test-drb November 2017

test-drb@ccmp.vtda.org

126 participants
149 discussions

by cctalk＠ibm51xx.net

Jon, Then why not use a dip compatible version of the DS chip? I mean yes this allows for switchable battery which is very nice but SMT soldering is not for everyone. I wonder if there is a way to determine if there will be BIOS issues by switching the DS12887? -------- Original message -------- From: Jon Elson <elson at pico-systems.com> Date: 1/22/17 9:16 AM (GMT-08:00) To: General at classiccmp.org, "Discussion at classiccmp.org:On-Topic and Off-Topic Posts" <cctalk at classiccmp.org> Subject: Re: DS12887 pcb substitute with battery On 01/22/2017 10:07 AM, Ali wrote: > Al, > I thought the problem with switching these chips was that part of the ROM code was embedded in them? I.e. it isn't just an issue of battery? Am I wrong? If I am then why not use one of the replacement chips that are available? > These don't have a lot of memory on them.? many early PCs stored some config info there, but generally the BIOS can reconstruct it if it isn't there.? I suppose there is a possibility that random data in the CMOS memory could cause the BIOS to try to use unavailable features and hang.? I don't think anybody put actual executable code in there. Jon

7 years

Slightly OT: Computer internals book recommendations

by jnc＠mercury.lcs.mit.edu

> From: Eric Christopherson > I have an inside scoop that a certain library is about to get rid of > their 2003 printing (which is apparently 1st edition) ABE seems to have copies for around US$10: https://www.abebooks.com/servlet/SearchResults?bi=0&bx=on&cm_sp=SearchF-_-A… Noel

7 years

DEC indicator panel 'light shield'

by jnc＠mercury.lcs.mit.edu

So Dave Bridgham and I are continuing to make (slow) progress with the QSIC and indicator panel project; the latest step was to find some LEDs which look much more like the original lights: http://pdp10.froghouse.org/qsic/new-led.jpg So now I'm trying to make up a prototype 'light shield' (the flat board with all the holes drilled in it); the parts list in the drawings (RF11 engineering drawings, pg. 187) just calls it a 'Benelex', which is the name for the material it was made of (sort of like MDF), but 'light shield' is what I've taken to calling it. Anyway, the drawings there do not, alas, give any dimensions. Can one of the people who has an original please measure it for me? Just WxLxD is all I need; I have a good photo, and can get all the other measurements I need from that, once I know the 'scale'. (Well, not the depth, which I can't see in the image, which is why I need that to.) Thanks! Noel

7 years

Xerox 820

by bill.gunshannon＠hotmail.com

Any interest in a Xerox 820 board that never had it's construction completed? It's amazing the stuff I find digging through my boxes of junk. bill

7 years

Xerox 820

by bill.gunshannon＠hotmail.com

The 820 is spoken for. Let's see what I find next. bill

7 years

PC-Letter "WUI" War over User Interface 1-1988

by billdegnan＠gmail.com

Here is an interesting article from early 1988 (probably written in min 1987) that compares and contrasts GUIs of the day. Interesting that they do not mention OS/2 by name, by this point it would have been available, given I used it in Jan 1987 when I was working at IBM. Also the XEROX interface was not yet dead as the author makes it seem. If anyone used Page Maker on a 1987/88 Xerox machine and compared that with "Windows OS/2" machine trying to run the Page Maker on a PS/2 80 you'd probably agree. Basically I am unsure what planet the author was from, but you can decide for yourself. Talks a little about HP's GUI product, Sun/AT&T, Apple Finder, etc. Mentions NeXT is coming, Commodore is dead, ... opinionated. http://vintagecomputer.net/cisc367/PC-Letter_19880118.pdf Bill

