test-drb December 2006

test-drb@ccmp.vtda.org

225 participants
420 discussions

by sdc695＠yahoo.com

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 __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com

18 years, 5 months

looking for HP 3000 37 CPU

by g-wright＠att.net

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

18 years, 5 months

updates to the Floodgap KIM-1 site

by spectre＠floodgap.com

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 ---------

18 years, 5 months

Computer Music

by wdonzelli＠gmail.com

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

18 years, 5 months

Advice for tape drive repair / maintenance

by aliensrcooluk＠yahoo.co.uk

--- 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

18 years, 5 months

Claude Shannon's "spooky hand in a box" toy

by hilpert＠cs.ubc.ca

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.)

18 years, 5 months

OT amends

by jbdigriz＠dragonsweb.org

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

18 years, 5 months

ebay seller computermkt

by trag＠io.com

>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

18 years, 5 months

Advice for tape drive repair / maintenance

by Billy.Pettit＠wdc.com

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

18 years, 5 months

The *meow* auction we've all been waiting for *meow*

by chrism3667＠yahoo.com

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! __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com

18 years, 5 months

← Newer
1
...
5
6
7
8
9
10
11
...
42
Older →

Jump to page:

2025

2024

2023

2022

2021

2020

2019

2018

2017

2016

2015

2014

2013

2012

2011

2010

2009

2008

2007

2006

2005

2004

2003

2002

2001

2000

1999

1998

1997

test-drb December 2006