test-drb December 2007

test-drb@ccmp.vtda.org

215 participants
420 discussions

by bnansel＠bigpond.net.au

I think I might have a whack at making R/W heads using small ferrite cores/beads, the kind used in radio work. My plan is to string several cores up on a straight brass rod with a snug fit to their I.D., then bed the whole lot in wax and remove the rod. Next I'll use an abrasive <mumble 1> to grind a tiny V-notch >from the inside of the cores, taking care not to break through the outer diameter. After removing the cores from the wax I'll wind <mumble 2> turns of <mumble 3> gauge magnet wire on them, fixed in place with super glue. Then I would re-bed them in more wax, this time with the coils down and the internal notches up. The cores would be almost completely embedded in the wax to provide strength for the fInal step, grinding a flat very slowly from the outside until the sharp end of the notch is exposed for each core. This makes the gap. I'll remove them from the wax and mount them on <mumble 4> blocks with <mumble 5> screw adjustments. As for the drum part, I think I'll be best off with a disk instead, perhaps a 14" washing machine platter and spindle from a 3000RPM <mumble 6> Gonkulator. So, aside from the mumbles, does this sound like a workable plan? -Bobby > Fri Dec 14 14:22 Gary Oliver go at ao.com said: > > I have a reference somewhere for a drum project from the 40s that used > what would now be simple machine-shop procedures (assuming one had a > small drill-mill and lathe) to fashion a small drum of a few k-bit > capacity. I'll try to dig that out and send it along. I was sort of > planning to do something along this line myself at some point during > "retirement" (which won't be for a few years, I suspect.) I've > acquired > a few of the components for fabricating the drum and will give it a > "whirl" some day. I was definitely NOT planning to make a flying head > device and to keep it simple enough I could fabricate a few heads from > "first principles."

17 years

xt/370 e-mail problem and stacked memory chips illustrated

by michaelryan＠mindspring.com

I have added a few new pictures to the xt/370 web site showing the stacked (and non-stacked) versions of the MCM66128L20, as well as two other examples of IBM engineering that employed stacked chips (AT motherboard and PC memory card) in the early 1980's. There are 36 pairs on the AT board to get 512K and 18 pairs on the memory card to get 64K. Obviously, these chips have different pinouts (at least select). The url is:- www.xt370.net click on the link to the left, 'Memory Technology' The question a data sheet might answer is:- does one of the new MCM66128L20 parts replace one of the old stacked pairs? --- also: -- >Subject: Re: Someone in search of XT/370 software >To: "General Discussion: On-Topic Posts Only" <cctech at classiccmp.org> >He's on the list. I have at least some of VM/PC, but when I tried to >email him to let him know, I got an autoresponse from a white-list >agent, which sent me to an unresponsive URL. It was sufficiently >irritating that I figured it wasn't worth pursuing further. >Seriously, folks, if you're going to ask for help, don't make it >impossible for people to give. >ok >bear Bear's criticism is well-founded. I believe I have corrected the problem; I did receive the e-mails and have responded off-list. At any rate, I greatly appreciate the interest and am sorry for the inconvenience. Mike

17 years

Homebrew Drum Computer

by ajp166＠bellatlantic.net

> >Subject: Re: Homebrew Drum Computer > From: ard at p850ug1.demon.co.uk (Tony Duell) > Date: Sat, 15 Dec 2007 23:29:12 +0000 (GMT) > To: cctalk at classiccmp.org > >> >> I thought of this, too. So far I haven't found an online source of >> them (Google search terms: "glass delay line" OR "quartz delay line" >> OR "ultrasonic delay line" TV PAL OR NTSC). > >I didn't think the NTSC system used a delay line at the receiver, but I >must admit I've never repaired a US TV set. Yes they did/do but is was not ultrasonic. The common ones were basically the same as LONG (4.5us?) transmission lines. They would be hard to find. Allison >It's not a common component for spares companies to stock, simply because >it rarely fails. And of course more modern TVs used IC delay lines, which >are not what we want here. > >When I wanted one, I went to an (alas long-gone) TV repair shop that also >sold compoennts. No, they didn't keep them in stock, but the owner found >a scrap PCB with a delay line on it. Needless to say that was acceptable. > >-tony

17 years

KayPro II keyboard schematic?

by ajp166＠bellatlantic.net

> >Subject: KayPro II keyboard schematic? > From: "Andrew Lynch" <lynchaj at yahoo.com> > Date: Thu, 13 Dec 2007 21:55:51 -0500 > To: <cctalk at classiccmp.org> > >Hi, >I recently bought a KayPro II keyboard. It contains a nice Keytronics >mechanical keyboard and really nice case. I'd like to convert it to a >parallel ASCII keyboard or just reuse its case but was wondering if anyone >had the schematics? > >Please let me know if you have the KapPro II keyboard schematics. Thanks! It has an 8048 uP if memory serves and the output is TTL level serial ASCII. Making it put out parallel would be a major hackup including reprogramming an 8748. Allison >Andrew Lynch

17 years

Quick survey

by cclist＠sydex.com

On 16 Dec 2007 at 9:06 dwight elvey <dkelvey at hotmail.com> > These are all 5.25inch. As far as I know, 10 sectored was > the most common. I don't know of any that used 16 sectored > and never heard of 9 sectored. The Vector Graphic systems all used 16-sector media and I've seen a few others systems as well. So, I'd be safe by generalizing that 8" 32-sector and 5.25" 10- and 16-sector covers just about all of the hard-sector media in common use? Does anyone know of any other "common" 8" hard-sector media? Thanks, Chuck

