test-drb December 2007

test-drb@ccmp.vtda.org

215 participants
420 discussions

by billdeg＠degnanco.com

> > >Well, I have the Exatron Stingy Floppy adverts on the back of (and >inside?) several issues of 80 Microcomputing which I could attempt to >photograph with my (cheap) webcam, if anyone is interested? > >No newsletters though :( > I have some of these materials if anyone is interested in PDF scans. Contact me directly and specify which issue of 80 Microcomputing and/or Newsletter (I have only the first @LOAD, the newsletter's name). I am presently working on a new drive belt replacement. I have found a vendor to make the belts and hope to get them in early January. It seems that every stringy floppy that I have come upon has a dried-up drive belt, making the drives useless. Before my last belt died, I was able to take a few pictures of a successful load: http://www.vintagecomputer.net/tandy/trs80_1/exatron_stringy_floppy/ Bill

17 years

Wanted: WATBOL for the PDP-11

by tiggerlasv＠aim.com

Has anyone seen sources floating around for WATBOL for the PDP ? Thanks in advance! Tim ________________________________________________________________________ More new features than ever. Check out the new AIM(R) Mail ! - http://webmail.aim.com

17 years

Wanted: System Industries QS1000 documentation / manual

by tiggerlasv＠aim.com

Greetings. . . I'm looking for documentation on a System Industries QS1000 SCSI controller for the Q-bus. I've tried the usual web searches, and checked out bitsavers and manx, to no avail. Any help would be appreciated. Thanks! Tim ________________________________________________________________________ More new features than ever. Check out the new AIM(R) Mail ! - http://webmail.aim.com

17 years

E: Shift Registers as Delay Lines (was Delay lines in TV

by RodSmallwood＠mail.ediconsulting.co.uk

Now that sounds familiar. Two for an 80 character line (8bits) 7 bits for the ASCII code and one for the extending under line cursor. 48 for 24 lines = six rows of eight on the board. Add address counters etc. Yup that could have been it. Rod -----Original Message----- From: cctech-bounces at classiccmp.org [mailto:cctech-bounces at classiccmp.org] On Behalf Of Steve Thatcher Sent: 20 December 2007 20:18 To: General Discussion: On-Topic and Off-Topic Posts Subject: Re: E: Shift Registers as Delay Lines (was Delay lines in TV actually Texas Instruments had a quad 80 bit MOS shift register package available in the early to mid seventies. I had used two of them for a frame buffer on a CRT controller design I did. The part number was TMS3409 I believe and it was something I got from the surplus market. -----Original Message----- >From: Chuck Guzis <cclist at sydex.com> >Sent: Dec 20, 2007 10:40 AM >To: cctalk at classiccmp.org >Subject: E: Shift Registers as Delay Lines (was Delay lines in TV > > From: "Rod Smallwood" <RodSmallwood at mail.ediconsulting.co.uk> > >> I actually worked on VDU's that used shift registers as the display >> memory around 1973.

17 years

Shift Registers as Delay Lines (was Delay lines in TV sets)

by RodSmallwood＠mail.ediconsulting.co.uk

The next VDU design after that was a sort of state mahine. Rod -----Original Message----- From: cctech-bounces at classiccmp.org [mailto:cctech-bounces at classiccmp.org] On Behalf Of Tony Duell Sent: 20 December 2007 21:58 To: cctalk at classiccmp.org Subject: Re: Shift Registers as Delay Lines (was Delay lines in TV sets) > > I actually worked on VDU's that used shift registers as the display > memory around 1973. > If I remember correctly one lines worth (80 characters) got > transferred to a buffer in the interline gap (Fly back time). The > buffer was scanned out in such a way as to address the character > generator one row at a time. Characters were 7x5 dots so the top five > dots of the first character was serialized followed by the top row of > the second one and so on. Then all of the second character row dots on > a line would be displayed until the end of the store (and therefore > frame was reached) The HP9866A thermal printer used MOS shift registers for character storage. I am tryign to recall the details, because it's not as obvious as you might think. From memory : The printhead is the full width of the paper, with 400 eleemnts (80 charas * 5 dots/char). Physically it's made up of 4 modules. IIRC each printhead module is divided up into 4 sectiosn, each of 5 characters, and I think they're interleaved (so characters 0, 4, 8,... are one section, 1, 5, 9,... are the next and so on. I might have got that wrong, though) Incoming characters (7 bit ASCII) are re-encoded to 6 bits (it's an upper-case only printer, so 6 bits is enoguh) and stored in 6 80-bit Shift registers (physcially 3 TO99 cans). When the printer dtects a LF character, the more comlicated parts starts up. This reads ou the shift retgisters, every fourth character is sent to the character geenrator ROM, and the bit pattern for the top row is shfited into a set of 5 (one for each column of the chracters) 20 bit shift registers (I think the chips used are 8203s) which drive the printehad. That pattern or dots is printed The shift registers are run rount again, now the next set of chars taken throgh the character gernearotr ROM. to the printhead shift registers, and printed After the top row of all 80 characters has been printed, the paper is moved up one dot-line, and the process is repeated, only this time the character generatoter ROM outputs the patterns for the second row of the characters. And so on until the complete characters have been printed. This is controlled by a state machine that looks simple as a schematic (a handful of chips), but is not easy to understnad! -tony

