test-drb December 2000

test-drb@ccmp.vtda.org

192 participants
490 discussions

by johnmalc＠conxion.gr

I have just acquired a Zenith Data Systems laptop, model number ZFL-184-01. It appears to be working ok but I have no software for it. It has two low density floppy drives, A and B, but will not boot to a Dos disk so I presume it requires some machine-specific software. If anyone out there can put me in touch with a website where I can download such software I would be very grateful. I specialise in keeping old machines running but this one has me beat. Thanks John Malcolm (in Greece)

25 years, 1 month

OT: wtd (uk) old chess computers

by stuart＠zen.co.uk

looking for old chess computer games, esp Vulcan electronics MKV. Please mail if you have anything. Thanks. stu

25 years, 1 month

OT: help...

by ajp166＠bellatlantic.net

From: Tony Duell <ard(a)p850ug1.demon.co.uk> >> This one uses only direct mains (160V). That bothers me less as it >> can't reach out abnd get me. > >That's fairly unusual (most manufacturers these days make PSUs that can >be adapted for use on both 115V and 230V). Doen't even have an IEC cord set, strictly domestic. mains come in through EMI line filters and gow through a bridge and cap hence the ~160V. >I'd still be careful of 160V DC at considerable current. It could be >fatal if you connect yourself across it. Personnally, I treat any voltage >over 50V with great respect. Don't have to tell me. I've been kicked mor than once by Oscope supplies and once by RCA VHF low (35mhz) 500W. >But insulation breakdown is relatively rare. There are a lot of >unpleasant voltages on the PCB tracks of most monitors just waiting for >you to touch them though. Which is why I maintain that in general the EHT >is the least of your worries. Some of them really spikey and feel bad too. >I would regard most monitors as being a lot safer to work on than valve >transmitters... No, most monitors these days can stand up without the cover and are mains powered. At least Valve Tx are transformer isolated and commercial gear well caged abd often interlocked. >Right. A total breakdown of the flyback can cause this as well There's >one winding connected from the main output of the PSU (around 100-150V) >and the collector of the HOT. There's normally at least one winding with >a tap connected to chassis. A short between them cna shut down the PSU. > >If it's not a short there, then a shorted vertical output IC will trip >the PSU in some monitors. I suspect the driving transistor to the HOT. >Some monitors, particurlarly multiple-frequency types have _separate_ >output transistors for the horizontal scan and the EHT generation, the >latter driving the flyback. Sometimes there are other transistors (or >MOSFETs) switching capacitors in the various output stages when you >change scan rates so as to retune the flyback. Shorts in any of the >semiconductors will shut down the PSU. sounds like this one. >> the test was to bridge the likely candidates.. no joy. > >I'd suspect _all_ aluminium electrolytics. I once had an Xterminal PSU It's not that old, maybe 6 years max. I'll poke some more but, at 130$ for a new{and better} one I'm not sure it's worth a lot of effort. Allison

25 years, 1 month

1 Question (CRT), 1 Suggestion (the list)

by webmaster＠ipom.com

Hey all, I have one question... one of the suggestions I received about my CRT was to resolder all the connections at the back of the CRT... and I was wondering... do I need to reheat the solder that's there, or do I need to take that solder off and put a new drop on? Also, to whomever run/owns the list... is it possible to get a digest version up and running. I'm relatively certain there is none currently, I searched the site a month or so back when I joined the list. Thanks. Phil -- Insanity Palace of Metallica www.ipom.com webmaster(a)ipom.com --

25 years, 1 month

Too much stuff in my basement series : DEC RX50-AA Rev.B Drives free/trade

by claudew＠sprint.ca

Hi Must get back some space in basement Too many of these here. I think I have 3. Maybe 4 Not tested. Good cosmetic shape. I dont wanna collect this type of DEC stuff. Going into garbage soon. Will give them away free or will accept anything that might interest me in return. I collect mostly 197x-198x micros. See my crappy website for more stuff to trade/give away (I dont want money) http://computer_collector.tripod.com Shipping from Montreal, Canada Expect shipping to be around $10CAN/$6US per drive approx. Claude Canuk Computer Collector

