test-drb December 2016

test-drb@ccmp.vtda.org

156 participants
199 discussions

by jnc＠mercury.lcs.mit.edu

> From: Glen Slick > You should also hang out at vcfed forum in addition to hanging out here. I barely have time to keep up with the things I'm already into (actually, strike that - I _don't_ have time to keep up already :-)! So I'm going to have to pass. Interesting about the FP11 stuff, though. I wonder, however, if those 11/20 mentions are more aspirational, rather than something that was actually done, and later dropped? I say this knowing a modest amount about how the KA11 CPU in the 11/20 works, and a bit about how the FP11-B interfaces to the host CPU. For one thing, it would take some modifications to the KA11 to recognize floating point instructions, so that it can wake up the FP11-B to handle them. But that turns out to be the easy part; it would take further mods to the KA11 because the FP11-B expects the host CPU to do data fetches, etc on its behalf. (See Figure 2-3 in the FP11-B MainManual.) This latter function can't be off-loaded onto a separate interface unit, as it needs access to register contents held in the CPU. I don't have the time to look into this further, but if someone is interested they'd need to study the FP11<->CPU interface, and in particular look at how the KB11 supports memory operations requested by the FP11-B - I wouldn't be suprised if there's some microcode in the KB11 to support those memory operations. Noel

7 years, 5 months

Intel C1101A

by vintagecomputer＠bettercomputing.net

Putting this out there for those hopefully in the know. I have been acquiring date-correct ICs and parts for my Mark-8 project, which is years down the line. I'm planning to build it on very carefully replicated clone boards, based off my originals. For my purposes, I'm trying to keep ICs early 1975 or earlier. Most Mark-8s that I've seen have P1101a plastic encapsulated RAMs. Most are Intel brand, but I've seen some that I think might be National or something.. they just say P1101A on top. The only source other than ebay that I have are those big chip vendors like Summit. And the problem with them is they aren't always precise about date codes. The P1101A, because they were produced for years, have a wide range of codes and the places I prospected them from couldn't guarantee 75 or prior. To my surprise, I found a few places had C1101A. They are white ceramic, gold legs. They have a 'batch code' of F1268. I got 16 of them for $14 each. I was going to get 32, but Summit also surprised me with 5 1973 vintage Signetics n8263s @ $25 each. I hadn't been able to find any pre-1980 so I snatched those.. but that put me beyond a budget where I could buy 32. I figured I'd buy 16 chips for now and then buy another 16 the next month. Now of course, the chip houses have turned tables on me. They want $48 per chip instead of $14 like last time. And checking around, that seems to be uniform. Now, I'm not averse to paying that, though it will sting. But I want to make sure my assumptions are correct.. that these white vintage ICs are in fact pre-76. Can anyone confirm that? The info out there is a little vague. And would it be totally out of place for C1101as to be on a Mark-8? Could a hobbyist have had a source for them, beyond having some lying around?

7 years, 5 months

UNIBUS/QBUS interface chips Was: Re: MEM11 update

by jnc＠mercury.lcs.mit.edu

> From: Pete Lancashire > Do you or someone have a list of all the Unibus bus chips ? I have seen the following bus interface chips used on DEC UNIBUS boards: Drivers: 8881 - Sprague, Signetics - Quad NAND Receivers: 380 - Signetics - Quad NOR 314 - Signetics - 7-input NOR 8815 - Signetics - 4-input NOR 8837 - National Semi - Hex receiver (aka Signetics N8T37) 8640 - National Semi - Quad NOR Transceivers: 8641 - National Semi - Quad transceiver The actal complete part number can vary depending on the manufacturer; e.g. the 8641's are usually DS8641N, from NatSemi, and the 380's are usually SP380A's or SP380N's. Where the basic number is not included (as with the 8T37 for the 8837) I have given it. The following chips have been used by DEC to interface to the QBUS, and I have seen many of the above chips (e.g. 8641's) used there too, so I think chips seen on one bus could be used on the other: Drivers: 7439 - Various - Quad NAND Transceivers: 2908 - AMD - Quad latching transceiver with tri-state output I _believe_ the following chips are also usable as UNIBUS/QBUS interface chips, but I'm not sure if I've seen one used there: Transceivers: 8836 - National Semi - Quad NOR 8838 - National Semi - Quad transceiver (aka Signetics N8T38) Quite a zoo! Noel

7 years, 5 months

Intel C1101A

by jnc＠mercury.lcs.mit.edu

> From: Mark Moulding > 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 There is another possibility (one which I think I saw happening when Guy and I were buying DS8641's, which we previously discussed here), which is that if multiple vendors have stock, an initial order might buy up the ones with the cheapest price, and a second order will wind up being met from a different dealer's stock, one with a higher price. Noel

7 years, 5 months

Is there a magic word to format a 8" Altos hard disk?

by aek＠bitsavers.org

Picked up an Altos 8600 that I bought on eBay yesterday, amazingly the Xenix actually came up, but the drive failed as I was tarring off the file system. I had another Quantum 2040, put it in, tried to run the formatter, but it says to call Altos, asks for a confirmation but just returns to the menu if you type 'y' 'Y' or 'Yes' so I'm assuming there is a magic word you have to enter. This is the same controller that the Z80 system uses (8000-14) so I'm guessing someone must have run into this before. I'm going to paw through the diagnostic binary to see if there is something that looks magical. Sound familiar?