17 years

The 2N2/256-BSCP [was: Homebrew Drum Computer]

by bnansel＠bigpond.net.au

Thu Dec 20 2007 at 06:55 Dave McGuire wrote: > Well then you'd have the problem of defining "most powerful". By > many metrics, any VAX is an incredibly powerful system, but the > average > not-so-powerful modern PeeCee will blow its doors off in integer > performance. So how will you define "power"? > > -Dave Good question. Wish I'd asked it myself :) It could be any number of things. Myself, I'm going to eventually use it for a "simple" robot rover (more "museum piece" engineering ... it's a long story; ask me by private e-mail if you really want to know). Most people would probably do something different, though. Here's an idea: a machine powerful enough to serve a simple webpage with minimal graphics, a page views counter, and, oh, maybe a few links elsewhere. After all, these days Real Computers are all on the web, right :) I am not a web head, but it seems this ought to be doable. Shucks, if a Commodore 64 can browse web pages, this ought to be relatively straightforward. Sort reminds me of a guy I knew in the early '80s who recorded modem tones and about a page of 1200 baud bulletin board data on his answering machine outgoing message tape. He said it was to drive the then new phenomenon of computer hackers crazy.... -Bobby

17 years

More stuff to get rid of (terminals) [UK]

by classiccmp＠memory-alpha.org.uk

The clearout continues.... I've turned up a couple of Televideo 950s and a couple of Wyse 30s if anyone wants them? AFAIK The Wyse 30s are fully functional (though bear in mind I haven't used them for some 7 years), but I think the TV950s may need some TLC - I vaguely remember them having problems communicating with their respective keybaords the last time I used them (they'd make a good source of spares though). There's also a Zenith Z89 available, which definitely needs some work doing on it. Again, probably best used for spares for a working unit. All of these are available free for pickup from Birmingham before the end of January (whereupon any computer crap left in my house *WILL* be unceremoniously junked). BTW I've also turned up a number of old "Micro Decision" magazines from 1989/90 if anyone wants them (they were heading for the recycling bin, but with the amount of stuff I've chucked in there tonight they simply won't fit). They'll be heading for the recycler next fortnight, so speak up now if you want them! As usual, contact me off-list if interested. TTFN - Pete.

17 years

KayPro II keyboard schematic

by cclist＠sydex.com

> From: "Andrew Lynch" <lynchaj at yahoo.com> > Does anyone have a schematic for *simple* hardware only circuit using a > commonly available UART, like an 8251 or 8250, to do the serial to > parallel conversion? I am looking for a schematic which I can easily > modify to strap the UART to 300bps operation. If you don't want programmable logic, an 8251 or 8250 isn't going to be what you want. Try a TR1602 or TR1865 or any of the other "hardwire" UARTS--set parity, data bits, etc. by connecting appropriate pins to Vcc or GND; put the serial data in on one pin and take the parallel data out on 8 pins. No programming needed. Cheers, Chuck

17 years

Homebrew Drum Computer (magnetic heads)

by cclist＠sydex.com

Fred wrote: > That was less than 30 years ago. > Intro'd at 3rd West Coast Computer Faire? > (the one time that it was in southern CA) I used to get the newsletters from Exatron. I seem to recall (probably a sign of an impending ischemic event) that someone wrote a ditty in praise of their product and published it in one of those. Did anyone hang on to the newsletters? It started with "I love my Stringy Floppy..." or some such. > Actually, I think that he was referring to uses of empty 8 track cases for > ROM cartridges. Ah, so not magnetic at all and not germane to the topic. Cheers, Chuck

17 years

The 2N2/256-BSCP [was: Homebrew Drum Computer]

by bnansel＠bigpond.net.au

That's BSCP as in "Bit-Serial Computer Project." The 2N2/256 part of the name is a nod to ham homebrewer Jim Kortge (K8IQY) who designed a QRP rig called the 2N2/40 for a design contest about ten years ago. The contest objective was to design and build a functional amateur radio transceiver, using a maximum of twenty-two 2N2222 type transistors. Whether it uses drums, disks, or ultrasonic delay lines, my challenge is: 1) To build a complete functional computer, including memory, using no more than 256 2N2222-ish transistors (plus scads of diodes, resistors, etc.). 2) Use no ICs or other parts that wouldn't have been available to hobbyists ca. 1965. 3) Must be transportable in the boot of a mid-size sedan (i.e. a few roughly 350mm cubical modules). Anybody up for a contest to see who can design the most powerful general-purpose digital computer given these constraints? I guess we'd have to figure out what "powerful" means in this context, given that it's likely never to exceed a few KIPS. I'm prototyping DTL NAND gates and flip-flops today... -Bobby

17 years

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test-drb December 2007