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DEC KA650 VAX memory troubleshooting (video)

by joezatarski＠gmail.com

Hey Everyone, I just thought I'd share a video of how I'm going about troubleshooting the bad DRAMs on my MS650 memory board. https://youtu.be/eDMhdAEFEgc I apologize for the shaky-cam, I don't have a tripod, and I needed to do a lot of panning anyway. I will be sharing my notes on the MS650 once I have a chance to write them up properly as well. I wasn't able to find a printset for the RAM card itself, so I assume one doesn't exist in digital form yet. I have documented what bit and memory range each DRAM on the card corresponds to, which may help someone troubleshooting in the future Regards, Joe Zatarski

6 years, 6 months

Who changed the gravitational constant (Dec pdp11 stuff)

by jnc＠mercury.lcs.mit.edu

> From: Chris Zach > The MSV11-QC board ... failed startup diagnostics with what looks like > a stuck bit. .. now I need engineering schematics for that board so I > can replace one of the 41256 memory chips. On the positive side it looks like > a pretty obvious stuck bit, just need to know which chip is at that > address and memory location.... I suspect you're out of luck on the prints, I think all there is is the User Manual. Not to worry, it should be pretty easy to create a bit->chip table, I did that for the MSV11-J: https://gunkies.org/wiki/MSV11-J_QBUS_memory#Technical_information when I needed to repair one; it should be pretty easy to duplicate the process for the -Q. I did it with a 2-instruction scope loop, doing a word write to a given location, floating a '1' bit along a word of '0's, looking at the 'data in' pin on the DRAM chips. I see the -Q has a 17x8 array of DRAMs, so 16 bits of data and a parity bit (odd chip out); so in some ways even easier than the -J (which had ECC). 8 banks, but with a little luck they're in some sort of logical order. I have a -QA, of the later etch rev, which is the same etch as your -QC; so I can help with the mapping process, if you need it; let me know. Noel

6 years, 6 months

UniBone: Linux-to-DEC-UNIBUS-bridge, year #1

by jnc＠mercury.lcs.mit.edu

> From: Rob Doyle > http://www.bitsavers.org/pdf/dec/unibus/RH11-C_Engineering_Drawings.pdf Oooh, thanks ever so much. Not sure how I missed that when I looked on BitSavers for RH11 stuff! Very illuminating - eventually! The M7294-YA seems to be a manual ECO to the M7294; there's a detailed rework list on page 6 of the PDF. I'm still trying to work out what the changes do. E66 is a 'component carrier' header, so it seems like in part the ECO adds a bunch of option-controlling jumpers there (see pg. 2 for a table of what they do). The main thing, though, seems to be the addition of E22, a 74191 binary up/down counter, on page DBCA (pg 10 of the PDF). It seems to modify the operation of 'Bus Hog' mode - maybe to do 16-cycle bursts? (All the bit inputs and outputs are unused; only the Max/Min output - pin 12 - is connected to anything.) That would make sense; with UNIBUS A and B tied together, the original Bus Hog (below) would lock out the CPU from the RH11 until the end of the transfer. Actually, though, even without the cross-connect, having the RH11 going flat out Bus Hog might lock out the CPU from the _KS10 memory_... > However there is plenty of DEC documentation that mentions that the > RH11C has a "bus hog" mode for the KS10 disks so that the Unibus can do > back-to-back 18-bit transactions. The RH11-AB has Bus Hog too; see Section 4.12.10, "BUS HOG Mode", pg. 4-22 (59 of the PDF) in "RH11-AB Option Description" for details; it "hold[s] the Unibus ... until the required number of words have been transferred". Noel

6 years, 6 months

UniBone: Linux-to-DEC-UNIBUS-bridge, year #1

by jnc＠mercury.lcs.mit.edu

> From: Rob Doyle > Your memory is correct. The RH11C was the buffered version of the RH11 Umm, both the -AB and -B have FIFOs - confirmed from the prints. (I have an M7294 if we want to confirm that the prints aren't confused.) Now, maybe the -C has a _bigger_ FIFO (e.g. large enough to hold a complete sector), I could definitely see that. What's your source - I'd like to study/cite it? The only KS10 prints I can find don't show the RP11-C? Noel

6 years, 6 months

UniBone: Linux-to-DEC-UNIBUS-bridge, year #1

by j_hoppe＠t-online.de

>>>> *What it is:* >>>> In case you forgot: UniBone is a plugin board to DEC PDP-11 UNIBUS >>>> systems containing a BeagleBone Black. >>>> >>>> See http://retrocmp.com/projects/unibone. > > Is it possible to get it as a "kit+" where the SMD components only are already soldered onto > the bare board, but all the rest left for those who are ok with a normal soldering iron but > not confident on doing the SMD? Yes, can do that. Joerg

