test-drb October 2018

test-drb@ccmp.vtda.org

176 participants
160 discussions

Documation TM200 card reader - pinch roller restoration

by guykd＠optusnet.com.au

Previously: Manual for Documation TM200 punched card reader Restoration of the mechanics of my TM200 punch card reader progresses. There's a writeup here: http://everist.org/NobLog/20180922_data_in_holes.htm#tm200 Currently I'm machining a mold to cast new pinch rollers - and there's the rub (ok kill me.) The old rubber rollers were decayed to gunk, so there's no chance of measuring their original dimensions. >From the mechanics, if they were just touching the steel capstan rollers they'd have been 27.1 mm Dia. The mechanics has no adjustment or spring tension on the pinch roller positions. Their shafts are in fixed position, so all the spring is in the rubber of the rollers. Someone who recalls seeing one of these working, says the rubber rollers turned while the capstans turned, so they must have been actually pressing on them. But how much squish? Experimenting with a similar diameter silicone roller (from a photocopier) it semes like 0.2mm of 'squish' without a card, seems to give a good grip on a card. The cards are 0.1mm thick. That gives a resting roller diameter of 27.5 mm. Obviously too much 'squish' is undesirable since the roller would get permanently deformed when left idle in one position. The 2-part silicone I'll be using for first try at casting rollers has a cured Shore A durometer rating of 60. I'm hoping someone might have some knowledge of how much punch card reader pinch rollers should press against capstans. Does 0.2mm squish seem right, or am I way off? I can try multiple iterations, boring the mold out a little more to make the rollers bigger. But it would be nice to get it right first time. I don't yet have a TM200 manual, but the M200 manuals seem to cover pretty much identical mechanics. They give no dimensions for the rubber rollers, no mention of the contact pressure, or even diagnosing if the rollers are worn. There are significant differences in the electronics between the M200 and the TM200. I'm really going to need a manual with schematics once I get to debugging and interfacing the electronics. Bitsavers only has M200 manuals, and Al Kossow doesn't seem to have had any luck with > I'm pretty sure I just saw a paper copy of the TM200 manual > which is different from the M200. I'll have to dig around to > try to find it again. If anyone can suggest a source. I'd like to buy a paper copy. Which I'll scan and post at bitsavers etc. Guy

5 years, 9 months

GCC for pdp11

by paulkoning＠comcast.net

Gentlepeople, Once in a while people ask about GCC. It has long had pdp11 support, but it hasn't received much attention. Recently I've done some cleanup on it, and some more is in the pipeline. One notable new feature is that it can now produce proper DEC Macro-11 syntax output. It has long had a -mdec-asm switch, but that used to produce GNU output. Now it produces DEC output (and -mgnu-asm is how you get output for "gas".) The optimizer is better, and a bunch of compiler failures are fixed. Undoubtedly there are more bugs to be worked on. Oh yes, for grins I told GCC to build not just a C compiler but a C++ and Fortran compiler as well. That seems to work (but I get an error building the libstdc++ library). I now have C++ translations of the RSTS standard header files common.mac and kernel.mac, and the DECnet definitions in netdef.sml. :-) If anyone wants to give this a try, the best way is to get the current code via Subversion (see gcc.gnu.org for details). Alternatively, get a weekly snapshot; the DEC support is in the current latest, though some optimizer work will appear in the next one. paul

5 years, 9 months

Documation TM200 card reader - pinch roller restoration

by guykd＠optusnet.com.au

A quick update. Thanks to those who sent pics of intact rollers. Derived from those the correct pinch roller diameter is 27.20 mm. Notes here: http://everist.org/NobLog/20180922_data_in_holes.htm#rub It seems there's a few people who need new M200 rollers. Once/if I perfect a successful method of making replacements I'll offer them for postage and a few dollars. But I'm in Australia. Or, there's this guy in the USA: http://www.terrysrubberrollers.com/ Now the correct OD is known he's an alternative, with real rubber. (Maybe my end result will be rubber too. That remains to be seen.) I still haven't found a service manual for the TM200 (with schematics.) Guy

