diff --git a/src/sys/s3.s b/src/sys/s3.s
index 0037d69..8f0eb7f 100644
--- a/src/sys/s3.s
+++ b/src/sys/s3.s
@@ -317,8 +317,8 @@ rkbdi:
 wdspo:
    jms chkint1
    jms forall
-   jms dspput
-      jmp fallr
+   jms dspput			" put char (fallr "returns" here)
+      jmp fallr			" go back for next (continuation!)
    jms sleep; sfiles+6
    jms swap
    jmp wdspo
diff --git a/src/sys/s4.s b/src/sys/s4.s
index e34ddc6..09e7f97 100644
--- a/src/sys/s4.s
+++ b/src/sys/s4.s
@@ -141,6 +141,9 @@ copyz: 0
    jmp copyz i			" return
 t = t+1
 
+	" put queued character
+	" CALLED FROM PI: AVOIDS INDIRECT!!
+	" queue number in AC
 putchar: 0
 "** 01-s1.pdf page 23
    dac 9f+t
@@ -157,6 +160,14 @@ putchar: 0
    jmp putchar i
 t = t+1
 
+	" get queued character
+	" CALLED FROM PI: AVOIDS INDIRECT!!
+	" queue number in AC:
+	"  1: tty input
+	"  2: tty output
+	"  3: display keyboard
+	"  4: paper tape reader
+	"  5: paper tape punch
 getchar: 0
    jms takeq
       jmp i getchar
@@ -168,6 +179,7 @@ getchar: 0
    isz getchar
    jmp i getchar
 
+	" CALLED FROM PI: AVOIDS INDIRECT!!
 takeq: 0
    rcl
    tad lacq1
diff --git a/src/sys/s5.s b/src/sys/s5.s
index 055ed17..95c4fb3 100644
--- a/src/sys/s5.s
+++ b/src/sys/s5.s
@@ -204,9 +204,9 @@ dspput: 0
    jms dspnl			"  yes
    lac dsploc i			" get display word
    sad o400000			" TRAP?
-   jmp dspleft			"  yes
-   omq				" no: get character back
-   dac dsploc i			" save as "character 2"
+   jmp dspleft			"  yes (first character)
+   omq				" no: or in second character
+   dac dsploc i			" save both characters
    isz dsploc			" advance display pointer
    jmp i dspput
 
@@ -219,19 +219,19 @@ dspput: 0
 dspleft:
    lac dsploc			" get display pointer
    sad edspbuf			" end of the buffer?
-   jmp 1f			"  yes
-   dac 8
+   jmp 1f			"  yes: light up a button!?
+   dac 8			" no: store in index
    lac o400000			" get TRAP instruction
-   dac 8 i			" store
-   cla; llss 18+7
-   dac dsploc i
+   dac 8 i			" store as next
+   cla; llss 18+7		" shift MQ upto "char1" position
+   dac dsploc i			" store word with char1
    jmp dspput i
 
-dspnl: 0
-   lac dsplno
-   sad d33
-   jmp 1f
-   isz dsplno
+dspnl: 0			" only called once!
+   lac dsplno			" get display line number
+   sad d33			" 33?
+   jmp 1f			"  yes: light a button!
+   isz dsplno			" no: increment line number
    jmp dspnl i
 1:
    lac o2000			" get bit for push button 7
diff --git a/src/sys/s7.s b/src/sys/s7.s
index fd1e8d9..40d08ae 100644
--- a/src/sys/s7.s
+++ b/src/sys/s7.s
@@ -338,29 +338,29 @@ putcr: 0
    cla
    jmp putcr i
 
-intrp1:			" here with TTY interrupt character
-   lac d6		" get keyboard special device number
-   dac .int1		" save as interrupt source
-   lac d1
+intrp1:				" here with TTY interrupt character
+   lac d6			" get keyboard special device number
+   dac .int1			" save as interrupt source
+   lac d1			" drain tty input buffer?
    jms getchar
       skp
    jmp .-3
-   lac d2
+   lac d2			" drain tty output buffer?
    jms getchar
       skp
    jmp .-3
-   lac sfiles+0
+   lac sfiles+0			" wake ttyin sleepers
    jms wakeup
    dac sfiles+0
-   lac sfiles+1
+   lac sfiles+1			" wake ttyout sleepers
    jms wakeup
    dac sfiles+1
    jms chkint			" check if user interrupted
       jmp piret			"  no, return from PI
-   jmp 1f			" yes: return from system call
+   jmp 1f			" yes: return thru system call code (dump core)
 intrp2:				" here with display interrupt character
-   lac d7
-   dac .int2
+   lac d7			" get keyboard special device number
+   dac .int2			" save as interrupt source
    lac d3			" drain keyboard buffer?
    jms getchar
       skp
@@ -377,4 +377,4 @@ intrp2:				" here with display interrupt character
    lac 0			" get interrupt PC
    dac 020			" save as system call return PC
    lac .ac			" restore AC from interrupt
-   jmp 021			" join system call processing!!!
+   jmp 021			" join system call processing (dump core?)
diff --git a/src/sys/s8.s b/src/sys/s8.s
index 6660eb3..be013bb 100644
--- a/src/sys/s8.s
+++ b/src/sys/s8.s
@@ -93,10 +93,16 @@ o777760: 0777760
 dm3: -3
 dm1: -1
 
-9: .=.+t
-c1: .=.+1
-q1: q2;q2+90  "** ?? 98 ??
+9: .=.+t			" per-routine temp variables
+c1: .=.+1			" not used?
+q1: q2;q2+98	" ** 90?  96??	" queue element free list?
    .=.+14
+	" queues (two words each, head and tail pointers?)
+	"  1: tty input
+	"  2: tty output
+	"  3: display keyboard
+	"  4: paper tape reader
+	"  5: paper tape punch
 q2:
    .+2;0;.+2;0;.+2;0;.+2;0;.+2;0;.+2;0;.+2;0;.+2;0;.+2;0;.+2;0
    .+2;0;.+2;0;.+2;0;.+2;0;.+2;0;.+2;0;.+2;0;.+2;0;.+2;0;.+2;0