diff --git a/Makefile b/Makefile
index 315d803..afaf3ec 100644
--- a/Makefile
+++ b/Makefile
@@ -14,3 +14,10 @@ altrun: buildit
 
 clean:
 	cd build && $(MAKE) clean
+
+binaries: buildit
+	mkdir -p binaries
+	cp build/image.fs binaries/
+	cp build/boot.rim binaries/
+	cp build/unixv0.simh binaries/
+
diff --git a/README.md b/README.md
index d33504e..454f2ba 100644
--- a/README.md
+++ b/README.md
@@ -49,15 +49,9 @@ Press `ctl-e` to break out the simulator into simh
 
 ### Precompiled Binaries
 
-You can also run pdp7-unix from precompiled binaries in the [/binaries](/binaries) directory. There are **orig** binaries and **alt** binaries.
+You can also run pdp7-unix from precompiled binaries in the [/binaries](/binaries) directory. 
 
-The orig binaries use the unixv0 directory semantics as restored from the printouts.  To run pdp7-unix orig:
-
-`cd binaries/orig; pdp7 unixv0.simh`
-
-The alt binaries use the more familiar "." and ".." diretory semanatics as found in later unix.  To run pdp7-unix alt:
-
-`cd binaries/alt; pdp7 unixv0.simh`
+`cd binaries/; pdp7 unixv0.simh`
 
 ### Typical Output
 
diff --git a/binaries/boot.rim b/binaries/boot.rim
new file mode 100644
index 0000000..d5bf44b
--- /dev/null
+++ b/binaries/boot.rim
@@ -0,0 +1 @@
+ธ€‚ธ›‚ธนกฟ€ธน”ฝ€€ธนข‘€ฆถ‡ˆ•€คธน„‘€ขธนคธน‘ฑ€ธนšผ‰€ผ€ ฟฐ€ธน”‘€ฃธนข‘€ฆถ‡ˆ•€ฅธน„‘€ขธนคธน‘ฑ€œธนšผ‰€ผ€ ฐ€€€€ฐ€˜€€˜ˆ€€€ฑ€ภ
\ No newline at end of file
diff --git a/binaries/image.fs b/binaries/image.fs
new file mode 100644
index 0000000..e57d7a3
Binary files /dev/null and b/binaries/image.fs differ
diff --git a/binaries/unixv0.simh b/binaries/unixv0.simh
new file mode 100644
index 0000000..297ef35
--- /dev/null
+++ b/binaries/unixv0.simh
@@ -0,0 +1,31 @@
+set cpu 8k
+set cpu eae
+set cpu history=100
+show cpu
+
+# set up SIMH devices:
+
+# UNIX character translations (CR to NL, ESC to ALTMODE):
+set tti unix
+
+# RB09 fixed head disk:
+set rb ena
+att rb image.fs
+
+# uncomment to TELNET in GRAPHICS-2 keyboard/display(!!)
+# (requires github.com/philbudne/simh)
+set g2in ena
+att -U g2in 12345
+
+# disable hardware UNIX-7 doesn't know about:
+set lpt disa
+set drm disa
+set dt disa
+
+# show device settings:
+show dev
+
+# load and run the paper tape bootstrap
+# (loads system from disk)
+load boot.rim 010000
+go
diff --git a/src/other/brt.s b/src/other/brt.s
index 03ae284..0fe2046 100644
--- a/src/other/brt.s
+++ b/src/other/brt.s
@@ -112,7 +112,7 @@ jmp start
    isz sp
    jmp fetch
 
-.getchr: .+1
+.getchar: .+1
    s 2
    n 8
    n 7
@@ -125,7 +125,7 @@ jmp start
    isz sp
    jmp fetch
 
-.putchr: .+1
+.putchar: .+1
    s 2
    n 8
    n 7
@@ -230,29 +230,23 @@ flush: 0
    jmp flush i
 
 initio: 0
+   law .argv      " build argument list
+   dac 8          " auto-inc pointer argvp = &argv[-1]
    lac 017777 i
-"   sad d4
-   jmp 2f
-   sad d8
-   jmp 1f
+   cll rtr
+   dac 8 i        " *++argvp = arg count
+   cma
+   tad d1
+   dac t1         " count = -argv[0]
+   lac 017777
+   dac lastv      " set top of heap
+   tad d1         " ac = addr of arg0
+1: 
+   dac 8 i        " *++argvp = ac
+   tad d4         " ac += 4
+   isz t1         " while ++count != 0
+   jmp 1b
 
