test-drb

test-drb@ccmp.vtda.org

101090 discussions

by rodsmallwood52＠btinternet.com

Hello All Well I managed to find some suitable rubber tubing and glued it in place of the nasty black mess. So I put everything back and turned on. Lo and Behold LED on the board flashed once and stayed on. I had been told (Tony D I think) thats what its supposed to do. Anybody know whats the quickest way to test a TU-58? Rod

10 years, 2 months

PT-210 Serial Board

by dave＠661.org

A few years ago I entered the schematics and laid out a design for the serial board option for the TRS-80 PT-210 printing terminal using gEDA. I found the schematics in a hardcopy of the service manual[1]. I revisited the project a couple of days ago and reentered the schematics into Kicad. I remembered that the reason I never made the board was that I was unsure of its correctness. The schematics and foil patterns contradict slightly and a couple wires seem to be missing from the schematic. Does anyone here have a PT-210 with a working serial board? I would like to work with you to beep out various points so I can figure out what's wrong. I also found a Youtube video showing a PT-210 with the serial board in action. See https://www.youtube.com/watch?v=FPxpzcFXh-0 [1] Scanned and uploaded to http://chiclassiccomp.org/docs/content/computing/RadioShack-Tandy/ -- David Griffith dave at 661.org A: Because it fouls the order in which people normally read text. Q: Why is top-posting such a bad thing? A: Top-posting. Q: What is the most annoying thing in e-mail?

10 years, 2 months

80186 multi buss system problem

by grant＠millhouseindustries.com

Hi, I?m looking for some help diagnosing a old Grid server problem,I am a hobbyist learning my way around old computer systems . The system consists of three boards labeled Diagnostic server File server Com server Each board contains a 80186 , ram and rom and are all connected via a backplane. The diagnostic server has rs232 port and a connector to a small led display. The file server has a GPIB port and a something along the lines of a SASI port The com server has what i believe to be several rs232/422?s ports at least What i know works is the diagnostics server and the file server as i can interact with the diagnostic server via a serial terminal and the file server attempts to boot from a gpib floppy but i have no boot media that will boot it. The problem is with the com server board, when the system initializes the diagnostic board does a self test then looks for other boards on the system it finds the file server board but does not find the com server board. If i remove the the file and com server and power them out of system, reset the processor?s and then probe the different signals they appear to be operating the same,clk activity , data and address buss activity is identical. When i put them in the system and watch the file and com server boot it looks like the com server get stuck when it goes to send its data to the diagnostic server. I'm just a amateur at these things, i am looking for help to point me in the right direction. i made a small video of a typical data line at boot the first is the file server then the com server where you can see it get stuck , this is typical of all the signals that i test. https://www.youtube.com/watch?v=jHftWR0Ddys&feature=youtu.be --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus

10 years, 2 months

Random question about a Byte Magazine Cover

by mark＠wickensonline.co.uk

OK so this has been bugging me for a while. During a stint working at Morgan-Smith Electronics in Hatfield UK (they made diverse electronic systems including industrial PCs and radio alarms) I went through the boss's discarded vintage computer magazine collection and one particular issue I remember finding very interesting. IIRC it was a Byte Magazine (certainly the graphic was very in keeping with Byte cover artwork). I wonder if anyone recalls it - Google image searches have pulled a blank which means it either wasn't Byte (and just looked like it) or hasn't been scanned. The cover had a painted image of a white cliff face draped in vines with an 'Adventurer' in the foreground - you can imagine what the theme was. Anyone have any ideas? Maybe it wasn't Byte? Of course all this really quite irrelevant in the grand scheme of things, but it would help me scratch an itch at the very least. Thanks! Mark.

10 years, 2 months

Project Oberon and OberonStation (resend)

by wmaddox＠pacbell.net

[Yahoo's webmail client garbled the last link -- resending] The revived 2013 re-issue of Niklaus Wirth's Oberon system is a joy to behold.? If you've never heard of Oberon before, it is a minimalistic education-oriented language and operating system designed after Wirth had taken a (second) sabattical at PARC in the 80's. The new version runs on a custom RISC processor, implemented in an FPGA, instead of the NS3032 in the orginal Ceres workstations.?? Originally, it required a Digilent "Spartan 3 Starter Kit" with a custom-built daughterboard providing a few additional connectors.? This board is no longer made, however, and no other FPGA development board appears to provide the 32-bit wide fast SRAM the Oberon CPU required. Recently, a new board, the OberonStation,? has come onto the market that was designed specifically for Oberon, and will boot up Oberon 2013 out of the box.?? It also looks like an excellent platform for other retro-style FPGA CPU designs that want to stay away from complex SDRAM controllers and the caches they like to feed. My OberonStation arrived a couple of days ago, and it's really amazing to see what can be done with a hardware and software stack that is small enough to actually read and understand. https://www.inf.ethz.ch/personal/wirth/ http://www.projectoberon.com/ http://oberonstation.x10.mx/

