sys comments

src/sys/s1.s

@@ -65,7 +65,7 @@ sysexit:			" common system call exit code
 1:
    dzm .insys			" clear "in system call" flag
    jms chkint			" pending user interrupt?
-      skp			"  no
+      skp			"  no, return to user
    jmp .save			"   yes: dump core
    jms copy; u.rq+2; 10; 6	" restore auto-index locations 10-15
    lac u.rq+1			" restore auto-index location 9
@@ -77,7 +77,7 @@ sysexit:			" common system call exit code
    lac u.ac			" restore AC register
    jmp u.rq+8 i			" return to user
 
-	" scheduler / idle loop
+	" scheduler / swapper / idle loop
 swap: 0
    ion
 1:
@@ -176,8 +176,8 @@ locn:
 	" call:
 	" .insys/ 0
 	"   jms chkint
-	"    no: no interrupt, or intflg set (discards interrupt)
-	"   yes: PI off, .insys set
+	"    <already ".insys", no interrupt, or intflg set (ignore interrupt)>
+	"   <found user interrupt: PI off, .insys set>
 chkint: 0
    lac .insys
    sza				" in system?

src/sys/s2.s

@@ -216,7 +216,7 @@
    sza				" zero (read)
    lac d1			"  no: get write mode bit
    sna				" non-zero (write)?
-   lac d2			"  no: get read mode bot
+   lac d2			"  no: get read mode bit
    dac mode			" save for access call
    lac u.cdir			" get current working directory
    jms namei; 0:0		" search for file

src/sys/s3.s

@@ -330,9 +330,9 @@ rppti:
       jmp .+3
    alss 9
    jmp passone
-   lac sfiles+3
-   sma
-   rsa
+   lac sfiles+3			" get sleep word
+   sma				" high bit set?
+   rsa				"  no: reader select alphanumeric mode
 1:
    jms sleep; sfiles+3
    jms swap

src/sys/s5.s

@@ -248,13 +248,13 @@ dspinit: 0
    jmp dspinit i
 
 	" "move display" (change display buffer pointer)
-	" called with new buffer pointer in AC??
+	" called with new buffer pointer in AC
 movdsp: 0
    iof
-   cdf
-   dac dspbufp
+   cdf				" clear display flags (stop)
+   dac dspbufp			" save display buf pointer
    -1
-   dac .dspb
+   dac .dspb			" .dspb = -1
    ion
    jmp movdsp i
 

src/sys/s7.s

@@ -4,25 +4,25 @@
 pibreak:		" priority interrupt break processing "chain"
    dac .ac		" save interrupt AC
 	"** CROSSED OUT....
-   dpsf
-   jmp 1f		" disable the Graphics-2 I/O
+   dpsf			" skip on data phone flag set
+   jmp 1f		"  not set: check next device
 
-   dpcf
-   dprs
-   dac dpstat
-   sma ral
-   jmp 2f
-   dprc
-   dac dpchar
+   dpcf			" clear dataphone flag
+   dprs			" read dataphone status
+   dac dpstat		" save for user
+   sma ral		" REC FLG set? rotate flags left
+   jmp 2f		"  no
+   dprc			" read char (bit zero set if parity correct)
+   dac dpchar		" save for user
    -1
-   dac dpread
-   lac dpstat
-   ral
+   dac dpread		" dpread = -1
+   lac dpstat		" get status back
+   ral			" rotate up
 2:
-   sma
-   jmp piret
+   sma			" XMIT FLG set?
+   jmp piret		"  no: return from interrupt
    -1
-   dac dpwrite
+   dac dpwrite		" dpwrite = -1
    jmp piret	"** END OF CROSSOUT
 
 1: clsf			" clock overflow (line frequency ticks)?
@@ -40,7 +40,7 @@ pibreak:			" priority interrupt break processing "chain"
 cnop:			" fetched as constant in iread
    nop			
    -1
-   dac 7		" set location 7 to -1 (nothing ever clears it)
+   dac 7		" set location 7 to -1 (nothing ever checks/clears it?)
    clon			" enable clock interrupts, reset flag
    lac ttydelay		" tty delay positive?
    spa			"  yes: skip to skp
@@ -49,16 +49,17 @@ cnop:			" fetched as constant in iread
    jms ttyrestart	"     yes: start output
 	"** START CROSSED OUT: written: lac tty
    lac .dspb
-   sna
-   jmp piret
-   isz .dsptm
-   skp
-   jmp dsprestart
-   sad d3
-   jmp piret
-   isz .dspb
-   jmp piret
-   jmp dsprestart "** END CROSSED OUT
+   sna			" .dspb != 0?
+   jmp piret		"  no: return
+   isz .dsptm		" increment .dsptm; is zero?
+   skp			"  no
+   jmp dsprestart	" yes: restart display
+   sad d3		" .dspb == 3?
+   jmp piret		"  yes: return
+   isz .dspb		" increment .dspb; is zero?
+   jmp piret		"  no: return from interrupt
+   jmp dsprestart	" yes: restart display
+		"** END CROSSED OUT
 