-   law 9
-   tad 017777
-   dac .+3
-   law 017
-   sys creat; ..
-   spa
-   jmp stop
-   dac .fout
-1:
-   law 5
-   tad 017777
-   dac .+2
-   sys open; ..; 0
-   spa
-   jmp stop
-   dac .fin
-2:
    lac lastv
    dac eibufp
    dac cibufp
@@ -280,7 +274,7 @@ iflg: 0
 eobufp: 0
 cobufp: 0
 oflg: 0
-lastv: 017770
+lastv: 0
 
 o777: 0777
 d4:o4: 4
diff --git a/src/other/brtb.b b/src/other/brtb.b
index 8439a52..34d792c 100644
--- a/src/other/brtb.b
+++ b/src/other/brtb.b
@@ -2,68 +2,61 @@
 
 char(s, n) {
   if (n & 1) return(s[n/2] & 0777);
-  return ((s[n/2]/512) & 0777);
+  return((s[n/2]/512) & 0777);
 }
 
 lchar(s, n, c) {
   if (n & 1) s[n/2] = (s[n/2] & 0777000) | c;
   else s[n/2] = (s[n/2] & 0777) | (c*512);
+  return(c);
 }
 
-putstr(s) {
-  auto c, i;
+putnum(n, b) {
+  auto a, d;
 
-  i = 0;
-  while ((c = char(s,i)) != '*e') {
-    putchr(c);
-    i = i+1;
+  d = 0;
+  if (n < 0) {
+    n = -n;
+    if (n < 0) {
+      n = n-1;
+      d = 1;
+    } else
+      putchar('-');
   }
-}
-
-putnum(n) {
-  if (n > 9) {
-    putnum(n / 10);
-    n = n % 10;
-  }
-  putchr(n + '0');
-}
-
-octal(n) {
-  if (n > 7) {
-    octal(n / 8);
-    n = n & 7;
-  }
-  putchr(n + '0');
+  if (a = n/b)
+    putnum(a, b);
+  putchar(n%b + '0' + d);
 }
 
 printf(fmt,x1,x2,x3,x4,x5,x6,x7,x8,x9) {
-  auto adx, c, i;
+  auto adx, a, c, i, n;
   