7 years, 5 months

FP11-C Engineering Drawings?

by jnc＠mercury.lcs.mit.edu

> From: Al Kossow > i'll see about getting CHM's set scanned Oooh, great; thanks very much, _much_ appreciated! Noel

7 years, 5 months

FP11-C Engineering Drawings?

by jnc＠mercury.lcs.mit.edu

Is there a set of FP11-C Engineering Drawings online anywhere? Our favourite search engine didn't turn one up, and according to Manx: http://manx-docs.org/details.php/1,9306 there are none online. Noel

7 years, 5 months

Searching for a lost Macintosh TV (Texas)

by tothwolf＠concentric.net

I'm not really active in any of the classic computing communities apart >from classiccmp, so I would appreciate it if others could pass this message around and see if this computer ended up in the hands of a fellow collector. A good friend of mine who lived in Spring, TX (north of Houston) owned a black Macintosh TV (1993 vintage). During a move many years ago (late 2010), it mistakenly ended up turned in as ewaste. I only found out late this year (2016) that this had happened. Given how rare/uncommon these machines are, chances are very high that it ended up resold on eBay or similar instead of being scrapped. I have no records of the serial number of the machine, but according to my archives, I installed Mac OS 7.6.1 on it on May 5, 1998. It was also upgraded with an 8MB SIMM but still had the factory hard drive. If by some chance a fellow collector ended up with it, and if it still has its hard drive and files intact, my friend would really like to obtain a copy of her files (a disk image of the hard drive would be ideal). I happened to still have a backup of the machine on a zip disk from May 24, 1998, but she had continued to use the machine off and on for many years after that. I would also just like to know that the machine didn't end up scrapped.

7 years, 5 months

Searching for a lost Macintosh TV (Texas)

by ian.finder＠gmail.com

Props for for having a good sense of humor. It made me laugh. Seriously though I hate to say it but your quest feels pretty damn futile. I wish you luck either way, and would offer you my MacTV but it is long gone. If you can provide names of unique files or something that was on the drive- identifiable but not sensitive- it might help you. Like I said, there's nothing to key off of in your original post. I've hunted far rarer specific systems- smbx machines and the like that went missing from universities with good inventory control only one or two years ago- and had zero luck. Also do try Low End Mac and 68kmla, this is more relevant to those audiences. Cheers, - I On Monday, December 5, 2016, Tothwolf <tothwolf at concentric.net <javascript:_e(%7B%7D,'cvml','tothwolf at concentric.net');>> wrote: > On Mon, 5 Dec 2016, Ian Finder wrote: > > They sold 10,000 Apple TVs. That's a lot. >> >> You lost track of one ten years ago, and have given no real methodology >> for discerning it from any other- the number out there with OS 7.6 or 8mb >> of ram will be significant. >> >> Perhaps you should go door-to-door, or hang flyers. It would probably >> yield better results. >> > > [Sorry Jay, but I'm going to do this on-list.] > > Wow, Ian, you sure are helpful! Would you be willing to help me print up > and distribute those fliers? > > <insert giant ascii finger> > > :) > -- Ian Finder (206) 395-MIPS ian.finder at gmail.com <javascript:_e(%7B%7D,'cvml','ian.finder at gmail.com');> -- Ian Finder (206) 395-MIPS ian.finder at gmail.com

7 years, 5 months

Troubleshooting spooky & intermittent instability after power-up: Symbolics XL1200

by ian.finder＠gmail.com

Hi folks, I know this is a long shot but... I'm having a rather curious issue with one of my Symbolics XL 1200 CPUs, which I suspect may have a far more general cause. I have narrowed the issue down to the specific Merlin II CPU card I'm running- not the RAM, Jumper, I/O, backplane, power supply or any of that good stuff. My friend Doug has a rather pretty picture of the board in question on his site: https://symbolics.lisp.engineer/koken/albums/merlin-ii/content/img-4316/lig… It's basically a big wedge of PGA ASIC encapsulations and PALs, for those unfamiliar. The symptom is this. After a cold boot- a fresh power-up from no power applied- the system will hang after 30-40 seconds into the startup with a hard lock and sometimes memory bus issues. If I wait 10 more seconds or so, and hit reset, the system usually comes up fine for hours. If I hold the system in reset for a few minutes during the cold boot before proceeding, the system works fine. The repro rate is close to 100%. If the machine is off for a few minutes, then cold booted, the issue repros. It sounds as if something has gone thermally sensitive in a very deterministic manner. Can that happen with the tantalum caps on the board? Perhaps they are shorting intermittently for the first few dozen seconds? Again, the rest of the system is good- the issue follows this board and only this board no matter which chassis it runs in. All socketed ICs have been reseated. I know this isn't much to go off of, but anyone out there have experience with spooky "intermittent" yet 100% repro-able cold-power-up issues? I'll debug further of course, but thought I'd ask here. Thanks, - Ian -- Ian Finder (206) 395-MIPS ian.finder at gmail.com

7 years, 5 months

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test-drb December 2016