2.4 KiB
2.4 KiB
PROCESSES
uid -1 is superuser
process 1 is "init", runs as superuser
there are ten process slots, pids are 18 bits.
DISK
RB09: Burroughs fixed head disk (same hardware as RD10!)
64 word sectors; 80 sectors/track; 100 tracks/surface; 2 surfaces
8000 sectors/surface
one surface reserved for backup
512,000 words per surface: 1,024,000 characters!!!
first disk block is copy of "system data"
contains time, free block information, process (user) list?!!
first words points to the first block in the free list
free block format
Each block in the free list contains words 1 to 9 which are free block
numbers if positive, or zero for empty positions. Word 0 in the block
points at the next block in the free list, or zero if there is no next
block.
inode format
12 word inodes (5 per block)
710 sectors of inodes (max 3550 files)
i.flags
400000 in use
200000 large file
000040 special file
000020 directory
000017 can be changed by chmod.
10 owner read
04 owner write
02 world read
01 world write
i.dskps 7 block numbers (all indirect blocks if "large file")
i.uid owner
i.nlks link count (negative i.e. -1, -2, -3 -4 etc.)
i.size size (in words)
i.uniq unique value assigned at creation
directory node (dnode) format
d.i i-number of file or zero if an empty entry
d.name four words, space padded
d.uniq i.uniq value of file
two unused words, so 8 words/entry, 8 entries/block
directory files can (only) be truncated by superuser
i numbers
1 core file?? (written by "sys save" or bad system call)
3 "system" default process cdir, must contain "init", "sh"
4 "dd" directory that contains system and user dirs
All dirs must have a link back to dd
6 "ttyin" special file
7 "keyboard" (graphic-2) special file
8 "pptin"?? (paper tape reader) special file
10 "ttyout" special file
11 "display" (graphic-2) special file
12 "pptout" (paper tape punch) special file
swapping
Only one process is in memory at any time (in the high half of the 8KW memory). The ten processes are swapped to the last ten tracks of the disk.