   i = 0;
   adx = &x1;
 loop:
-  while ((c = char(fmt,i)) != '%') {
-    if (c=='*e')
+  while ((c = char(fmt, i)) != '%') {
+    if (c == '*e')
       return;
-    putchr(c);
+    putchar(c);
     i = i+1;
   }
   i = i+1;
-  c = char(fmt,i);
-  if (c=='d') {
-    if (*adx < 0) {
-      putchr('-');
-      *adx = -*adx;
-    }  
-    putnum(*adx);
-  } else if (c=='o') 
-    octal(*adx);
+  a = *adx;
+  c = char(fmt, i);
+  if (c=='d')
+    putnum(a, 10);
+  else if (c=='o') 
+    putnum(a, 8);
   else if (c=='c')
-    putchr(*adx);
-  else if (c=='s')
-    putstr(*adx);
-  else {
-    putchr('%');
+    putchar(a);
+  else if (c=='s') {
+    n = 0;
+    while ((c = char(a, n)) != '*e') {
+      putchar(c);
+      n = n+1;
+    }
+  } else {
+    putchar('%');
     goto loop;
   }
   i = i+1;
diff --git a/src/other/ctype.b b/src/other/ctype.b
new file mode 100644
index 0000000..8e05611
--- /dev/null
+++ b/src/other/ctype.b
@@ -0,0 +1,9 @@
+/* ctype.b - character types */
+
+isalpha(c) {
+  return((c >= 'a' & c <= 'z') | (c >= 'A' & c <= 'Z'));
+}
+
+isdigit(c) {
+  return(c >= '0' & c <= '9');
+}
diff --git a/src/other/string.b b/src/other/string.b
new file mode 100644
index 0000000..7731be8
--- /dev/null
+++ b/src/other/string.b
@@ -0,0 +1,58 @@
+/* string.b - B string library
+
+   mostly from: https://www.bell-labs.com/usr/dmr/www/btut.html
+*/
+
+strcopy(sl, s2) {
+  auto i;
+  i = 0;
+  while (lchar(sl,i,char(s2,i)) != '*e')
+    i = i+1;
+  return(s1);
+}
+
+strcat(s1, s2) {
+  auto i,j;
+  i = j = 0;
+  while (char(s1,i) != '*e')
+    i = i+1;
+  while(lchar(s1,i,char(s2,j)) != '*e') {
+    i = i+1;
+    j = j+1;
+  }    
+  return(s1);
+}
+
+strlen(s) {
+  auto i;
+  i = 0;
+  while (char(s,i) != '*e')
+    i = i+1;
+  return(i);
+}
+
+strcmp(s1, s2) {
+  auto c,i;
+  i = 0;
+  while ((c=char(s1,i)) == char(s2,i)) {
+    if (c == '*e')
+      return(0);
+    i = i+1;
+  }
+  return(c - char(s2,i));
+}
+
+/* convert command line argument into a string */
+strarg(s, a) {
+  auto i, c;
+  i = 0;
+  while (i < 8) {
+    if ((c = char(a,i)) == ' ')
+      goto done;
+    lchar(s,i,c);
+    i = i+1;
+  }
+done:
+  lchar(s,i,'*e');
+  return(s);
+}
diff --git a/src/other/test.b b/src/other/test.b
index c0259a8..e398c3d 100644
--- a/src/other/test.b
+++ b/src/other/test.b
@@ -7,14 +7,41 @@
    perl a7out test.out
 */
 
+/* convert command line argument into a string */
+strarg(s, a) {
+  auto i, c;
+  i = 0;
+  while (i < 8) {
+    if ((c = char(a,i)) == ' ')
+      goto done;
+    lchar(s,i,c);
+    i = i+1;
+  }
+done:
+  lchar(s,i,'*e');
+  return(s);
+}
+
 main {
-  extrn fname, fin;
-  auto ch,p;
+  extrn fname, fin, fout, argv;
+  auto ch,p,n,str 5;
 
   p = 017777;
   printf("mem[0%o] = 0%o*n",p,*p);
   printf("mem[0%o] = %d*n",*p,**p);
   
+  printf("argv = %d*n",argv);
+  printf("**argv = %d*n",*argv);
+  printf("argv[0] = %d*n",argv[0]);
+  n = 0;
+  while (n < argv[0]) {
+    n = n+1;
+    printf("argv[%d] = 0%o *"%s*"*n",n,argv[n],strarg(str,argv[n]));
+  }
+
+  printf("array(0)  = 0%o*n",array(0));
+  printf("array(64) = 0%o*n",array(64));
+  printf("array(0)  = 0%o*n",array(0));
   
 /*  fin = open(fname, 0); */
   fin = open("abc     ", 0);
diff --git a/src/sys/s1.s b/src/sys/s1.s
index a7a07ab..7532526 100644
--- a/src/sys/s1.s
+++ b/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?
diff --git a/src/sys/s2.s b/src/sys/s2.s
index 4195e78..c430198 100644
--- a/src/sys/s2.s
+++ b/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
diff --git a/src/sys/s3.s b/src/sys/s3.s
index af143d0..386dbfe 100644
--- a/src/sys/s3.s
+++ b/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
diff --git a/src/sys/s4.s b/src/sys/s4.s
index fe07ba5..8f273e3 100644
--- a/src/sys/s4.s
+++ b/src/sys/s4.s
@@ -3,60 +3,61 @@
 
