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--- systems:4th_edition [2023/06/01 05:47] – Add changelog segaloco
+++ systems:4th_edition [2023/10/18 17:35] (current) – segaloco
@@ Line 17: / Line 17: @@
 The Fourth Edition marks the first edition of research UNIX for which the accompanying manual is produced in NROFF rather than ROFF.  Many deprecated/retired pages can be found in the manx folder that still bear ROFF formatting.
-Changes include:
+Among the more noticeable changes are:
-  * Epoch is redefined as seconds from 1/1/1970 instead of ms from 1/1/1972
+  * The filesystem has been altered to support 14 character file names (over the previous 8 characters), to support group IDs, and to support indirect blocks allowing the use of larger storage devices (e.g. RP-11 disks)
-  * Addition of the signal(II) syscall, deprecating cemt, fpe, ilgins, intr, and quit syscalls for specific signals
+  * The object file loader has dropped support for V1-style a.out binaries but now supports shared text segments, and associated development tools have been modified to support this as well
+  * The epoch is redefined in seconds instead of milliseconds and with a reference date of 1/1/1970, starting the modern UNIX epoch
+  * The signal(II) system call is added to replace individual system calls for redirecting specific exceptions
+  * The contents of the /sys filesystem have been merged with the /usr filesystem
+  * Pipes have gained their familiar | syntax (along with ^), replacing the > which could be confused with output redirection
+  * Block devices now present both buffered and raw interfaces
+  * The init process now offloads machine-specific startup to /etc/rc rather than requiring modification for different disks and other localisms
+Other changes include:
   * Alteration of makdir(II) into the mknod(II) syscall
   * Removal of the mdate(II) and rele(II) syscalls
@@ Line 29: / Line 37: @@
   * kill(II) can now be used to send arbitrary signals, not just kill itself
   * stat(II) now reports if a file is a block or character special file
-  * exec(II) drops support for V1 a.out files
   * Deprecation of applications targeting the assembly version of UNIX such as tmg(VI) and m6(VI)
@@ Line 41: / Line 48: @@
   * date(I) adds support for setting the year
   * Core files now include the per-process data at the front, not the back
-  * Adds support for shared text segments
   * login(I) now always prompts for a password as opposed to receiving it as an argument
-  * Manpages have been moved from /sys/man to /usr/man
-  * Sources have been moved from /sys/sys to /usr/sys
-  * Supports using | or ^ as pipe instead of >
   * The tty driver supports 12 terminals instead of 10
   * the tty driver now discards the entire buffer on overflow instead of printing '#' per overflow character
   * The tty driver maps uppercase to lowercase if only uppercase is used
   * The console driver now has greater parity with other tty drivers
-  * Block devices now present a raw interface and buffered access
-  * Filesystem filenames (as opposed to ar(I) filenames) are extended to 14 characters
-  * Filesystem objects (as opposed to ar(I) objects) now support group bits
-  * In both above cases, ar(I) is *not* updated to support these
-  * Indirect blocks are added to support larger filesystems (e.g. RP disks)
   * 2741 terminal support appears to be on the way out
-  * The init system now utilizes /etc/rc for operations such as mounting disks (rather than filesystems being hard-coded into init)
   * A new boot procedure is provided for the C UNIX system