 1: dssf			" disk flag set?
    jmp 1f		"  no
@@ -192,21 +193,21 @@ ttyrestart: 0
    dac sfiles+2
    jmp piret
 
-1: rsf				" paper tape ready?
+1: rsf			" paper tape reader ready?
    jmp 1f		"  no
 
 
 "** 01-s1.pdf page 44
 
    lac npptchar
-   sna
-   jmp .+5
-   dac char
-   rrb
-   dac npptchar
+   sna			" have saved char?
+   jmp .+5		"  no: jump to second rrb
+   dac char		" yes: save as current char
+   rrb			" clear flag, read reader buffer
+   dac npptchar		" save as saved char
    jmp .+3
-   rrb
-   dac char
+   rrb			" here without saved char: read new
+   dac char		" save as current
 3:
    lac char
    sna
@@ -218,16 +219,16 @@ ttyrestart: 0
    sad d4
    jmp 4f
 2:
-   lac npptchar
-   sna
-   jmp .+4
-   dac char
-   dzm npptchar
+   lac npptchar		" get saved char (if any)
+   sna			" had saved char?
+   jmp .+4		"  no: wake up writer
+   dac char		" yes: save as char to send
+   dzm npptchar		" clear saved char
    jmp 3b
-   rsa
+   rsa			" reader select alphanumeric mode
    lac sfiles+3
-   jms wakeup
-   xor o400000
+   jms wakeup		" wake sleepers; returns zero
+   xor o400000		" set high bit (rsa before sleep)
    dac sfiles+3
    jmp piret
 3:
@@ -239,19 +240,19 @@ ttyrestart: 0
    dac sfiles+3
    jmp piret
 
-1: psf					" paper tape ready?
+1: psf			" paper tape punch ready?
    jmp 1f		"  no
 
    pcf			" clear ptp flag
    lac d5
    jms getchar		" get next char
-   jmp .+3
-   psa
-   jmp piret
-   lac sfiles+4
-   jms wakeup
-   dac sfiles+4
-   jmp piret
+   jmp .+3		"  none: wake sleepers
+   psa			" punch set alphanumeric mode
+   jmp piret		" return from interrupt
+   lac sfiles+4		" get sleeper bit vector
+   jms wakeup		" wake them
+   dac sfiles+4		" store zero
+   jmp piret		" return from PI
 
 		"** BEGIN CROSSED OUT
 1: spb			" any graphic-2 push button?
@@ -286,7 +287,7 @@ ttyrestart: 0
 1: crrb			" read card reader buffer??
 
 piret:			" return from priority interrupt
-   lac 0				" get LINK/PC
+   lac 0		" get LINK (in bit 0)
    ral			" restore LINK
    lac .ac		" restore AC
    ion			" reenable interrupts
@@ -327,7 +328,7 @@ wakeup: 0
    jmp wakeup i
 t = t+2
 
-	" call to output CR after LF (NL)
+	" call to output CR after LF (NL) on TTY
 putcr: 0
    lac o15
    dac nttychar

src/sys/s8.s

@@ -117,6 +117,7 @@ dspbuf:
 	" X-Y: invisible, no delay, Y=01740 (992)
 	" X-Y: invisible, settling delay, X=0
    .=.+30
+	" Kernel startup (reused for display buffer)
 coldentry:
    dzm 0100 " not re-entrant
    caf				" clear all flags
@@ -145,14 +146,14 @@ edskbsp: .
 uquant: .=.+1			" number of ticks user has been running
 dspbufp: .=.+1			" pointer to display buffer
 pbsflgs: .=.+2			" buttons on last tick, last button interrupt
-mode: .=.+1
+mode: .=.+1			" user access mode: 1 for write, 2 for read
 nttychar: .=.+1			" CR to send next, or zero
-npptchar: .=.+1
+npptchar: .=.+1			" saved PTR char
 ttydelay: .=.+1			" delay count for TTY output
-name: .=.+4
-lnkaddr: .=.+1
-char: .=.+1
-dskaddr: .=.+1
+name: .=.+4			" file name for current sys call
+lnkaddr: .=.+1			" temp for character queue routines
+char: .=.+1			" current char: temp for PI
+dskaddr: .=.+1			" number of block in dskbuf
 uniqpid: 1			" pid generator
 lu: .=.+4			" user (process) table entry copy
 sfiles: .=.+10			" wait addresses for special files