 	" allocate a free disk block for a file (data or indirect)
 alloc: 0
-   -1			" Decrement the # free block numbers in the cache
-   tad s.nfblks		" kept at s.fblks. Jump to 1f if no free blocks left.
-   spa
-   jmp 1f
+   -1			" decrement the count
+   tad s.nfblks		" of free blocks at s.fblks
+   spa			" any left?
+   jmp 1f		"  no
    dac s.nfblks		" Update the count of free block numbers
-   tad fblksp
-   jms laci
-   dac 9f+t
-   jms copyz; dskbuf; 64
-   lac 9f+t
-   jms dskwr
-   dzm .savblk
-   lac 9f+t
+   tad fblksp		" get pointer to last valid entry in s.fblks
+   jms laci		" fetch the word
+   dac 9f+t		" save in t0
+   jms copyz; dskbuf; 64	" zero dskbuf
+   lac 9f+t		" get block number back
+   jms dskwr		" write out the zeros
+   dzm .savblk		" cancel system block write
+   lac 9f+t		" get the block number back
    jmp alloc i		" Return from routine
 1:
-   lac s.nxfblk
-   sna
+   lac s.nxfblk		" next block with list of free blocks
+   sna			" any?
    jms halt " OUT OF DISK
-   dac s.fblks
-   jms dskrd
-   lac dskbuf
-   dac s.nxfblk
-   jms copy; dskbuf+1; s.fblks+1; 9
-   lac d10
+   dac s.fblks		" save as first free block #
+   jms dskrd		" read the block
+   lac dskbuf		" get first word (pointer to next in chain)
+   dac s.nxfblk		" save as new "next"
+   jms copy; dskbuf+1; s.fblks+1; 9	" copy remaining 9 as free
+   lac d10		" reset free count
    dac s.nfblks
    jmp alloc+1
 
 	" free the disk block whose number is in AC
 free: 0
-   lmq
-   lac s.nfblks
-   sad d10
-   jmp 1f
-   tad fblksp
-   dac 9f+t
-   lacq
-   dac 9f+t i
-   dzm .savblk
-   isz s.nfblks
-   jmp free i
+   lmq			" save block in MQ
+   lac s.nfblks		" get number of free blocks
+   sad d10		" 10?
+   jmp 1f		"  yes
+   tad fblksp		" no: get addr in s.fblks to store new block in
+   dac 9f+t		" save pointer
+   lacq			" get block number
+   dac 9f+t i		" save it in s.fblks
+   dzm .savblk		" cancel system block write
+   isz s.nfblks		" increment free count
+   jmp free i		" return
 1:
-   lac s.nxfblk
-   dac dskbuf
-   jms copy; s.fblks+1; dskbuf+1; 9
-   lacq
-   dac s.nxfblk
-   jms dskwr
-   dzm .savblk
-   lac d1
-   dac s.nfblks
-   jmp free i				" Return from the routine
+   lac s.nxfblk		" get head of free chain
+   dac dskbuf		" save (as chain ptr) in first word of disk buf
+   jms copy; s.fblks+1; dskbuf+1; 9	" with 9 of the 10 free blocks
+   lacq			" get the newly freed block back
+   dac s.nxfblk		" save as new head of free chain
+   jms dskwr		" write dskbuf to the newly freed block
+   dzm .savblk		" cancel system block write
+   lac d1		" reset free count to one
+   dac s.nfblks		" (the first word in s.fblks)
+   jmp free i		" Return from the routine
 t = t+1
 
 	" load AC indirect (without using indirect!)
+	" need to avoid use of indirect in interrupt service routines
 	" AC/ address
 	"   jms laci
 	" AC/ contents of address
@@ -141,92 +142,105 @@ 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
-   cla
-   jms takeq
-      jmp putchar i
-   tad o40001
-   dac .+4
-   lac 9f+t
-   jms putq
-   lac char
-   dac q2+1 ..
-   isz putchar
-   jmp putchar i
-t = t+1
+	" Character queue management routines
+	" (CALLED FROM PI: USE OF INDIRECT AVOIDED!)
 
