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  1. vrs42

    pdp-8/e address won't increment

    Since it seems no part of MA is getting routed to the adder, that suggests to me a problem in the M8310, though I suppose it could be the inverter from pin 5 to pin 6 of E64 in the M8300. I'd probably start with the "MAC" flop at E17 on the M8310. That should set on every rising TP4, which is...
  2. vrs42

    pdp-8/e address won't increment

    Yes, I'd say that somehow the "old value" isn't getting to the adder, so all you ever get is the carry-in (1+0==1). I'm out for the next several hours, but I'll try to make some time to look at the drawings this afternoon. Vince
  3. vrs42

    Bus Loads M8320: Replacement for diode D664

    Most uses of D664 do not seem super critical. Most signal diodes are probably close enough. (Not "in spec" mind you, but good enough.) Your mileage may vary if you are fixing "S" or "B" series modules. (For those, I'd consider a Schottky diode, which will be "off spec" in a direction more...
  4. vrs42

    Looking for dec-08-aj4e-pb

    I think I've got aj1 covered. ... Those are the meta-data. The actual files described there should exist over in pdp8/src/dec/dec-08-aj4, but they don't. Thanks for looking!
  5. vrs42

    Looking for dec-08-aj4e-pb

    I've got some files from Doug which tried to be this tape image, but it seems to be truncated. (There's no trailer.) It should have the REMOVE and REPLAC overlays to remove or replace the FOCAL69 extended functions. Does anyone have the tape image? I see that RICM has a picture of the...
  6. vrs42

    Looking for PDP-8/E Floating Point Packages

    I checked that it builds the original binary, and then added the source file as suggested. I've been finding there are files that I have, but somehow they've not made it to the archive. I wrote a tool to identify such cases (runs for an hour and a half; I have a lot of files), and as a result...
  7. vrs42

    Looking for PDP-8/E Floating Point Packages

    I have verified the dec-08-nfppa and dec-08-nfpea directories on my website: https://so-much-stuff.com/pdp8/software/dec.php https://svn.so-much-stuff.com/svn/trunk/pdp8/src/dec/dec-08-nfppa https://svn.so-much-stuff.com/svn/trunk/pdp8/src/dec/dec-08-nfpea The latter I had to copy in from the...
  8. vrs42

    IOB6120 questions

    You're welcome. Mostly it is Bob and Jim's original stuff collected up, but I also tried to collect the tools and the versions for BTS6120.PLX, the fastest changing part. The stuff that didn't change much, like the flash image and other PLD content you still have to find in the directories...
  9. vrs42

    Plessey PM-837 (Omnibus card)

    I would also look at the USER status light and make sure the M837 clone doesn't think you are in user mode. That's actually a failure mode for the M837 that I've seen before.
  10. vrs42

    IOB6120 questions

    Looks like the date stamp in the v320 binary is "09-APR-10 21:15:39". The date stamp for the v321 binary is "07-MAR-11 14:04:47", so I've added the v320 files.
  11. vrs42

    IOB6120 questions

    As far as I know, all the FLASH.DL images are identical, and all my IOB hardware changes are minor and backward compatible. (By which I mean the stuff that the FPGA cares about.) You'd still need v321 for the SBC6120 firmware to load that flash image into a 29F400.
  12. vrs42

    IOB6120 questions

    Interesting. I was looking for a valid vintage copy of 320[HL].HEX. I had the source code, but not the release binaries. I'll check the dates on those and assuming they are plausible, we may well have the v320 distribution as well. The source appears identical to the v320 that I started...
  13. vrs42

    IOB6120 questions

    OK, I think I have sufficient stuff checked in here: https://svn.so-much-stuff.com/svn/trunk/pdp8/iob6120 to get you to the latest SBC6120 and IOB6120 stuff that I have. I've copied the various tools to the "tools" directory, and made most of them run on Linux. I also tweaked "palx" so that...
  14. vrs42

    Is there any way to look up DEC internal part numbers of the format ##-#####-##?

    The first two PDF referenced here: https://www.so-much-stuff.com/pdp8/repair/subst.php give part the number references for various things, mostly DEC part numbers for replacement parts supplied to DEC by various vendors. I'm not aware of anything that enumerates the part numbers for DEC-built...
  15. vrs42

    IOB6120 questions

    I see that the new code apparently *isn't* in the SVN; only in my Windows 7 backups. I better clean that up and check it in! The 28F400 part is probably a better choice if you can get it. That should work regardless of which firmware is in your SBC6120.
  16. vrs42

    IOB6120 questions

    I still have a big box of IOB6120 stuff downstairs, and the "new" code should still be somewhere in my SVN. Vince
  17. vrs42

    D662/D664 Diode Replacements?

    I was able to find a datasheet that quotes the forward voltage for 1N4153 at 1 mA (typical logic input current) as 0.59V (0.62 for 2 mA). That same sheet quotes 1N914B and 1N916B as 0.72V and 0.73Vat 5 mA...
  18. vrs42

    D662/D664 Diode Replacements?

    I like that idea. Though I'm not sure how authentic to the original design, I have to admit I don't fully grasp what the D664 diode was or what the modern equivalent is. Perhaps it is simplest to think of it as an approximation of a Schottky diode. A clarification of the actual use of the...
  19. vrs42

    D662/D664 Diode Replacements?

    Well, that wouldn't be following the original designs, which was one of my goals. I don't want to redesign the Logic Lab (or other vintage gear); just replace the missing and defective bits. To be functional, I believe a zener based regulator would need the output filtered, as the diode itself...
  20. vrs42

    D662/D664 Diode Replacements?

    It has happened to me a couple of times now. I go to Mouser, and I spend an afternoon staring at data sheets for switching diodes. I'm looking for diodes with low and high forward voltage drops, to replace standard bits of the logic in Bxxx, Rxxx, and Sxxx logic gates. There are almost always...
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