.
>
>He must have really cheap storage space, a ready supply of old boxes
>and lots of free time on his hands for this model to work effectivley.
This is a bit off-topic for the thread, but deals with the same
philosophy of selling question.
Sager had 128 pin 13 X 13 PGA sockets for $3 each a few years ago.
They have over 2500 of them in stock. I didn't buy any because I
was not about to start the project I have in mind for them. Now
they are priced at over $17 each. They still have over 2500 of them
in stock. As far as I can tell, they aren't selling any of them,
but they have upped the price by almost a factor of 6.
How does this business practice make sense? Can they take a larger
tax write-off when/if they dispose of them, if they list them at a
high price for a while? Surely any tax benefit is based on their
cost? Do they think a large corporate customer or the military will
suddenly find a desperate need for 68030 sockets?
The 128 pin socket fits the 68030 processor. I'm minded to
re-design the Daystar adapter for the Macintosh IIcx to physically
fit in the SE/30. But I would need a hundred or two of the PGA
sockets to make it a viable project. At $3 each it was doable. At
$17 each the cost of sockets would be more than what most folks would
want to pay (I think) for the finished product.
Jeff Walther
Tony Duell wrote:
At which point I have a device assembled with lead-free solder,
soldered at too low a temperature, so it gets dry joints within a few
months. With plastic mechanical parts made from the cheapest plastic
imaginable that make a freebie toy look solid. I'd be lucky if that $89
machine lasted for a couple of weeks after the warrenty period...
Now guess which I am going to do...
-tony
---------------------------------------
Oh so cynical for such a young man! I work with lead free solder every day.
And WD builds tens of millions of drives with it every quarter. All without
"dry joints within a few months".
So why do you assume that good engineers wouldn't change the temperature of
the soldering machines? Processes change constantly. And every major
producer of PCBs has had more than 5 years to move to lead free environment.
That was not a difficult change for competent manufacturing engineers to
make.
Yet, I think this is the third or fourth time you've brought this up. You
must have had a bad experience someplace and are judging the technology by
that experience. I know a lot of hobbyists, as well as lab technicians, were
annoyed at having to buy new soldering equipment for higher temperature
boards.
But the world has moved on. Lead free soldering is as good and in many
cases better than lead based soldering. On the data from more than 100
million lead free PCBs, I can attest dry solder joints are not a problem.
As for the cheapest plastic imaginable, I just don't see that in the
marketplace. My current assignment is working with DVRs, STBs and TVs using
disk drives. So I always have a couple of dozen units torn down on my
bench. What I see are vendors that have had 20+ years to refine their
design, their processes and their materials. I see components and systems
that have an order (or orders) of magnitude better reliability than the
products of 20 years ago.
This "everything old is good, everything new is crap" is not verified by the
data from the industry world wide. Some things do improve with time.
Especially in a cut throat competitive industry where warranty costs from
poor products will put you out of business in weeks. Customers (and in the
US, laws) demand reliable products. Companies don't survive if they make
consumer products that wear out in "a year and day". (Anybody here remember
that poem?)
Tony, you have your preferences and choices and more power to you. But if
you did a study of current state of the art electronics, you would find it
to be far superior to that of 20 years ago. Even if it won't provide a
maintenance manual.
Billy
WHAT THE MAC MIGHT HAVE BEEN reads the caption.
I haven't spent much time with muh Cat (that Cat
anyway ;), so I can't rightly say whether it featured
any enhancements over the old skool Macs. Certainly
not in drive capacity. I thoroughly welcome comments
though.
http://cgi.ebay.com/Canon-Cat-Computer-What-the-Mac-Might-Have-Been_W0QQite…
these things are seemingly pretty rare though. It
boggles me when I think that IIRC 20,000 or so were
made. Who would have the heart to throw one out!
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