test-drb September 2007

test-drb@ccmp.vtda.org

220 participants
406 discussions

by classiccmp＠memory-alpha.org.uk

> I'd love to see anyone write a self-modifying ROM ;-) Well, if the code was to reside in an EEPROM....LOL.... TTFN - Pete.

16 years, 7 months

9-track tape seals

by aek＠bitsavers.org

> I missd that, Who was looking for writeline tape seals? > I currently have several hundred along with several wrightlint tape racks I plan to put on ebay next week fro > a friend. I (actually CHM) has an urgent need for several hundred > I threw out close to 1,000 9 track tapes with > seals last week. And, as I recall, I had asked if you couldn't find anyone to take the tapes if I could get the seals from you.

16 years, 7 months

HP integral , 82297a

by jos.dreesen＠bluewin.ch

I seem to rember that people on this list ( Tony ?) have extended a 512K memory expansion for the HP integral. <<was it sufficient to stuff the open places on the PCB ? Jos

16 years, 7 months

9-track tape seal lifetime

by tshoppa＠wmata.com

Al made a comment about looking for Wright Line tape seals. A story of mine: In the 90's I got to spend a lot of time sitting in tape libraries filled with tens of thousands of tapes hanging on racks from the hook on the tape seal. During a typical stretch (say 8 hours nominal) one or two tape seals would break and the tape would get dumped to the floor. Sometimes the seal would break in response to some kind of vibration in the room (after all, there were several tape drives getting loaded/unloaded etc. as well as me rummaging through the racks looking for tapes) but other times they seemed to break with absolutely no reason. Sometimes the black plastic hanger would break but more typically the white plastic seal would break near the hanger. I'd say from this that out of a library of 30,000 tapes with several tape seals breaking every day, that the expected MTBF of those Wright-line tape seal is probably 30 years. That's not necessarily the same as lifetime. As the plasticizers dry out I'd expect them to break more often. Sunlight and ozone+ heat can really do a doozy on plastics. The hard-plastic IBM tape seals seemed to be very much more vulnerable to breaking in transport than the Wright lines, and they'd also occasionally fail just hanging there on the tape rack, but I'm reluctant to make any statistical statements about them because so many were obviously broken in transport.

16 years, 7 months

Hardware controller to emulate Ersatz-11's HD:

