usb to unibus - was installing 2.11BSD on a pdp11/53

At 02:24 PM 12/20/2013, John Wilson wrote: Yes, there was a version of TSS/8 that ran on RK05 media. The way I implemented this was to use OS/8 on the "RKA0" half of the disk, compiling the TSS/8 bits, and installed TSS/8 on the "RKB0" side. As you mention, TSS/8 is highly dependent upon the RF08's (or DF32's) ability to read/write single words, so those I/O operations have to be buffered. Given an 8/E or later base, it's not hard to find stuff that can be deleted to make room for a buffer to manage that. This definitely had lower performance than a RF08, but this was a hack that never saw real operation. Bob Shelley wrote a UUO for TSS/8 that allowed an application to operate what would be called pseudo terminals today: send input to a detached terminal's input buffer and read whatever was in the terminal's output buffer. With that, I could fire up a system with 24 virtual terminals and run memory tests in all 24. That was a very effective stress test. All of this was during my field service support days at DEC. One example was trying to support a school system that had been promised that they could have 24 terminals running at once on their TSS/8 system. Their 8/E system with expansion box to handle 24 KL8Es, bus converter, 32 Mb of memory, etc. was just too fragile (too many bus loads) and failed all the time. Eventually, DEC replaced the expansion box with an 8A box and KL8A multiport serial controllers. I implemented support for the KL8/A in TSS/8. Sadly, none of that code ever saw the light of day outside of DEC. -Rick