10 years, 2 months

Purchased a Microvax 3800

by lyokoboy0＠gmail.com

I purchased a Microvax 3800 a few weeks ago. I have not really had the time to really take a good look at it until now. I still do not have the needed power cord to power it Up. Looks like a standard PC power cord with a notch in it. I found a place that sells them online, still waiting for it to get here. I was told the machine was removed from working service, however it looks like it has been sitting for quite some time. The hard drive, hard drive controller, and tape controller have been removed. I purchased a m7769 DSSI controller card online, so that is one more step in the direction of getting the machine all together. Still waiting to find the controller for the tape drive and a dssi hard drive, although they look to be pretty affordable on ebay. Just figured id post about it here, to show my progress twords getting it running. http://postimg.org/gallery/fztxjqbe/ --Devin

10 years, 2 months

double density floppy cable adapter for Intel Series II or III MDS

by spacewar＠gmail.com

Last month I made a trivial little cable adapter PCB to use with the Intel SBC 202 double-density M2FM floppy controller in an Intel Series II or III MDS (normally part of an MDS 720 subsystem). The usual SBC 202 cabling has two DC37S connectors on the MDS back panel, one for drives 0 and 1, and the other for drives 2 and 3. (There's a variant that has a ribbon cable to the internal drive as 0, and only one DC37S for drives 2 and 3.) Photos: https://www.flickr.com/photos/22368471 at N04/albums/72157659736489274 Schematic and board layout in Eagle and PDF: http://www.brouhaha.com/~eric/retrocomputing/intel/mds/mds-fd-adapter/ The adapter has no active electronics; it just wires a DC37P to a 50-pin header for a cable to one or two normal 8-inch floppies. I just got around to testing it yesterday, and was pleasantly surprised that my SBC 202 and the adapter worked on the first attempt. The SBC 202 was of unknown provenance so I didn't actually have much expectation of it working. I haven't yet tried more than one drive on it. Intel used radial ready signals from the drives, so the drive(s) have to be configured slightly differently than the factory defaults to be fully compatible with the MDS 720. I have one spare bare adapter PCB which can be made available for $5.95 plus shipping from Colorado if anyone else needs such a thing. I am NOT willing to source the connectors or assemble the boards. You can also order them in increments of three pieces directly from OSH Park: https://oshpark.com/shared_projects/AO0DZTr1 If there's demand for a few units, I can have a small run made in China very inexpensively, probably under $4 each plus shipping from Colorado. Richard Main has made fancier adapter PCBs that also support 34-pin cabling for the use of high-density 5.25 or 3.5 inch disks.

10 years, 2 months

Memory Voltage on MicroVAX II

by robert.jarratt＠ntlworld.com

I finally fixed my H7864 PSU so I can now run my rtVAX 1000. However, I think the machine is damaging memory boards. I checked the ripple and 5V looks OK, but 12V looks suspicious. Is the 12V supply used by the memory? Incidentally, as I have mentioned before, I have drawn out the schematics for the H7864 PSU. The schematics are drawn illogically, with mistakes almost certainly still there, but the Primary side I think is more reasonable now. Is there a good place to post these? Regards Rob

10 years, 2 months

TU-58

by anders＠abc80.net

> Date: Wed, 2 Dec 2015 12:40:08 +0000 > From: Rod Smallwood <rodsmallwood52 at btinternet.com> > To: "General Discussion: On-Topic and Off-Topic Posts" > <cctalk at classiccmp.org> > Subject: TU-58 > Message-ID: <565EE6A8.2030004 at btinternet.com> > Content-Type: text/plain; charset=utf-8; format=flowed > > Dear List > While the silk screeners process the panels I have a > couple of days for a little project > I have a TU-58 and yes it had gooey drive wheels. > Now it no longer has that problem but I have black and gooey fingers.!!! > > I know this issue has been addressed before. > So I think somebody must know where I can get the right tubing to > replace the degraded stuff. > The drive hub is 0.42" and the rubber bit was 0.62" o/d > A UK source would be nice, > > Rod > I'm also intessted in this. I have a dual TU-58 that belongs to my VAX 11/730 that need new capstan rubber. European source... /Anders

10 years, 2 months

I need to bring up a 11/20 shall I use a variac!?

by COURYHOUSE＠aol.com

I need to bring up a 11/20 shall I use a variac!? added core.... where can I find if I decide to add to it? ed sharpe _www.smecc.org_ (http://www.smecc.org/) (resent with address corrections)

10 years, 2 months

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