3 ms·

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 4y ago
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 4y ago
  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-driver-ics-for-q-bus.64369/ 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-1980-02/1980_02_BYTE_05-02_Graph_Theory.pdf https://ia600307.us.archive.org/11/items/byte-magazine-1980-...
  - kjs3 4y ago
    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 КР559ИП3 is the equivalent to/copy of the original driver chips. I've never seen one. [1] http://www.brouhaha.com/~eric/retrocomputing/dec/interfacing/chips.html http://www.brouhaha.com/~eric/retrocomputing/dec/interfacing...

kjs3 4y ago

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 4y ago
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-driver-ics-for-q-bus.64369/ 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-1980-02/1980_02_BYTE_05-02_Graph_Theory.pdf https://ia600307.us.archive.org/11/items/byte-magazine-1980-...
- kjs3 4y ago
  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 КР559ИП3 is the equivalent to/copy of the original driver chips. I've never seen one. [1] http://www.brouhaha.com/~eric/retrocomputing/dec/interfacing/chips.html http://www.brouhaha.com/~eric/retrocomputing/dec/interfacing...