17 years

Small SBC kits for Christmas!

by cclist＠sydex.com

From: "Matt Lichtenberg" <kerobaros at gmail.com> Date: Sat, 15 Dec 2007 08:21:28 -0600 While not vintage (but then, is any modern kit really "vintage"?), TI has a very slick and inexpensive gizmo for their MSP-430 16-bit microcontroller. $20 bucks for a USB stick including programmer and processor; $10 for additional uC "heads". Might be a kick to fool around with: http://focus.ti.com/docs/toolsw/folders/print/ez430-f2013.html Cheers, Chuck

17 years

cctalk Digest, Vol 52, Issue 32

by cclist＠sydex.com

On Sat, 15 Dec 2007 10:36:39 +0100 (CET) > From: Christian Corti <cc at corti-net.de> > All the drums that I have seen have fixed heads. There are adjusting > screws for the distance between head and surface, but the head itself is > then fixed with another screw after adjusting (we had to do this on the > drum of our second LGP-30). Univac made extensive use of flying head drums during the 1960's. Systems as late as the 1108 used them. AFAIK, they all had "FH" prefixes to identify them as such. Bitsavers has the manual on the one I used on the 1108, the FH-880: http://www.bitsavers.org/pdf/univac/1107/UT-2560_FH- 880_Drum_Dec61.pdf IIRC, the FH-880 spun quite fast. On the other hand, the "big drum" on the 1108, the FASTRAND II, was a slow sewer-pipe of a monster. Here's a document that accurately describes it: http://www.fourmilab.ch/documents/univac/fastrand.html IIRC, the head movement was accomplished through an system of levers connected to solenoids that directly converted a binary code to a physical position. Regarding magnetostrictive delay line, bitsavers also has a collection of PB250 documents that might be worth a perusal: http://www.bitsavers.org/pdf/packardBell/PB-250/ Hope this helps, Chuck

17 years

Homebrew Drum Computer Delay Lines

by dkelvey＠hotmail.com

> From: bnansel at bigpond.net.au > > I've come across a reference to a reverb unit made with a garden > hose, speaker, and microphone. Would something as bone-headed as > this work as a data delay line? > > I've read that mercury was used in delay lines because it was a > better impedance match with quartz transducers, but wouldn't water > work nearly as well? Everything would need to be kept at a constant > temperature, and no doubt there would be some dispersion of the > compression waves. It's my understanding that a lot of materials > were tried for delay lines, but that mercury was the "best." > Hi The primary reason for mercury was the slow propagation time, not impedance. The slower, the more bits per length. Mechanical transformers are not all that hard to create. Early programmable calculators use a different mode of transmission. They use rotation of a wire. The twisting goes slower along the wire than a compression wave because it is the rotational inertia compared to the spring of the wire. Compressional waves tend to travel faster. In something like mercury, being a fluid, can only transmit compressional waves ( except other surface waves like ocean waves ). A wire can use either compressional or rotational. The rotational is slower and can hold more date for distance. The important thing for any of these is absorbing any reflection. This means that impedance matching and possible dampening will make all the difference. Surface can have vertical as well as shear waves but these are harder to control. The rotational wave is similar to a shear wave. Dwight _________________________________________________________________ Get the power of Windows + Web with the new Windows Live. http://www.windowslive.com?ocid=TXT_TAGHM_Wave2_powerofwindows_122007

17 years

any idea how to find old diamond edge 3d card?

by brad＠heeltoe.com

can anyone point me to a place to find an old "diamond edge 3d" graphics card? I specifically want one with the sega controller ports and a copy of virtua fighter. I looked on ebay - no luck. anyone have any ideas? any good places for ancient (like 1995) graphics cards? -brad

17 years

4004 and IC history / was Re: Vintage computer photogallery

by RodSmallwood＠mail.ediconsulting.co.uk

My memory may be at fault here but that sounds like it. A quad board ... I can't recall any yellow handles. It did have the standard DEC 20mA ASR 33 conector on a bit of short grey cable hanging off the top of the board. Other early sightings at DEC VT100 prototype . Wire wrap board mounted on a piece of thick plywood. Another similar bit of plywood on top with the monitor out of a VT52 perched on it. A third bit of plywood held the keyboard. A PSU (I know not whence that came) and an Intel MDS. (8 inch Floppy based in a blue box.) So I asked the inevitable 'Why all the wood' 'It doesn't short anything out came the reply' The design of the VT100 was done by one engineer who I met but I cannot recall his name. The case was the work of an industrial designer. We all thought the case was really smart LA36 prototype another wirewrap wonder with the print mech screwed to a board. LA180 prototype as LA-36 but with the wooden board clamped to the bench to stop it leaping about. Rod Smallwood -----Original Message----- From: cctech-bounces at classiccmp.org [mailto:cctech-bounces at classiccmp.org] On Behalf Of William Donzelli Sent: 18 October 2007 04:12 To: General Discussion: On-Topic and Off-Topic Posts Subject: Re: 4004 and IC history / was Re: Vintage computer photogallery > I'm sure I saw a development system at DEC for the 4004 running on a PDP-8 circa 1975. I think in its collection, RCS has a DEC Y187 card (the only yellow handled Flip Chip I have ever seen) that has a 4004 on it. -- Will

17 years

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test-drb December 2007