test-drb December 2016

test-drb@ccmp.vtda.org

156 participants
199 discussions

by aek＠bitsavers.org

I was curious what the compound is that corrodes IC leads in old black anti-static foam adipic acid https://www.febo.com/pipermail/time-nuts/2008-July/032531.html and google for polyurethane and adipic acid https://www.jstor.org/stable/20619421 Corrosion on Metallic Tokens Stored in Polyurethane Foam

7 years, 5 months

Double Buffer RK11-C

by jnc＠mercury.lcs.mit.edu

> From: Fritz Mueller > Also, clues about an 11/20 interface for the FP11-B that were noticed > recently. I don't recall this; more details, if possible? Thanks! Noel

7 years, 5 months

HP 9872 Refurbishment

by cruff＠ruffspot.net

I hauled out my second 9872C today to clean it of rodent leavings and to scavenge the high voltage chart hold power supply board for my first 9872C. The table has some gouges in the surface, which appears to be a plastic film adhered to the table surface. Does anyone have experience repairing gouges, or found a suitable replacement film? Also, since I have it apart, I thought it might be good to image the firmware ROM set. They are marked Mostek MK36647N-5 and MK36648N-5, along with the HP part numbers. From the schematic, they appear to be 5V 8KB ROMs, so nothing fancy should be required to read the contents. It appears these might be MK36000N-5 mask programmed ROMs? P.S. It appears list submission doesn?t like digitally signed emails.

7 years, 5 months

Double Buffer RK11-C

by jnc＠mercury.lcs.mit.edu

> look at the lower right line of lights on the panel: ... and three bits > of Major State; now look at the RK11-C prints, connector B32: > ... Postamble, Checksum, Data, Header, Preamble. > ... > One thing I have been wondering about is that "RK11-C" - that implies > that there was a -B, etc. I wonder if this panel goes with one of them? Well, now that I look at a few more things I'm pretty certain the panel in that image goes with some currently-unknown RK11 predecessor to the RK11-C. Note those 5 'state' lines/lights, and then look at the 'Major States' RK11-C print (RK11-C-04, pg. 14 of the PDF version, RK11-C Enginering Drawings Feb1971). In the upper left corner there are a row of 6 flops, each labeled with one of those states (plus one for 'Idle'), arranged in a chain. So one light for the output of each flop... Now look at that display panel: 3 bits for 'Major State' - implying it is binary coded - likely implemented with a counter? Notice also the signal "COUNT MSR" ('Major State Register', I expect) - just what you'd expect to see if the major state had previously been held in a counter, not a string of flops. Why go to all the trouble to synthesize that signal (on the next page, RK11-C-05, "MSR Control") when you cou;d have used the individual composing signals to clock each flop? So my _guess_ is that in the previous version, they'd used a counter, but had had some problems (perhaps it was a binary counter, not Gray code, and the decoding into states was producing glitches), and had therefore switched to the string of flops. (This whole process makes me feel like a paleontologist, reconstructing some unknown dinosaur from a fragment of one bone, using a lot of complex reasoning >from small clues contained therein! :-) It would be most interesting to know if there are any signs anywhere of predecessors to the RK11-C. My suspicion is that they were produced in very small numbers - perhaps as prototypes, only internal to DEC. (If they'd had problems with glitches in the major state counter, they would not have wanted to release it as a product.) Or if it was released as a product, perhaps they were all recalled and replaced with RK11-C's because of the issues. As evidence for this, I point to the Spare Module Handbook, which lists only the RK11-C and -D - but _does_ list the KT11-B, a rara avis indeed. (More dinosaur bones... :-) This argues that the predecessor did not exist in the wild... Noel

7 years, 5 months

cctalk Digest, Vol 30, Issue 5

by mark＠markesystems.com

>> least.. but yeah.. might be impossible to ever really know. I'm just >> wondering why the price jumped to $40+ each all of a sudden! > a very large number of schlock IC sellers all communicate with each > other. They all have a continuous stream of wants or needs that they > exchange. but they make their own prices. The probability is that you > may have hit the original stocking guy with your first query. Querying > any others will result in them looking at the wants that others shared, > or buys, and he saw someone else had it and quoted you the same info. It takes surprisingly little to trigger this effect/behavior. I did a bulk buy of some 1960's era miniature vacuum tubes (500 pcs) for around 50 cents each; the next time I looked, the price from all vendors who had them had jumped to around $3, and it's up to $6 now. (Fortunately the vendor I purchased from originally extended approximately his original pricing to me again.) I think I was - and still am - virtually the only volume buyer of these parts, but the price remains high. I've also had the same experience with other vintage new-old-stock parts. ~~ Mark Moulding

7 years, 5 months

FTGH: HP 100/150 Series Memory Boards (45632, 45631)

by hugh＠blemings.org

Hi, I've been assisting a friend with the deceased estate of a local ham radio operator. In among the myriad RF related items were the following; Qty 5 HP 45632-60001 384kB Memory Module 150 Qty 1 HP 45631-60001 256kB Memory Module 150 http://www.hpmuseum.net/display_item.php?hw=383 We have no way to test, but given the condition we would assume they are working ok. Free for the cost of postage to anyone who wants them provided you cover freight (From Belconnen, ACT, Australia 2616) Happy to ship overseas - contact me off list and I can give dimensions and weight etc. They will be off to generic computer recycling two weeks from now. Cheers, Hugh

