Build ARCDEV.

Makefile

@@ -1,5 +1,5 @@
 SRC = system syseng sysen1 sysen2 sysnet kshack midas _teco_ rms klh
-MINSYS = _ sys sys3
+MINSYS = _ sys sys3 device
 RAM = bin/boot/ram.262
 NSALV = bin/boot/salv.rp06
 DSKDMP = bin/boot/dskdmp.rp06

README.md

@@ -40,5 +40,6 @@ from scratch.
    - ATSIGN DEVICE, load device drivers.
    - TCTYP and CRTSTY, terminal handling.
    - PEEK, system monitoring.
+   - ARCDEV, transparent file system access to archive files.
 
 4. Finally, the whole file system is dumped to tape.

build/build.tcl

@@ -172,6 +172,10 @@ respond "*" "purify\033g"
 respond "Idle" "q"
 expect ":KILL"
 
+respond "*" ":midas device;jobdev arc_syseng;arcdev\r"
+expect ":KILL"
+respond "*" ":link device;jobdev ar,device;jobdev arc\r"
+
 respond "*" "\005"
 respond "sim>" "at tu0 out/output.tape\r"
 respond "sim>" "c\r"

doc/sysdoc/arcdev.format

@@ -0,0 +1,84 @@
+;Archive device format:
+
+;The first page of an archive device file is its directory.
+;The remaining pages are data.
+
+;The directory may not even be looked at unless the archive is "locked".
+.SEE LOCK,UNLOCK	;Only one ARCDEV can lock a given archive at a time.
+;Shuffling the directory should not be done in place, even when it is locked.
+;Instead, use DIRGET to make a copy and DIRPUT to store the copy back in.
+;When a file is open, the address of its data area is remembered in FILADR.
+;The data area of a file never moves, and the file can be open only in one
+;direction at a time, so reading or writing the data area requires no interlocking.
+
+;The format of the archive device directory is approximately that of
+;an I.T.S. UFD.  The differences are:
+
+;In the fixed header, word 0 (UDESCP) contains SIXBIT /ARC1!!/
+;Word 1 points to the beginning of the name area, as in UFDs.
+;Word 2 points to the end of the data area.
+;Word 3 is used to tell when the archive needs to be cleaned
+;  because it is being touched for the first time since the system came up.
+;Word 4 contains what is supposed to be the creation date of the archive.
+;  Since locking the archive device clobbers the creation date,
+;  we store it here so we can restore it after clobbering it.
+;Word 5 similarly stores the dumped bit.
+
+;There is nothing analogous to the "descriptors" in a disk UFD.
+
+		;Random info in UFD
+UDESCP==0	;SIXBIT /ARC1!!/
+UDNAMP==1	;Address in directory of first filename block.
+UDDATP==2	;Address of first free word past data area of last file.
+UDINIT==3	;Time of startup of last run of system during which this
+		;archive was cleaned (ARCCLN).  If not same as startup time
+		;of this run of the system, we must do ARCCLN.
+UDCRDT==4	;This word holds what ought to be the creation date
+		;of the archive device file itself.
+		;0 => this archive antedates the UDCRDT word, in which
+		;case it gets set from today's date.
+UDDMPB==5	;This is like UDCRDT but stores the dumped bit.
+
+UDNMIN==10	;If UDNAMP is less than this, there is no room for another filename block.
+
+;In each filename block, the UNFN1, UNFN2, UNDATE and UNREF words are
+;just as in UFDs.  The UNRNDM word is slightly different:
+
+LUNBLK==5	;Number of words in each filename block.
+UNFN1==0	;First file name.
+UNFN2==1	;Second file name.
+UNRNDM==2	;All kinds of random info:
+		;The RH is the address in the file of the start of the file's data area header.
+		;The LH contains these bits:
+	UNWRIT==4		;Open for writing.  Not actually maintained in the archive,
+				;Just reflected to the user when he reads ARC:.FILE. (DIR).
+	UNCDEL==20		;Delete this file when it is closed.
+	UNIGFL==24		;Bits to ignore file
+	UNWRDC==301200,,	;Word count of last block mod 2000.
+				;This information really lives in UHWCNT, and is just reflected
+				;here when the user reads the image directory.
+UNDATE==3	;Date and time file last modified.
+	UNTIM==2200,,		;Compacted time of creation
+	UNYMD==222000,,		;Y,M,D of creation
+	UNMON==270400,,		;Month
+	UNDAY==220500,,		;Day
+	UNYRB==330700,,		;Year
+UNREF==4	;Reference date same as left half of undate
+	UNREFD==222000,,	;Reference date byte pointer
+	UNAUTH==111100,,	;MFD index of author, all 1=> no directory.
+	UNBYTE==001100,,	;File byte size and length info.
+		;LET S=BITS PER BYTE, C=COUNT OF UNUSED BYTES IN LAST WD
+		;400+100xS+C	S=1 TO 3	C=0 TO 35.
+		;200+20xS+C	S=4 TO 7	C=0 TO 8
+		;44+4xS+C	S=8 TO 18.	C=0 TO 3
+		;44-S		S=19. TO 36.	C=0
+		;NOTE THAT OLD FILES HAVE UNBYTE=0 => S=36.
+
+
+;The data of a file starts with two words of header information:
+UHWCNT==0	;Total length of the file's data, including header, in words.
+UHREFC==1	;RH: Number of archives using the file, in either direction.
+		;LH: -1 if file open for writing.
+UHNAMP==2	;Unused
+UHBLEN==3	;Length of this header;  offset to 1st actual data word.
+