test-drb February 2017

test-drb@ccmp.vtda.org

153 participants
189 discussions

by ard.p850ug1＠gmail.com

I am currently rack-mounting my PDP8/e and its peripherals. And of course I want to have the peripherals power up when I turn on the CPU. I have an 861 power controller in the rack, but you can't just link that to the power control sockets on the CPU, DEC changed the wiring at some point... Let me explain. The 3 pin power control sockets on the 861 and just about every other power controller and all my PDP11s carry the following 3 signals : Ground, On/ (ground to turn the unit on) and Off/ (ground to force the unit off, e.g. for an overheat shutdown). The 3 pin sockets on the PDP8/e CPU are not wired quite in parallel. One pin is ground. Another pin is On/ (as above). But the middle pins are linked via the frontpanel switch and overheat thermostat. The normal thing to do is to put a jumper in each socket so that one side of the switch is grounded, the other goes to On/. If you have more overheat thermostats in peripheral boxes, they can be linked into the chain. There is a mains output on the PDP8/e PSU that was (according to the printset) used to operate a contactor directly to power up the peripherals. A moment's thought made me realise you could use a normal power controller with the PDP8/e. The only disadvantage is that the overheat switch in the power controller would not shut down the CPU. Since I don't run my machines unattended that is no great loss. What I did was to cut a normal DEC power control cable (with the 3 pin plug one each end) in half. Call the 2 halves 'CPU' and 'Pwr' Then wire as follows : CPU/Green (Gnd) - Pwr/Green (Gnd) CPU/Red (On/) --->|--- CPU/Black (Switch) Pwr/Red (On/) --->|--- CPU/Black (Switch) Pwr/Black (Off/) : Not connected Now plug the ends into the power controller and one of the CPU power control sockets (make sure you have them the right way round). In the other CPU power control socket fit the jumper plug that links the middle pin to ground. The idea is that when the CPU switch turns on, both the CPU On/ line and the power controller On/ line are pulled to ground via the diodes. The diodes prevent the voltage from one power switching circuit ending up in the other. The diodes can be just about anything that will carry the power relay coil current. I used 1N4007's as I happen to have them to hand. I built it in a spare telephone junction box with 6 pairs of terminals. One set of terminals carries the cables. The other set carries the diodes and a wire between the 2 ground wires. Needless to say construction is not critical. It's very low speed, it's about 24V (and isolated from the mains) at < 1A. -tony

7 years, 10 months

FOR SALE: SWTPC 6800

by sellam.ismail＠gmail.com

I have a nice SWTPC 6800 with a color video board and custom sound board for sale. The ad is on the VCF forums: http://www.vcfed.org/forum/showthread.php?56190-SouthWest-Technical-Product… Please inquire directly to me via e-mail if you have any questions. Thanks! Sellam

7 years, 10 months

SWTPC 6800 for sale

by sellam.ismail＠gmail.com

I have a very nice SWTPC 6800 for sale. Please see the ad on the VCF forums for complete information. If you have inquiries, please do send them directly to me via e-mail. Thanks! Sellam

7 years, 10 months

need (physical) key for Sun SPARCserver 1000e

by Richard.Sheppard＠telus.com

Apparently the part number is 330-1651 http://docs.smoe.org/sun/feh/docs/wcd00015/wcd015cd.htm Richard Sheppard

7 years, 10 months

LMI Lambda?

by jnc＠mercury.lcs.mit.edu

> From: Alfred M. Szmidt > System 46 for the MIT CADR is licensed under a 3-clause BSD license -- > start hacking. ;-) You even have an emulator for the MIT CADR. Everyone seems to have blown right past this, but it might be important. Does anyone know if the Lambda matches the CADR? Or did they make changes ('improvements')? I always had the impression that it was basically a CADR clone. A CADR emulator, running the MIT code, would certainly be OK. Noel

7 years, 10 months

Odd-looking scope trace on an address line

by witchy＠binarydinosaurs.co.uk

Hi folks, Clear one problem and hit another is just what I expect to happen with this Executel :) After last weekend's little breakthrough my little machine is now hitting a loop that LOOKS like it's waiting for an RST6.5 interrupt*, but at the same time the A9 line is doing this: http://www.binarydinosaurs.co.uk/STCExecutelOddTraceA9.jpg (scale doubled for ease of viewing) That doesn't look normal to me, but all 8 chips that touch A9 check out OK and there's nothing odd resistance wise. Before I start chasing my tail again I thought I'd ask first... (*for anyone interested RST6.5 is triggered by the TS1/TS2 status lines from the MR9735 teletext decoder and should be constantly active while video is being output. At one point Tony suggested this chip needs to be initialised and there is indeed a control word that can be passed to it to turn it on and off which makes me wonder if there's another memory bit stuck somewhere) Cheers! -- Adrian/Witchy Binary Dinosaurs creator/curator Www.binarydinosaurs.co.uk - the UK's biggest private home computer collection?

7 years, 10 months

Unidentified (CDC?) panel

by cc＠informatik.uni-stuttgart.de

Hello, amongst other panels and things (CDC 6600 dead start panel, PDP-15 frontpanel) I got this one: http://up.picr.de/28257957bg.jpg I *guess* it also comes from the CDC 6600 but I'm not sure. Can anyone identify it? Christian

7 years, 10 months

11/44, parts, 11/24, DZ11

by useddec＠gmail.com

I have at least one 11/44 for sale, at least one 11/24 for sale. I can configure them as needed within reason. They can be packed and shipped as freight carrier of your choice or pickup in IL. or IN. Please contact me off list. Also the following parts: M7090 M7094 M7095 M7096 M7097 M7098 $300/SET (several available) 70-15672 backplane $70 M7093 FP11-A make offer M7819 DZ11 board only $50 Any quantity boards ship for $10 within US. Thanks, Paul

7 years, 10 months

The Biggin Hill Omnibus

by ard.p850ug1＠gmail.com

No, not Transport For London routes 246, 320, 464, R2 or R8 :-) Some of you might like the photos here ... https://www.flickr.com/photos/tony_duell/albums/72157677925921112 -tony

7 years, 10 months

tu58fs - PDP-11 file sharing with TU58 tape emulator, now RT-11

by j_hoppe＠t-online.de

Next milestone reached: tu58fs 1.0 now supports the RT-11 file system, additional to DOS11/XXDP (phew!) And its easier to use: I also precompiled binaries f?r Linux x64, Win32 Cygwin, ARM Beaglebone Black and RPi. Also some batch files show typical usage, XXDP/RT-11 tape and disk images are included. Docs on http://retrocmp.com/tools/tu58fs Precompiled releases at https://github.com/j-hoppe/tu58fs/releases The RT-11 filesystem has the special features of "extended directory entries" and "file prefixes". These are fully supported by tu58fs, but I never heard of real-life usage. Anybody can talk about it, or has RT-11 images with dir extension and/or file prefixes? best, Joerg

7 years, 10 months

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test-drb February 2017