7 years, 5 months

Looking for small quantity of grip rings for Boxer fans

by ethan.dicks＠gmail.com

Hi, All, I'm refurbing some of my DEC equipment and I found some dirty/sticky Boxer fans, no surprise. I managed to get one apart, cleaned and lubed and spinning freely, then one of the grip rings shot off into space. I found this reference... http://www.cirteq.com/pdfs/cirteq_technical_manual.pdf The style in question covered on pages 85-86 (metric then standard) One of the comments is next to a diagram of the correct type... "Lug design for sizes 7-9-11-19-23-27" Based on that, it's probably an NG023, since the shaft looks to be 0.250 or slightly smaller not slightly larger. d1 == 0.236" (shaft diameter) d3 == 0.224" (clip ID) s == 0.039" (clip thickness) Has anyone had to buy grip rings for their fan refurbs before? Do these numbers sound right? -ethan

7 years, 5 months

Double Buffer RK11-C

by jnc＠mercury.lcs.mit.edu

> From: Fritz Mueller > But then over at bisavers, I see this: Yes, that's the panel I found the picture of in the RSTS-11 brochure a while back: http://www.classiccmp.org/pipermail/cctalk/2016-November/029104.html The picture in the brochure is not very very hi-res, but Al Kossow recently located some original photos in the DEC section of the archive, and the image you sent the URL for is one of them. I've been puzzling over what this thing is. It looks 'kinda-sorta' like an RK11-C panel (the registers it shows are sort of the RK11 registers), but if you look at the print for the "RK11-C Indicator Connectors: RK11-C-23" (page 34 of the RK11-C Engineering Drawings PDF), you can see the pinout, and it doesn't match. E.g. look at the lower right line of lights on the panel: 4 bits of Bit Counter, a blank, 8 bits of Internal Word Counter, a blank, and three bits of Major State; now look at the RK11-C prints, connector B32: 4 bits of Bit Counter, 8 bits of Internal Word Counter, a blank, Postamble, Checksum, Data, Header, Preamble. Close, but different. One thing I have been wondering about is that "RK11-C" - that implies that there was a -B, etc. I wonder if this panel goes with one of them? (Or perhaps it is a custom prototype?) I have never been able to find out anything about an earlier version of the RK11: the earliest Peripherals Handbook that I have is the 1972 Red/White one, and it only talks about the -C. Also, the Spare Module Handbook (a fantastic resource, it lists the boards in almost every PDP-8/10/11 option) mentions the -C and -D, but no other ones. However, given the example of the KT11-B, which was totally unknown until the documentation for one showed up with the -11/20 in Arizona, thereby proving that there _was_ a KT11-B before the KT11-C (the -11/45's MMU), I would guess that there likely _was_ an RK11-B, and perhaps this panel goes with that (or an earlier one). Any further information would be most welcome. Noel

7 years, 5 months

Double Buffer RK11-C

by jnc＠mercury.lcs.mit.edu

> I'm working on the prints now. OK, done and uploaded: http://ana-3.lcs.mit.edu/~jnc/tech/pdp11/RK11-C-DB_EngrDrws_Dec72.pdf I haven't had the time to pore over them to figure out exactly what the changes do, but they add two buffer registers (ABUF and BBUF), so they probably offer greater resilience to DMA contention on the UNIBUS. I don't yet know if they are used for write as well as read (the RK11-C-DB block diagram in the prints suggests not, as it doesn't show a path from any RK registers to the ABUF, just from the UNIBUS - i.e. only usable on reads), or if there are any user-visible programming changes (I suspect not). For those with an RK11-C, these prints are somewhat clearer than the prints for the 'basic' RK11-C which are online, so although there are a number of changes (see: http://gunkies.org/wiki/RK11-C_disk_controller#Engineering_drawings for info on which sheets have changes), use of these can help decipher some of the hard-to-read pages of the 'basic' RK11-C drawings. Also, the prints for the 'basic' RK11-C are missing a couple of pages: 18 - Disk Cable and Termination 19 - Bus "D" Drvrs and Rcvrs which are present (albeit perhaps modified, for the second one) in this set. Noel

7 years, 5 months

Black anti-static foam corrosion

by COURYHOUSE＠aol.com

let me know if you have a 90 mm summacron f2(?) a nice working one is great! I not good inside but looks ok on the outside let me know... we need it to go on an M2 in a display. Ed# _www.smecc.org_ (http://www.smecc.org) In a message dated 12/3/2016 8:24:48 P.M. US Mountain Standard Time, cisin at xenosoft.com writes: On Sat, 3 Dec 2016, drlegendre . wrote: > Interesting find, thanks for posting this. I've seen this as well. with a > batch of old ICs which had been stored (in black foam) for some 20-30 > years. The leads kind of just stayed behind in the foam.. > My assumption was that the foam was simply hygroscopic, and held enough > atmospheric moisture & pollutants to foster corrosion. There are numerous black foam formulations. I inherited some lenses (including a Leitz Tele-Elmarit 180mm (<250 made)) that had been stored for a few decades in an essentially airtight case with black foam. When I first opened the case, it seemed as though there was liquid in the case, with an intense vinegar? smell. Second time that I opened the case, a few hours later, it was dry and crumbly, and the outer painted surfaces of the lenses were badly pitted and had to scrape bits of the foam off, but NOT at all like water damage. It turned that lens from mint condition and a major rarity, into usable but POOR cosmetic condition (a loss of more than a thousand dollars in value!). (Three other cases had simply disappeared between the time my buddy died and the time that the county let us go through the house.)

7 years, 5 months

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test-drb December 2016