test-drb December 2007

test-drb@ccmp.vtda.org

215 participants
420 discussions

by technobug＠comcast.net

On Thu, 29 Nov 2007 12:02:05 -0700, J Blaser <oldcpu2 at rogerwilco.org>wrote: > In fact, a > couple of the PS PCBs went through the dishwasher to clean up the > remains to 'rodent residue'. On the whole, it seems that I got them > back together properly! ;) If there are any potentiometers on the boards that you washed, you might want to ensure that the wipers are making contact. Generally, pots are installed after a board wash unless they are sealed. An open wiper will cause many of the symptoms you are describing. An easy method is to measure the resistance across the pot and then the resistance from each leg to the wiper. The sum of the wiper to legs should equal the resistance across the pot. If the wiper appears to be disconnected, mark its position and then rotate the wiper through its travel and then back to the mark. If this fails to restore contact or the wiper contact is intermittent, replace the pot - it's not worth the effort trying to save a failing potentiometer. CRC

17 years

Using old disks drives

by wdonzelli＠gmail.com

> To some, I daresay, using a modern display on a classic machine borders > on heresy, like using a converter and a modern disk instead of an RP03, At some point, however, it starts to make sense. For these old 14" beasts, new/nice packs and heads are starting to get hard to find - some very hard. I have been looking for several types of IBM packs in new/nice condition for years now, with no luck. Same with the heads. And there are probably a dozen people waiting for a 18/36 bit RP06/RM03 emulator in a box, using a cheap modern disk. Prod, prod. (Looking for packs 1316, 3336, 3348, and heads for 2311, 3330. And the Univac equivalent to the 1316.) -- Will

17 years

Looking for source of S-100 backplane connectors

by mardy＠voysys.com

Does anyone know where one can still purchase S-100 backplane connectors? Thanks, -Mardy

17 years

ROM image for NEC PC-8300

by derschjo＠msu.edu

Anyone out there have a ROM image for the NEC PC-8300? This is NEC's variant of the Kyocera KC 85, of which the TRS-80 Model 100 was another. I picked up two of these a long time ago, they had been used as some sort of data-logging system and had custom ROMs in them which are useless without special hardware I don't have :). Now that I have a functional EPROM burner I can get this running in its native state, if only I can find the right ROM for it. Can't seem to find this on the 'net. Thanks for any pointers... Josh

17 years

VT100 Character ROM image

by dm561＠torfree.net

-------Original Message: Date: Tue, 4 Dec 2007 07:03:32 -0800 From: dwight elvey <dkelvey at hotmail.com> Subject: RE: VT100 Character ROM image >> From: derschjo at msu.edu> > >> > > I tried to dump the ROM over the weekend and had no luck whatsoever, > regardless of what I tried to read it as. I suppose it wouldn't be out > of the question to recreate the contents manually based on the patterns > from the tech manual; there's not a ton of data in there, it's just > tedious :).> Hi I've rarely seen ROMs that have 100% match between pin of a 2716. Most have at least one enable pin that is inverted. Also, to prevent damage, I recommend disconnection the program voltage wire with a socket adapter. This wire would be either tied high or low at the ROM depending on selects chosen for that ROM. On a 2Kx8 ROM, there are usually 3 enables that need to have the correct levels on. When I've read ROMs in the past, I've usually put SPDT switches on these wires. One can then play with the combinations to get the correct one that reads the data in the ROM. Dwight ---------Reply: Dwight's quite correct; many ROMs included partial address decoding. Aren't there schematics in any of the bitsavers files (or elsewhere)? Enable pinouts & levels should be obvious if you have a schematic; a lot less work than creating a ROM from the dot patterns... m

17 years

2.5" IDE to SCSI adapters

by justdun＠bigpond.net.au

Greetings all, I had heard thst someone was organising a group buy for 2.5" IDE to SCSI adapters (eg for Mac Powerbooks). I couldn't seem to find any reference in the archives. Can someone point me in the right direction? Thanks, Justin. -- ___________________________________________________________________________ Justin M. Dunlop NB: New email account details.... email: justdun at bigpond.net.au ____________________________________________________________________________

17 years

Mechanical calculators

by dm561＠torfree.net

Date: Tue, 04 Dec 2007 10:18:49 +0100 From: "Arno Kletzander" <Arno_1983 at gmx.de> Subject: Re: Mechanical calculators <snip> >Uhh, what have I done to deserve this treatment? You make me long >for those big ugly heavy boat-anchors even more than before. >Must...go...chastise myself (before my parents do when I bring home >the next one :-)) ---- Sorrrrryy... They're not "junk," they're "rare and valuable antiques," just a little larger than that old teapot belonging to your great-grandmother that your mother keeps in the buffet... ---- <snip> >My grandfather detested those, as they used 120V DC to pick the magnets >and there were lots of unencapsulated contacts within the mechanism... --- Ouch! Been there, done that... mike

17 years

Graphics for S-100 machines (MicroAngelo S-100 Graphics Board by SCION)

by dm561＠torfree.net

----------Original Message: Date: Tue, 04 Dec 2007 01:11:05 +0000 From: Pete Turnbull <pete at dunnington.plus.com> Subject: Re: Graphics for S-100 machines (MicroAngelo S-100 Graphics Board by SCION) On 03/12/2007 23:35, Richard wrote: > In the 79-81 time frame I remember poring over the ads for machines in > BYTE on a regular basis. (I really wanted my own computer but couldn't > afford one.) I recall that Cromemco and SWTPC both had some sort of > graphics options, although the SWTPC one might have been from a 3rd > party. Cromemco had the "dazzler" card IIRC. I have two Dazzlers, I think, and three Matrox cards for my Cromemco. They're not particularly common, but my Cromemco came from someone who supported various systems that needed graphics. -- Pete -----------Reply: S-100 Graphics are what got Cromemco started; the founders, Harry Garland and Roger Melen started out building RAM-chip cameras in their dorm room at CROthers MEMorial hall (CROMEMco) at Stanford and their Dazzler graphics card was quite a sensation in its day, stopping traffic and gathering a crowd when a New York computer shop set up a demo in its store window. Ironically, after years of selling high-end text-only S-100 systems to governments, institutions and business, in the end it was also graphics that kept them going (at least for a little while): A company called Dynatech (also makers of the famous Fuzz-Buster) was using Cromemco systems for one of their products, the Colorgraphics Weather System used by TV stations to display weather maps, and when Cromemco fell on hard times they "merged with" (were bought by) Dynatech to assure continued support for their systems. See: http://infolab.stanford.edu/pub/voy/museum/pictures/display/3-5-CROMEMCO.ht… mike

17 years

Graphics for S-100 machines (MicroAngelo S-100 Graphics Board by SCION)

by robert.stek＠gmail.com

No one was more surprised than me at the selling price - and I'm the one who sold it! I was expecting maybe $20 - $30. I think I even have another one, but I haven't found it yet. Anyway, it was a nice surprise and will mean some extra money for Xmas. Bob Stek Saver of Lost Sols

17 years

VT100 Character ROM image

by derschjo＠msu.edu

Anyone out there have a dump of the VT100 character ROM? (This is the ROM located at E4 on the VT100 PCB, labeled as 23-018E2-00) Over the upcoming holiday break I'm planning to work on my VT100 emulator (that is, an emulation of the VT100 hardware) when I'm not spending time with the folks; I have all the other ROM images but I'm missing this one. Thanks! Josh

17 years

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test-drb December 2007