25 years, 1 month

Too much stuff in my basement series : 4 Apple Nubus 4/16 Token Rings cards free/trade

by claudew＠sprint.ca

Hi Once again way too much stuff here in my basement... 4 of these Apple Nubus Token Ring cards. Not tested. They look fine. Assy 670-4418 Will be going into garbage soon (next days) or will give away or trade for anything that can interest me. I collect mostly 197x-198x micros... See my crappy web site for more stuff to give away/trade... http://computer_collector.tripod.com Shipping from Montreal, Canada. Expect shipping to cost about $8 can or $5 US. Claude Canuk Computer Collector

25 years, 1 month

Software for Northstar Advantage 8/16?

by r_beaudry＠hotmail.com

Hello all, I recently acquired a nice Northstar Advantage 8/16, and manuals, but no software. Would anyone happen to have either Graphics/DOS or Graphics/BASIC for this machine? I have complete manuals for them, but no disks :-( Also, I heard that the Northstars use hard-sectored 5.25" disks. Is this true? Thanks in advance, Rich B. (I subscribe to the digest, so I can't reply immediately ....)

25 years, 1 month

VT78 - lots of questions

by pete＠dunnington.u-net.com

On Dec 30, 10:18, Jerome Fine wrote: > I have followed this thread, but I am still not sure what a VT78 does. > > Is it similar to a VT103 for a PDP-11? Well, "yes" and "no". It's basically a VT52 with extras which make it a sort of PDP-8, in the same sense that a VT103 is a VT100 with extras that make it a sort of PDP-11. However, there's no backplane, so you can't change the mix of boards (to use a different CPU, SLU, disk controller, etc); the layout is fixed and based around a Harris 6100 chip (roughly a PDP-8E on a chip, with some restrictions -- but I'm not a PDP-8 expert). It uses RX01 or RX02 floppies in a separate cabinet and runs OS/278 which is a modified version of OS/8 version 3 (I think?). I believe it's capable of running some other PDP-8 OS's too -- but I'm getting beyond my knowledge about there. -- Pete Peter Turnbull Network Manager Dept. of Computer Science University of York

25 years, 1 month

IBM-PC and SCSI

by ajp166＠bellatlantic.net

From: Richard Erlacher <edick(a)idcomm.com> >Well, Allison, you're memory's getting to be like mine. I've got three of >the 2266's and they all seem to agree they're about 1GB in capacity. Well, I knew it wasnt a 1mb drive as the smallest thing I'd ever seen as scsi was 10mb. >BTW, the drives don't seem to have a problem with the SCSI-1/SCSI-2 thing, >but the software, often written the way it is because the authors weren't >born before SCSI-2, don't realize that they get the same effect using the >SCSI-1 command set. As stupidly as SCSI is used on PC's, no overlapped >seeks, no command queuing, no disconnect, little use of synchronous mode, >they're not even getting SCSI-1 performance. No question about that. PC software and OSs generally dont use scsi well. My standard of comparison is PDP-11/RSTS or RSX and VAX/VMS where they work a disk hard! Allison

25 years, 1 month

VT78 - lots of questions

by djg＠drs-esg.com

>From: pete(a)dunnington.u-net.com (Pete Turnbull) > >Um, by your numbering scheme, 7 and 8 are H and J, not E and F. > Yup >> 40 pin connector is numbered >> >> 1 (A) 39 (UU) >> 2 (B) 40 (VV) > >ObNitpick: That's the reverse of the conventional numbering; Berg >connectors with letters have the red stripe at the A end, which is on the >left of the pin header (looking into the pins) while all other headers >which are numbered have pin 1 on the right. Yup, how about Looking into pins of 40 pin male connector numbering is 2 (A) 40 (UU) 1 (B) 39 (VU) I think both the numbers are letters were otherwise correct, just the summary diagram was wrong. I have put this information on my search page, http://www.pdp8.net/pdp8cgi/query_docs/view.pl?table=pdp8docs&id=146 I also added the VT78 to RX01/RX02 cable pinout This is the VT78 to RX01/RX02 BC80D-5K cable pinout (from buzzing out mine) Pins 1-9 of the DB25 go to pins 1-9 of the DB37 Pins 14-23 of the DB25 go to pins 20-28 of the DB37 Pin 25 of the DB25 is attached to the cable shield which is grounded at the other end with a wire to one of the mounting screw on the DB37. David Gesswein http://www.pdp8.net/ -- Old computers with blinkenlights

25 years, 1 month

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test-drb December 2000