test-drb July 2018

test-drb@ccmp.vtda.org

148 participants
163 discussions

how good is the data reliability with CD ROM and DVD RAM?

by dmonnens＠gmail.com

> > I have a lot of backup here stored in CDs, and I have recently bought > an SCSI DVDRAM unit to create new backups in caddies DVD-RAMs (of > 4.2Gbyte each) what is your experience? I recently disposed of a couple hundred DVD and CD backups I'd made. As mentioned in a previous comment, it's simply too impractical to store terabytes of information in 4.7GB segments, plus they take up a LOT of space. HDDs aren't the most reliable, but this is what I use now for that reason. I make sure to keep the previous backup in case something happens. I'll only use optical backups now with the most important data. Backblaze has some interesting stats regarding HDD reliability (they are a data center using thousands of drives running constantly): https://www.backblaze.com/blog/hard-drive-stats-for-q1-2018/ As noted previously, beyond storage conditions, disc longevity depends on the types of dyes used in the discs. Gold is supposed to be best. Early on, they experimented with a wide variety of dye types, and the silver dyes were least reliable, oxidizing in only about 10 years. The thing is, no media format is going to last forever. The only really reliable way of keeping data around is multiple backups and data migration. Basically, for your really important stuff, you'll want a couple of backups, stored in different geographical locations (one local, one on cloud works, too). You'll want to periodically refresh the backups by migrating the data onto fresh media. In the preservation business, the ideal is to refresh after the cost of storage media is 1/2 of the initial investment. So, if you paid $1 a GB for the initial storage media, you'll want to migrate once the new format is $0.50 a GB, and then again when it is $0.25 and so on. This way, the total cost is double what you initially invested. Of course, while the cost per GB might drop steadily, the total amount on a particular media format will increase as well, such that the $150 HDD you bought 5 years ago will have twice the storage for...$150. Definitely open to other suggestions.

5 years, 9 months

DEC uNotes

by jnc＠mercury.lcs.mit.edu

> #30 "PMI on KDJ11-B and MSV11-J" So it turns out there are _two_ uNote sets, with overlapping numbers! (A fact about which I was previously unaware!) I have two PDF files of the collections; micronoteReprints.pdf (the first set), and oemMicronotes.pdf (the second). Note! There's an index to the first set at the back of the second, and it lists 111; but the ToC for the first one only lists 85! But they are in fact all there (and more; the ones there go up through 115). Noel

5 years, 9 months

PDP-11/84 Qbus slots for memory

by jnc＠mercury.lcs.mit.edu

> From: Charles Dickman > an 11/84 with the UNIBUS adapter and PMI memory does not have a Qbus. > ... the KDJ11-B (M8190) bus protocols change when a KTJ11 (UNIBUS > adapter) is present and so what would be expected to be Qbus isn't. Ah, excellent point. Looking at the description of the CPU/UBA adapter in the KDJ11-B User Manual (EK-KDJ1B-UG-001, pp. 7-6 to 7-9), the answer is not certain; it all depends on implementation details on the CPU card which aren't described. E.g. the DMA cycle _might_ work, it all depends on what happens at step 8 when, instead of PBSY being asserted, BSYNC is asserted. The _memory_ will be fine (since in an -11/83, this kind of thing is expected)... but the _CPU_, who knows. Interrupt cycles are more problematic; the assertion of the interrupt level on the BDAL lines (step 1a) will probably pass, but step 6 (assertion of BSACK) may be an issue, since the device will want to assert BRPLY instead (BSACK is not used in a QBUS interrupt), and the CPU may not do the right thing. > I think there was a DEC Micronote that explained the protocol > modifications involved. I don't think so; #30 "PMI on KDJ11-B and MSV11-J" describes the _basic_ PMI, but the interaction with the UBA isn't described there. But the KDJ11-B User Manual has it in some detail. Noel

5 years, 9 months

ps/2 Keyboard with 3 button trackball

by carlojpisani＠gmail.com

hi I am looking for a ps/2 keyboard with a 3 buttons trackball I am currently using a Cherry's kb, but it has a built-in 2 buttons trackball and the software I need to use requires the third button to select items what do you suggest, guys?

