Our campus had an 1108 at the University of Utah Computer Center, but I chose to avoid it, because it was run in batch mode with punched cards, and never got networking.

Clem Cole asks: I was unaware of that compiler until sometime in the 21st Century, long after our PDP-10 was retired on 31-Oct-1990. The site https://github.com/PDP-10/Snyder-C-compiler/tree/master/tops20 supplies a list of some of Snyder's files, but they don't match anything in our TOPS-20 archives of almost 180,000 files. I then looked into our 1980s-vintage pcc source tree and compared it with a snapshot of the current pcc source code taken three weeks ago. The latter has support for these architectures aarch64 hppa m16c mips64 pdp11 sparc64 amd64 i386 m68k nova pdp7 superh arm i86 mips pdp10 powerpc vax and the pdp10 directory contains these files: CVS README code.c local.c local2.c macdefs.h order.c table.c All 5 of those *.c files are present in our TOPS-20 archives. I then grepped those archives for familiar strings: % find . -name '*.[ch]' | sort | \ xargs egrep -n -i 'scj|feldman|johnson|snyder|bell|at[&]t|mit|m.i.t.' ./code.c:8: * Based on Steve Johnson's pdp-11 version ./code2.c:19: * Based on Steve Johnson's pdp-11 version ./cpp.c:1678: stsym("TOPS20"); /* for compatibility with Snyder */ ./local.c:4: * Based on Steve Johnson's pdp-11 version ./local2.c:4: * Based on Steve Johnson's pdp-11 version ./local2.c:209: case 'A': /* emit a label */ ./match.c:2: * match.c - based on Steve Johnson's pdp11 version ./optim.c:318: * Turn 'em into regular PCONV's ./order.c:5: * Based on Steve Johnson's pdp-11 version ./pftn.c:967: * fill out previous word, to permit pointer ./pftn.c:1458: register commflag = 0; /* flag for labelled common declarations */ ./pftn2.c:1011: * fill out previous word, to permit pointer ./pftn2.c:1502: register commflag = 0; /* flag for labelled common declarations */ ./reader.c:632: p2->op = NOASG p2->op; /* this was omitted in 11 & /6 !! */ ./table.c:128: " movei A1,1\nZN", /* ZN = emit branch */ ./xdefs.c:13: * symbol table maintainence Thus, I'm confident that Jay's work was based on Steve Johnson's compiler, rather than Alan Snyder's. Norman Wilson asks: Our pcc compiler treated char* as a pointer to 7-bit ASCII strings, stored in the top 35 bits of a word, with the low-order bit normally zero; a 1-bit there meant that the word contained a 5-digit line number that some compilers and editors would report. Of course, that low-order non-character bit meant that memset(), memcpy(), and memmove() had somewhat dicey semantics, but I no longer recall their specs. kcc later gave us access to the PDP-10's 1- to 36-bit byte instructions. For text processing, 5 x 7b + 1b bits matched the conventions for all other programming languages on the PDP-10. When it came time to implement NFS, and exchange files and data with 32-bit-word machines, we needed the ability to handle files of 4 x 8b + 4b and 9 x 8b (in two 36-bit words), and kcc provided that. The one's-complement 36-bit Univac 1108 machines chose instead to store text in a 4 x 9b format, because that architecture had quarter-word load/store instructions, but not the general variable byte instructions of the PDP-10. Our campus had an 1108 at the University of Utah Computer Center, but I chose to avoid it, because it was run in batch mode with punched cards, and never got networking. By contrast, our TOPS-20, BSD, RSX-11, SunOS, and VMS systems all had interactive serial-line terminals, and there was no punched card support at all. ------------------------------------------------------------------------------- - Nelson H. F. Beebe Tel: +1 801 581 5254 - - University of Utah FAX: +1 801 581 4148 - - Department of Mathematics, 110 LCB Internet e-mail: beebe(a)math.utah.edu - - 155 S 1400 E RM 233 beebe(a)acm.org beebe(a)computer.org - - Salt Lake City, UT 84112-0090, USA URL: http://www.math.utah.edu/~beebe/ - -------------------------------------------------------------------------------

> Anyone know of good description of SAIL computer systems?

Clem Cole asks: > I wonder why Jay did his version? Maybe he wanted more modern C > features since the Snyder compiler would been based on a very early C > dialect.

Besides our PDP-10s, we had several PDP-11s and VAXes that could run Unix, so we wanted our software to run on all of those systems