test-drb October 2000

test-drb@ccmp.vtda.org

184 participants
568 discussions

Red Erasors, contacts, and gold revisited

by b.layer＠vikingelectronics.com

>Anyone tried this snake oil^H^H^H^H^H^H^H^Hamazing substance? Quantum tunnelling eh? No comment :) FWIW, I am still a big fan of LPS-1, I've used it for years to clean & restore some of the most inconsolable antique potentiometers & switches. I would think that a greaseless lubricant of that type would be very happy on computer connectors.. As for erasers, I'm assuming that red pencil erasers are out due to their slight abrasive characteristics? what about the 'kneaded' erasers that chalk / conti artists use? (I'm not talking about Artgum ) Please let me know if this is bad thinking... Bill PS Thanks to everyone for posting the wealth of MDS background - I now feel like it was worth my time to drag this behemoth home. Hey, anything with a bank of switches & lights has got to be OK, right?

23 years, 9 months

PDP-8 question...

by ajp166＠bellatlantic.net

-----Original Message----- Mega thanks, that makes some sense looking at the board. I'd suspected something like that. Te ability to start on any 4k boundary is nice. The 74138 on one side and the '20 on the other should have screamed at me. Allison >The 16 pin DIP socket has a "black box" plugged into it. Hmm, popping >that box open reveals the expected jumpers. > >Looking down at the jumpers, the upper left corner is pin 1, upper right >is pin 16, I have 4 wires installed: > > pin 5 - pin 14 > pin 6 - pin 13 > pin 7 - pin 12 > pin 8 - pin 11 > >My board is set to cover fields 4 - 7. > >My guess would be that the 3 EMA bits are decoded into 8 lines, and are >present on pins 1 - 8, corresponding to DEC field terminology 0 - 7, >which makes obvious sense since pins 1 - 8 are on one side of the >DIP jumper, and that pins 11 - 14 are the individual 4Kx12 field >select jumpers. > >-Lawrence LeMay

23 years, 9 months

Fleamarkets (was Re: A LART is needed (was: VCF 4.0))

by John.Allain＠donnelley.infousa.com

It aint no VCF, but the last MIT Flea of the year is this Sunday! (IBM 5100 last seen: 1992, $200.00) http://web.mit.edu/w1mx/www/swapfest.html John A. (Didn't buy it. Fool!)

23 years, 9 months

IDE on Qbus (was Re: Microvax II)

by ajp166＠bellatlantic.net

From: Phil Budne <phil(a)ultimate.com> >> Has anyone designed a quick-n-dirty Qbus IDE adapter? > >see ftp://digital.dp.ua/DEC/ata/ Knew someone would look. ;) > ATA disk interface See above. > BOOT EPROM or Flash MRV11 with what you need in eprom or MXV11 M8189 11/23 takes eproms on the cpu. > Crystal CS8900 Ethernet DELQA > 512KW SRAM MS11 memoriesare out there. > SuperIO (ie; WinBond) > or > NS16550A (or eqiv high-speed, deep FIFO) UART for networking/kermit > Floppy ctrlr (capable of driving Shugart 8", 5.25" 3") Well the 16550 is basically a DZV-11, DHV11, that will get you a bunch of lines good to 38kb FDC for the mix if 3.5 or 5.25 is RQDX3, late rom. 5.25 is rx50(400k) and rx33(1.2m) 3.5 is rx23(1.44m) and rx24(720k) 8" is RX02/RX12. 256k/512k with 256k standard sssd 8" media and formatting. > ISA Bridge Why bother. Now if you wanted that all on a 8x9" board then I'd perk up my years. Allison

23 years, 9 months

Who collects (reads the mailing list...?) vintage computers

by ajp166＠bellatlantic.net

From: Eric Smith <eric(a)brouhaha.com> >The originally shipped a single-density FDC for 8-inch drives. It used >some NEC single-density only FDC chip that was *NOT* related in any way >to the uPD765 or the Intel 8271 or 8272. I don't recall the part number, >but it was almost certainly uPD and three digits. The uPD372... I have two of them. Allison

23 years, 9 months

48v dc power

by ajp166＠bellatlantic.net

From: Joe <rigdonj(a)intellistar.net> >>400ft, 10mhz clock for a S100 z80 system that was also distributed to >>other boards on the bus. A modification to the termination of that line >>virtually made it disappear, the standard terminators didn't actually >>match the impedence of the line making it antenna. Other hot one >>was the Altair you could hear the 2mhz anywhere in the house >>with the case on. > > Was that being ratiated via the AC power lines or the keyboard cable or >what? > > Joe The altair just radiates.... All the jungle wire fromthe FP to bus. There was no attempt to provide ground planes or decent grounding. None of the systems I mentioned would have a "keyboard cable". Allison

23 years, 9 months

IDE on Qbus (was Re: Microvax II)

by ajp166＠bellatlantic.net

From: Ethan Dicks <ethan_dicks(a)yahoo.com> >Has anyone designed a quick-n-dirty Qbus IDE adapter? If one is willing >to let the VAX processor do the work, it could be as simple as mapping >the I/O registers of the IDE drive into some I/O addresses. Not much >more than a few Qbus drivers and an address comparator, a la older ISA >IDE cards. It would probably heavily tax most CPUs, though. Some Russin person did. it's out on the net somewhere. As to taxing the older CPUs... How? IDE can do real slow, that's not much of an issue. Most of the VAX cpus do not handle interrupts very fast due to the huge overhead of context switch. But they can PIO in a loop fairly fast, that is to the limits of Qbus. Allison Allison

23 years, 9 months

Fixing a TK86

by cmcmanis＠mcmanis.com

Hello Everyone, I seem to be in possesion of a "broke" TF86 drive. As far as I can tell the only thing "wrong" with it is that it seems to have unhooked its "tongue" (the take up leader) and I've fixed that. Now I was wondering if there were any tests I could run on it before I tried putting it into a chassis to see what it does :-). It has a separate "bridge board" that converts its HD50 connector to DSSI. Some things I'm trying to ascertain: 1) Can I convert it to a TZ86 using the bridgeboard from a TK85? (they at least share connector similarity. 2) Is there any way to test it without hooking it to a DSSI bus? 3) Does anyone know the MOLEX part number for the 5 space DSSI power plug? --Chuck

23 years, 9 months

Red Erasors, contacts, and gold revisited

by dhquebbeman＠theestopinalgroup.com

> Hi > I also find it interesting to see the following app note: > > http://www.stabilant.com/appnt32h.htm > > I have never seen the problem they are talking about and > I have a sea going sail boat. According to their note, > this should be the worst condition. Makes me wonder > what I might be doing that is different than what > they are doing? Are you cleaning periodically with the silicone? Perhaps you're cleaning it often enough to prevent the silicate >from forming... -dq

23 years, 9 months

VMS with no documentation

by ajp166＠bellatlantic.net

From: Bill Pechter <pechter(a)pechter.dyndns.org> >The real fun on VMS is how slick EDT is with a good VT100/220. > If you think EDT is slick... try TPU or LSE after that Word will be intolerable. Allison

23 years, 9 months

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test-drb October 2000