6 years, 6 months

UniBone: Linux-to-DEC-UNIBUS-bridge, year #1

by jnc＠mercury.lcs.mit.edu

> Although, with the 3 SPC slots - although they are on UNIBUS A, and only > UNIBUS B has the 18-bit capability Duhhhh. My brain finally turned on. It is of course perfectly possible to run UNIBUS _A_ (where the SPC slots are) in 18-bit mode too - although the _RH11_ can't use it that way. But you won't be using the RH11 anyway, so who cares? Also, I took another look at the KS10 tech manual, and they do in fact use use an M9200 'thin' jumper (although it's mis-labelled "M9300" in the diagram - that diagram has a number of errors, including the "M8014" in the UNIBUS 'A' In slot - they must mean an M9014 [UNIBUS to 3 flat cables] instead) to link the two UNIBI together. Which answers the question of how the KS10 CPU gained access to UNIBUS A (where the device registers, interrupts, etc are) when it also had to be connected to UNIBUS B (for 18-bit data transfers). So I think all our questions are answerered (except for the -AB/-C difference issue). Noel

6 years, 6 months

TurboDOS for S-100, IMS or L/F Technologies

by new_castle_j＠yahoo.com

I'm restoring an IMS - L/F Technologies S-100 Bus computer.? I've got all the pieces except for the Operating System.? I'm hoping that someone here may have a disk stashed away.? From the literature I have read, I would need TurboDOS version 1.40a or 1.41c from IMS or L/F Technologies.? I've seen TurboDOS 1.3 versions out in the wild from IMS, but the 1.4 version was greatly enhanced and offered better compatibility with my specific hardware.? I'd be much obliged if anyone can help. Thanks, Jonathan new_castle_j at yahoo

6 years, 6 months

UniBone: Linux-to-DEC-UNIBUS-bridge, year #1

by jnc＠mercury.lcs.mit.edu

> the Revision J prints (September 1993). Ooops, typo: '1973'. Noel

6 years, 6 months

UniBone: Linux-to-DEC-UNIBUS-bridge, year #1

by jnc＠mercury.lcs.mit.edu

> From: Eric Smith > One version of the RH11 added a small FIFO (called a "silo" by DEC, > IIRC) in the data path. I don't recall which suffix that was, nor > whether it was the version used in the KS10. Well, the -AB has the FIFO, according to the Revision J prints (September 1993). It's on the M7294 card (see drawings DBCC/D). Interestingly, I have prints for an RH11-B! That appears to differ by having an M7295-YA; that differs from the M7295 by having a hand ECO (i.e. same etch), part of which can been seen in the lower left corner of drawing BCTB - the two one-shots. As to the RH11-C, I looked, and we do have the KS10 prints (MP00540, mis-labelled "KS10_MaintSch" :-), and it does include RH11 prints. Alas, those show an M7294, not the claimed M9294-YA. :-( The RH11 sheets are also out of order (some are at the very back of the pack), and DBCD seems to be missing entirely. They are revision "L", and the RH11-BA prints are revision "H", FWLTW. Noel

6 years, 6 months

UniBone: Linux-to-DEC-UNIBUS-bridge, year #1

by jnc＠mercury.lcs.mit.edu

> From: J?rg Hoppe > UniBone can be used in UNIBUS-A SPC slots in 18 bit mode without any > extra adapters? And can emulate an RH11-C there As far as I can see, yes. > even if the RH11 is supposed to run in UNIBUS B? Well, all RH11's have both UNIBUS A and UNIBUS B; under program control, one can select either A or B to be the one where the DMA from the RH11 happens. (Access to the registers in the RH11 is only possible via UNIBUS A, and interrupts from it can only happen on A.) I'm not sure exactly what your question is, but I hope that answers it! :-) > We've seen early SPC slots (PDP-11/40, '45) without NPG wired, > 'cause SPC was apparently originally meant for "Small" peripherals > without DMA. Is KS10 UNIBUS-A wired to be DMA capable? Good question! Well, the RH11 is designed so that it can other devices 'downstream' from it, on both UNIBI. So that says that NPG is sent _through_ the RH11 on both UNIBI - but doesn't speak to the SPC slots. For that, one needs to look at the backplane wire list - which isn't in the drawings! :-( However, I happen to have an RH11-AB backplane, and it has the AA1-AB2 jumpers for NPG on those three slots. Same thing for interrupts - both UNIBI are wired to for them (although the grant lines for UNIBUS B don't go into the RH11 cards, they are only on the RH11 backplane). Noel

6 years, 6 months

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