[HN Gopher] PDP-11/Hack (2014)
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PDP-11/Hack (2014)
Author : dcminter
Score : 88 points
Date : 2023-01-03 08:08 UTC (14 hours ago)
(HTM) web link (madrona.ca)
(TXT) w3m dump (madrona.ca)
| dingosity wrote:
| I especially love how Brent is using (what looks like) a VT220 to
| communicate with the ODT.
| louwrentius wrote:
| Awesome, project, way beyond my skill level.
|
| If you are interested in the PDP-11, A youtuber (Usagi Electric)
| bought a PDP-11/83 and is going to try and get it working again.
|
| https://www.youtube.com/watch?v=SB95dlrS5kU
| JPLeRouzic wrote:
| I have a LSI-11 CPU card (M7264), it even has 4K RAM, I wonder if
| it would be possible to make a similar card with two UARTs for
| its Qbus?
| kjs3 wrote:
| In theory, sure. In practice, it's a little more complicated
| than that. First, it would need to talk to the Q-Bus, which is
| something like "more complicated than the ISA bus, but not as
| complicated as PCI bus". It's at least very well documented and
| lots of people have made their own cards (recently, even).
| There's also the fact that while there are "close but not
| quite" modern replacements, the bus interface chips DEC used
| haven't been made in decades and are hard to find without
| stripping another Q-Bus board (and the ones on eBay are almost
| certainly fake or fried). Probably fine for a 2-card system to
| use modern replacements; gets to be a problem with bigger
| backplanes. Google will get you exhaustive discussions of what
| is and isn't likely to work ("DS8641 qbus" is probably a good
| search term to get started).
|
| Obviously, easier to find one of the DLV11 Q-Bus serial board
| variants.
|
| One other note, there are multiple versions and revisions of
| M7264 boards. You'll want to know exactly which one to know
| what to expect to get it running (e.g. read the doco).
| JPLeRouzic wrote:
| Thanks for your remarks.
|
| > _the bus interface chips DEC used haven 't been made in
| decades and are hard to find_
|
| People seems to use 7438/74LS38 and 74LS02 with some success.
|
| https://forum.vcfed.org/index.php?threads/which-receiver-
| and...
|
| An example could be seen from page 116 in February 1980
| edition of Byte magazine:
|
| https://ia600307.us.archive.org/11/items/byte-
| magazine-1980-...
| kjs3 wrote:
| Like I said, the alternatives can certainly work. Until
| they don't. And some alternatives work better than others.
|
| I checked some notes and found the Eric Smith[1] page where
| I learned about this. Eric has been around the
| retrocomputing and DEC world for a long time.
|
| I also have a note that the Russian KR559IP3 is the
| equivalent to/copy of the original driver chips. I've never
| seen one.
|
| [1] http://www.brouhaha.com/~eric/retrocomputing/dec/interf
| acing...
| ggm wrote:
| I had a ceramic DIP 11/70 but never worked out what to do with
| it. Eventually I gave it away. It was a single chip afaik not
| this dual chip on one carrier.
| kjs3 wrote:
| This is really nifty work, and I wired it up a couple of years
| ago when he published and it worked with one of my DCJ-11s.
| Fooled around in ODT for a whole afternoon. Unfortunately, most
| of the PDP-11 operating systems expect a _lot_ of non-trivial
| system infrastructure in place to boot. I thought about doing
| something in ROM (maybe a Forth?), but moved on to other
| projects.
| ChicagoDave wrote:
| I believe there's a guy that attends the THE VINTAGE COMPUTER
| FESTIVAL MIDWEST that had this working. I saw something like it 2
| years ago.
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