5 years, 9 months

Teletype cheap

by billdegnan＠gmail.com

https://www.ebay.com/itm/Teletype-Machine-Model-3320-3WA-Teletypewriter-AS-… b

5 years, 9 months

Bluebox AVR boards available

by dave＠661.org

I've finished my work on designing and debugging a PCB to go with my AVR-based bluebox program. Read about it and buy one at https://661.org/proj/bluebox/. This project implements a bluebox in C on AVR microcontrollers. This project is roughly a reimplementation of Don Froulas's PIC-based bluebox, which was written in PIC assembly. The resulting compiled program is intended to be loaded into one of the following circuit boards. Currently the code implements a bluebox, silver box (DTMF dialer with 4th column), redbox, greenbox, and 2600hz pulse dialer. There are 12 memory locations of 41 keystrokes each. -- 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?

5 years, 10 months

HP-Apollo 9000/425t RAM

by cmhanson＠eschatologist.net

I?ve come into an HP-Apollo 9000/425t which uses memory boards with 72-pin headers rather than using SIMMs. Based on what I can see in pictures online, the boards themselves don?t appear to be anything special (they just carry TMS444000 etc. DRAM) and the connections aren?t anything special either, so I figure it shouldn?t be hard to design a SIMM adapter. Does anyone have or know where I could find the pinout and timings? -- Chris

5 years, 10 months

RT-11 DY install

by dstalk＠execulink.com

I'm trying to use a simulated RX02 disk (under simh) with RT-11 and can't seem to get the DY driver to install. Here's the relevant log: sim> set ry enabled sim> att ry0 ry0.dsk RY: creating new file RY: buffering file in memory sim> c .install dy ?KMON-F-Invalid device installation DL0:DY.SYS .dir dy.sys DY .SYS 4P 20-Dec-85 1 Files, 4 Blocks 14841 Free blocks I've tried with 2 different software "kits", the one from the simh site and the one from bitsavers. Any ideas? Thanks, Don

5 years, 10 months

early ANSI C drafts, pre-1989 standard

by spacewar＠gmail.com

I'm interested in looking at any published drafts prior to the C 1989 standard. I found X3J11-88-090 here: https://yurichev.com/ref/Draft%20ANSI%20C%20Standard%20(ANSI%20X3J11-88-090… That makes mention of the previous draft being X3J11-88-001. Does anyone still have a copy of that draft, or other pre-89 drafts? I'm not looking for any of the published standards (I've purchased them), nor any drafts after the 1989 standard. Eric

5 years, 10 months

TU58 tape formatter (was Re: rebuilding DC100A cartridges?)

by shadoooo＠gmail.com

Hello. I have a VAX730 with both TU58 drives destroyed (capstan melted, need replacements). I also have a bunch of cassettes, but unfortunately all seem to have problems with the bend and/or bad spots on the tape. Possibly I would try to replace the broken bands (if I find a source) and/or replace the magnetic tape when damaged (I was thinking to try with audio cassette tape, don' t know if metal oxide high density tape could be good for it). Anybody has some information about the coercivity of original DEC TU58 tape? One problem indeed is the need of reformatting the tape, but: if I can emulate the TU58 drive using a serial, would it be possible to send raw commands to the drive using the serial and a PC? Andrea PS-If possible, some good-condition cassette would be very useful to me too. I'm located in Italy.

5 years, 10 months

IP address classes vs CIDR (was Re: Reviving ARPAnet)

by jnc＠mercury.lcs.mit.edu

> From: Eric Smith > which would respond to ARP requests for non-local addresses and reply > with the router's MAC address (on that interface), specifically in > order to make classful-only hosts work on a CIDR network. Yeah, Proxy ARP (an early RFC here: https://www.rfc-editor.org/rfc/rfc1027.txt but IIRC it was people at CMU who first came up with the idea; this RFC is >from people at UT-Austin, documenting it) was originally done to support subnetting (see https://www.rfc-editor.org/rfc/rfc917.txt for more) when it was first introduced - for hosts for which people didn't have the source, but needed to attach it to a subnetted network. Subnetting was a stage before CIDR (which took subnetting and Carl-Herbert Rokitansky's 'supernetting' and mushed them together). Noel

5 years, 10 months

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test-drb October 2018