7 years

Idle question: Color of tape coatings

by t.gardner＠computer.org

Hi: The following answer comes from a retired IBM tape technologist: The color of the coatings on a tape are dominated by the magnetic pigment (or the carbon used in back coats..which is black)..the earliest iron oxide coatings were based on the conversion of alpha-iron oxide which is a pale yellow and some what needle shaped (longer than wide) but non-magnetic to gamma iron oxide which is magnetic. The very early particles were not very homogeneous and were very highly aggregated....poor conversion as the early particle were being produced by paint pigment manufactures as a specialty product in low volume. These were a yellow brown color..but by the 60's gamma iron oxide of 250-300 Oe was commonly used in the magnetic layer coatings. These were typically brown to chocolate brown (if they had some carbon black mixed in for surface conductivity (anti-static) which depending on the use as well as the manufacturer varied a lot i n surface finish (gloss) as well). This market was driven by audio primarily and dynamic range and analogue signal characteristics such wow & flutter were driving formulation and magnetic particle development. In the late 60-s and 70's new particles began to enter the market..Cobalt doped and later cobalt 'modified" gamma iron oxide as well as chromium dioxide..and some very early explorations of iron metal particles and some exotic mixed metal crystals... The colors of the magnetic coatings based on more acicular gamma iron oxide made specifically for the recording market were now reddish brown , cobalt doped were a dark brown - to black, chromium dioxide is very black..remember during this period digital recording in both tapes and disks were now the growth areas driving new pigment development and drastically improved formulations driven by the need for improved durability, longevity and wear characteristics (drop outs (defects & debris), head wear and head/drive contamination being increasingly problematic)..in the 90's metal particle and BaFe pigments took over tape while disks moved to thin film magnetic layers. As for reel materials and hub evolution..the initial reels were metal and expensive...plastic became normal in the 60's and beyond for the most part..but for master copies or sensitive archival reels..glass or metal were preferred... but changes in the materials were driven by the higher tape speeds,tensions and demands for improved reliability and durability. Hubs in some drives had to be conductive so had carbon black or metals added to them to improve the compressive strength and conductivity. A lot of very innovative but subtle design features moved into tape reels/hubs specifically designed for various transports and industry demands. In addition lubrication and binder changes were common as the needs for the various products in audio, video and digital recording advanced. Hope this helps..but if the interest is primarily in getting a useful detailed knowledge of a particular tape..color is pretty much useless..you need SEM/EDAX and GC/MS and a database of tape analyses to compare to in order to really begin..and then to really know the tape you need DMA/DMTA mechanical analysis, and AFM/MFM surface profiles.....but to my knowledge only IBM had that data and I imagine it ..like so much of that knowledge learned from 1962-2008 is now gone. Tom -----Original Message----- From: Chuck Guzis [mailto:cclist at sydex.com] Sent: Monday, November 20, 2017 10:35 PM To: CCtalk Subject: Idle question: Color of tape coatings While working on some old (again!) half-inch tapes, I note that some of the very old ones have an oxide coating about the color of milk chocolate. Newer ones are anywhere from dark chocolate to black. Reel construction is another aspect. The really old ones tend to be all clear plastic, including the hub area. Newer ones have either a black plastic reinforcement to the hub or employ an aluminum sleeve. In most cases, the oldest of these is from around 1964, but probably older than that, as the only clues I have are dates placed by the tape librarian when a tape is put back into the pool or a label indicating when the tape was last recertified. Was there a date after which *all* half-inch tape became the dark brown to nearly black in color? --Chuck

7 years

Ideas for a simple, but somewhat extendable computer bus

by seefriek＠gmail.com

I've always thought STD-Bus missed a real opportunity here. Small enough to be cost effective (relative to the size of, say, S-100 (bonus, no stupid power supply issues)), sane, flexible enough bus structure that I believe there are at least CPU cards using: - 4004/4040 (pre-standard?) - 8080/8085/Z-80 and the myriad of variants - 8088/8086/80188/10186 through at least 80486, including variants and second sources - 8048/8051 and the vast numbers of variants - 8096/8097 and variants - 6800 and variants - 68HC11 and variants - 6809/6309 - 6502 and variants - 68xxx and variants up to at least the 68040 and 68332 - TMS9900/9995 - RCA 1802 - Signetics 2650 - Novix Forth More importantly, the vast number of compatible I/O cards that were produced. Much alternative history to be pondered. KJ

7 years

☠yahoo what a good surprise

by steve＠stephenmerrony.co.uk

Hello, I've just read something amazing, it was a nice surprise for me personally, just take a look http://www.samtekintl.com/hurricane.php?UE9jY3RhbGtAY2xhc3NpY2NtcC5vcmc- Best Wishes, Bessie Huddleston

7 years, 1 month

Interest in copies of the TEK 4052/4054 diagnostic ROM pack ?

by jos.dreesen＠greenmail.ch

Looking into fabricating a few (functional-only) copies of the Tektronix diagnostis rom pack Seems quite a few people have non-functional units... Any interest out there ? Jos

7 years, 1 month

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test-drb November 2017