5 years, 9 months

CoCo OS/9 was: TRS-80 floppy

by chd＠chdickman.com

So what does it take to get OS/9 running on a Radio Shack Color Computer? I have a Color Computer 2 (? 64k and non-chicklet keyboard) and have always wanted to get it working with a disk OS. What do I need? I see a reproduction floppy disk controller on ebay. I would rather skip that and go straight to some kind of sold state memory. Suggestions or pointer to active groups? On Sun, Jul 22, 2018 at 5:31 PM, W2HX via cctalk <cctalk at classiccmp.org> wrote: > Not mine, just thought it might interest some here > https://www.ebay.com/itm/202376723756 -chuck

5 years, 9 months

Strange third party board in PDP-11/45

by jnc＠mercury.lcs.mit.edu

> We're actually pretty well off, there; we have: > - MS11 Maintenance Manual (DEC-11-HMSAA-D-D) > - MS11 MOS Memory Troubleshooting Guide (DEC-11-HMSTS-A-D) > - MS11-B Engineering Drawings There's also a little bit about the MS11-C (not covered in the documents above) in EK-11045-MM-007. There is a later rev of the MS11 manuals, which does cover the MS11-C; Chuck McManis had both of them: EK-MS11A-MM-006 MS11-A,B,C memory systems maintenance manual EK-MS11A-OP-001 MS11-A,B,C memory systems users's manual but when I contacted him about them a while back, he wasn't sure if he still had them, or if he'd given them to Al K to scan and put up (he was on the road at the time, so couldn't check if he still had them). Al, are they in your queue somewhere? (No rush to do them, if so; I just want to make sure we know where they are.) > If the board is a cache, how does it get filled? It would have to listen > to the UNIBUS the memory is on. ... Note that there has to be a signal > from FastBus ... which tells the CPU if the MS11 has a given address or > not ... so the cache board could use that line to tell the CPU whether > or not the location in question is in the cache. Studying the MS11 Maint Manual, the MS11 controller has access to the full address and data from both the CPU (FastBus) and UNIBUS B. (The FastBus actually has two uni-directional data busses; in and out.) So all that info, this hypothetical cache board can get from the slot it is plugged into (assuming the cache is plugged into one of the controller slots), over its connector pins. The connectors on the back of the card, and two small boards, must be for listening to UNIBUS A (in configurations in which the two UNIBI aren't joined together)? (I'm too lazy to check the slot numbers are see what they actually are.) And there is indeed a signal which the MS11 uses to tell the CPU it has the location the CPU is asking for, so it's theoretically possible to build a cache card that plugs into a FastBus slot. Noel

5 years, 9 months

PDP-11/84 Qbus slots for memory

by mark＠matlockfamily.com

The PDP-11/84 uses the M8190 CPU that is also used in a PDP-11/83. The 11/83 and 11/84 use PMI Memory but the 11/83 also can use Q22 memory. With the 11/83 the position of the memory board (assuming one is using the MSV11-JD or JE) above the CPU uses PMI and below the CPU in the backplane uses Q22. In the 11/84 the CPU is above the MSV11-JE memory but the CPU only uses PMI to talk to memory. diagrams in the Unibus processor handbook indicate that the M8191 Unibus map board only communicates through the PMI bus to both memory and to the CPU. Now my question is, there are 3 Bus slots in the 11/84 above the Unibus map board, would it be possible to put a dual width Q22 I/O board in the second memory slot (not the PMI side of the slot) and have it able to DMA into the MSV11-JE? If so then something like an Emulex UC07 and a SCSI2SD card could make a cost effective disk solution, since Unibus SCSI controllers are so expensive. Mark

5 years, 9 months

Semi-OT: Hitachi Seiki Micon16-II

by jplist2008＠kiwigeek.com

Good arvo all; A family member recently purchased a rather large CNC which uses a Micon16-II system (as well as a Fanuc 15M) to drive it. Unfortunately the battery for the RAM died during storage prior to him getting it and all of the ladder logic is gone. We'd really love to try and find some kind of technical manual for the 16-II, or anything really, to assist in talking with the machine and interrogating it's state. We have a copy of the missing ladder logic in paper form so we're not totally out of luck, but the ability to enter it in segments rather in one 40 hour slog might be nice. If anyone has anything easily sharable we'd very much appreciate the assistance; Thank you. - JP

5 years, 9 months

Saturn V program punch card decks

by BHuntsman＠mail2.cu-portland.edu

Anyone see this? https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.com%2Fulk%2F… Hopefully the new owner will read it in and make the contents available. Looks like a fascinating piece of history! Pushing a tad rich for my blood though given that I don?t have a card reader

5 years, 9 months

MOS MCS2529 math chip

by jules.richardson99＠gmail.com

Anyone got pinout/spec information for a MOS MCS2529? In particular, I'm curious about operating voltage. I acquired a Melcor SC-635 calculator yesterday and there seems to be some uncertainty about the output voltage of its (rechargeable) battery pack; some places say 2.4V, i.e. the pack is a pair of 1.2V cells, but others say 9V. 2.4V seems a little low to me for typical logic, but on the other hand I've seen a period ad which says that the external PSU was 9V - and so the rechargeable battery must have been somewhat less than that. cheers Jules

5 years, 9 months

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test-drb July 2018