by jhfinedp3k＠compsys.to

This request is actually more than on topic since the software in question was written in 1995. Specifically, John Wilson wrote HD.MAC in 1995 as a temporary substitute for DU(X).SYS to use large (up to 32 MB) disk drives under Ersatz-11. Being a bit of an RT-11 nut (OK a lot of an RT-11 nut, addict), I finally enhanced HDX.SYS to use 22 bit addresses under the Qbus so that I could replace VMX.SYS after I noticed that using HDX.SYS was so much faster than both VMX.SYS (3 times as fast) and DUX.SYS (twice as fast). PLUS, my minimum version of the LOADed code for HDX.SYS is smaller than VMX.SYS, supports a full 65536 block RT-11 partition (sort of obvious vs less than 8192 blocks for VM: on the PDP-11) and also supports the commands: SET HD: NAME (allows an RT-11 user to COPY HD.SYS VM.SYS) SET HD: UNIT=nn (n = 0 to15) (allows the RT-11 user to specify the Ersatz-11 unit) SET HD: [NO]WRITE (allows the RT-11 user to make the disk RONLY) In addition, I have written code which executes at the user level which, under Ersatz-11, avoids the overhead associated with an EMT request and is twice as fast again as using the HDX.SYS device driver. Whereas: COPY/DEVICE/NOQUERY DU0: DU1: takes over 2 seconds, COPY/DEVICE/NOQUERY HD0: HD1: takes just about 1 second and my user subroutines take about 0.5 seconds to copy the same 32 MB RT-11 partition. Compare that with about 5 minutes for an RD53 to RD53 copy and about 4 minutes for an ESDI to ESDI copy (using either Maxtor or Hitachi drives) on a PDP-11/83. The comparison figures are for a 750 MHz Pentium III. I imagine that a 3+ GH Pentium 4 will be about 4 times as fast, maybe even faster using SATA 2 hard drives of (1 TB?). Well, no good effort goes unpunished and one thing led to another. I am testing other versions including support for 64 units under RT-11 and I have a solution looking for a problem. I know that a few people have discussed a Qbus controller for the PDP-11 to use the current large disk drives. Well, MSCP emulation might be the final goal, however, I would be VERY pleased to support the HD(X).SYS code for anyone who might want to develop the hardware to interface this almost trivial example of an interface to the PDP-11 which uses 8 IOPAGE registers as detailed by John Wilson in his hobby version of E11 in the source file HD.MAC, although there are 2 essential details omitted in the documentation concerning 22 bit Qbus operation and size requests. The key point is that John Wilson's interface (based on a Russian idea which used only 4 IOPAGE registers) is a simple as any concept might be needing only the byte count, block number and user buffer address for each read or write request. Finally, I will also suggest to Bob Supnik or anyone else who may be interested that SIMH might also make use of HD(X).SYS since the interface should be just as efficient under that emulator as Ersatz-11. Does anyone reading this agree and if so, is Bob Supnik the best person to make this suggestion to? Does anyone reading this have both the interest and the ability to write the interface code for SIMH to handle an HD: type of disk drive? Can you suggest who might be interested or have that ability. For myself, while I also use SIMH, it lacks two essential features: (a) Built in VT100 emulation (b) Is only about 1/10 the speed of Ersatz-11 Can anyone help with a contact address for Bob Supnik and anyone else who may wish to consider my request? Sincerely yours, Jerome Fine

16 years, 7 months

repairing really tiny traces

by dgriffi＠cs.csubak.edu

A friend of mine dropped a screwdriver into an open chassis and dinged two very tiny traces that are beyond his ability to fix. Is there someone in or around Portland, Oregon who could possibly fix this? -- David Griffith dgriffi at cs.csubak.edu

16 years, 7 months

Lilith success !

by jos.mar＠bluewin.ch

I have finally managed to extract the contents of my one remaining usable disk for the ETH Lilith. WIth this upper layer programs and the micrcode stuff I extracted earlier a Lilith emulator should become possible. Sadly the Lara wordprocessor resided on a bad spot on the disk and could not be rescued. I had to use Kermit on a 9600 baud serial line, this 5 MB took forever, certainly if you forget to set file type to binary and have to restart everything.... Jos

16 years, 7 months

Lilith success !

by aek＠bitsavers.org

> I have finally managed to extract the contents of my one remaining > usable disk for the ETH Lilith. That's wonderful news! I was able to locate the sources for the Modula-2 release that was distributed in 1981, which appears to have a Lilith back end.

16 years, 7 months

Looking for "Programming CalComp Electromechanical Plotters" book

by sellam＠vintagetech.com

CalComp published a book entitled, "Programming CalComp Electromechanical Plotters" in the 1970s era that contained documentation for software libraries for using the CalComp plotters. It's relatively obscure. The IBM 1620 Restoration Team at the Computer History Museum needs a copy for a project they are working on to interface a CalComp plotter to the 1620. If you've got a copy you can provide (all they need is a photocopy or scan) please contact Dave Babcock <dave at kaleidosoft.com>. -- Sellam Ismail Vintage Computer Festival ------------------------------------------------------------------------------ International Man of Intrigue and Danger http://www.vintage.org [ Old computing resources for business || Buy/Sell/Trade Vintage Computers ] [ and academia at www.VintageTech.com || at http://marketplace.vintage.org ]

16 years, 7 months

test, please ignore

by jwest＠classiccmp.org

Test message - messing with classiccmp mail server anti-abuse stuff. No response necessary. Jay

16 years, 7 months

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test-drb September 2007