[TUHS] Re: Research UNIX PDP 11/45

The most useful thing is probably this: https://minnie.tuhs.org/cgi-bin/utree.pl?file=V4/nsys/ken/low.s which lists exactly what was there; not only the types, but how many of each there are. This is from 'nsys', which is slightly before the actual V4, so it's quite early. 'low.s' is inherently machine-specific; i.e. different machines would share most kernel files identically, but _not_ this one - unless they had _absolutely identical_ device sets. So this one is _probably_ the one from the /45 in picture. It shows: RK11 RF11 PC11 TC11 TM11 1xKL11 12xDC11 1xDP11 (synchronous serial) 1xDN11 (dial-out asynch control) 1xDR11C (parallel port to -11/20) 2xDC11 (Screw Works voice synthesizer) 1xDR11A (voice response unit) 1xDR11C (C/A/T typesetter) (Line printer, card reader and RP11 are commented out; more about the RP11 in a later message. There's also this: https://minnie.tuhs.org/cgi-bin/utree.pl?file=V4/nsys/ken/11-45 which is a bit hard to interpret, but I think might list what's in each rack: the TC11, RK11 (early ones), RF11 and TM11 (early ones) were large custom wire-wrapped backplanes which bolted into the front or back of a 19 inch rack; this: https://gunkies.org/wiki/RK11-C_disk_controller has an image of such an RK11. The "MOS 16-24" is probably a reference to an MS11: https://gunkies.org/wiki/MS11_Semiconductor_Memory_System which had to mount in the CPU backplane. The "MM" entries are likely core memory units; probably MM11-K's: https://gunkies.org/wiki/MM11-K_core_memory since they seem to be 4KW each. (Maybe MM11-E's or 'F's, though; those are also 4KW each.) I'm not sure what they "PL"s are - probably Plessey core? Anyway,it looks like the machine had 104KB total. This file: https://minnie.tuhs.org/cgi-bin/utree.pl?file=V4/nsys/ken/conf.c lists all the types of devices on the machine. One oddity is that it lists two RK11's; but if you look at the RK11 driver: https://minnie.tuhs.org/cgi-bin/utree.pl?file=V4/nsys/dmr/rk.c it's only set up to handle one physical controller. But there is this: #define JRK 1 /* temp */ if (bp->b_dev.d_major==JRK) d = bp->b_dev.d_minor; else d = bp->b_blkno%3; so the two different major device entries appear to handle the same disks in different ways ("d = bp->b_blkno%3" will spread a virtual drive across three physical drives). Memory, it would have been hard to say (UNIX even then sized memory at start up) but then I found that '11-45' file. I also found a copy of the CACM version of the UNIX paper: https://people.eecs.berkeley.edu/~brewer/cs262/unix.pdf which says the machine had 144KB (so they had added 40KB more at that point). (I seem to recall someone had scanned the SOSP version; I didn't save the pointer, but if someone knows where it is, it would be interesting to look, and see what it says - they seemed to update this paper on a regular basis - the copy included with V6 talks about the -11/70.) The system at that point had "a 1M byte fixed-head disk .. four moving-head disk drives which each provide 2.5M bytes on removable disk cartridges, and a single moving-head disk drive which uses removable 40M byte disk packs" The RS11 disks for the RF11 were 512KB, so either they'd added a second one, or switched to an RS04 (but that's a MASSBUS device). The big disk was an RP03 so they had added an RP11, which wasn't present earlier. Noel