From 858fe3dd13d607e04425b7e855905f398e0ee0aa Mon Sep 17 00:00:00 2001 From: Phil Budne Date: Tue, 8 Mar 2016 12:10:31 -0500 Subject: [PATCH] notes on kernel & disk format --- src/sys/NOTES.md | 63 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 63 insertions(+) create mode 100644 src/sys/NOTES.md diff --git a/src/sys/NOTES.md b/src/sys/NOTES.md new file mode 100644 index 0000000..bc8ff11 --- /dev/null +++ b/src/sys/NOTES.md @@ -0,0 +1,63 @@ +PROCESSES +========= + +uid -1 is superuser + +process 1 is "init", runs as superuser + +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?!! + +12 word inodes (5 per block) +710 sectors of inodes (max 3550 files) + +inode format +------------ + i.flags + 400000 free?? (checked/toggled by icreat) + 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 + i.size size (in words?) + i.uniq unique value assigned at creation + +directory files can (only) be truncated by superuser + +directory node (dnode) format +----------------------------- + d.i i-number of file + d.name four words, space padded + d.uniq i.uniq value of file + +i numbers +--------- + + 1 core file?? (written by "sys save" or bad system call) + 2 "dd"??? "root" directory + 3 "system"??? default process cdir, must contain "init", "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