-	" get queued character
-	" CALLED FROM PI: AVOIDS INDIRECT!!
-	" queue number in AC:
+	" Queue numbers:
+	"  0: free list
 	"  1: tty input
 	"  2: tty output
 	"  3: display keyboard
 	"  4: paper tape reader
 	"  5: paper tape punch
-getchar: 0
+
+	" queue headers are two words: "first" and "last"(??)
+	" queue entries are two words: "next" and "char"
+
+	" put queued character
+	" character to store in "char"
+	" queue number in AC
+
+putchar: 0
+"** 01-s1.pdf page 23
+   dac 9f+t		" save queue number in t0
+   cla			" get entry from free list
    jms takeq
-      jmp i getchar
-   tad o200001
+      jmp putchar i	" none free: return w/o skip
+   tad o40001		" turn into "dac addr+1"
+   dac .+4
+   lac 9f+t		" get queue number back
+   jms putq		" add entry
+   lac char		" get char
+   dac q2+1 ..		" save in second word of queue entry
+   isz putchar		" give skip return
+   jmp putchar i
+t = t+1
+
+	" get queued character
+	" queue number in AC
+	" returns with skip if something found
+getchar: 0
+   jms takeq		" get entry from head of queue
+      jmp i getchar	"  nothing there: return w/o skip
+   tad o200001		" turn into "lac qentry+1" (fetch stored char)
    dac .+3
    cla
-   jms putq
-   lac q2+1 ..
-   isz getchar
+   jms putq		" put qentry on free list
+   lac q2+1 ..		" fetch queued character(!!!)
+   isz getchar		" give skip return
    jmp i getchar
 
-	" CALLED FROM PI: AVOIDS INDIRECT!!
+	" fetch first entry from a queue
+	" queue number in AC
+	" returns with skip if something dequeued
 takeq: 0
-   rcl
-   tad lacq1
+   rcl			" multiply queue number by two
+   tad lacq1		" add "lac q1"
    dac .+7
-   tad o640000
+   tad o640000		" turn "lac" into "dac"
    dac .+17
-   tad d1
+   tad d1		" increment addr
    dac .+14
-   tad o500000
+   tad o500000		" turn "dac" into "sad"
    dac .+5
-   lac q1 ..
-   sna
-   jmp takeq i
+   lac q1 ..		" load queue head
+   sna			" non-zero?
+   jmp takeq i		"  no: return zero w/o skip
    dac lnkaddr
-   sad q1+1 ..
-   jmp .+5
-   tad o200000
-   dac .+1
-   lac q2 ..
+   sad q1+1 ..		" different from tail(??)
+   jmp .+5		"  no -- (last entry?)
+   tad o200000		" yes: turn into lac
+   dac .+1		" save lac
+   lac q2 ..		" get next pointer from queue entry
    jmp .+3
-   cla
-   dac q1+1 ..
-   dac q1 ..
-   isz takeq
-   lac lnkaddr
+   cla			" here with head == tail(??)
+   dac q1+1 ..		" clear tail
+   dac q1 ..		" save (clear) head
+   isz takeq		" give skip return
+   lac lnkaddr		" return queue entry pointer
    jmp i takeq
 
+	" save queue entry (at lnkaddr) to a queue (queue number in AC)
 putq: 0
-   rcl
-   tad dacq1
+   rcl			" multiply by two
+   tad dacq1		" turn into "dac qhead"
    dac .+14
-   tad d1
+   tad d1		" turn into "dac qtail"
    dac .+13
-   tad o140000
+   tad o140000		" turn into "lac qtail"
    dac .+1
-   lac q1-1 ..
+   lac q1-1 ..		" fetch tail
 "** 01-s1.pdf page 24
-   sna
-   jmp .+6
-   tad o40000
+   sna			" non-zero?
+   jmp .+6		"  no: is zero
+   tad o40000		" turn into "dac qentry" (append to queue)
    dac .+2
-   lac lnkaddr
-   dac q2 ..
+   lac lnkaddr		" get new entry
+   dac q2 ..		" append to tail entry
    jmp .+3
-   lac lnkaddr
-   dac q1 ..
-   dac q1+1 ..
+   lac lnkaddr		" here with tail == 0
+   dac q1 ..		" save new entry as head
+   dac q1+1 ..		" save new tail
    jmp putq i
 
 	" NOTE!! srcdbs, collaps, dskrd, dskwr share the same "temp" vars:
diff --git a/src/sys/s5.s b/src/sys/s5.s
index af6ed77..55f242c 100644
--- a/src/sys/s5.s
+++ b/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
 
diff --git a/src/sys/s6.s b/src/sys/s6.s
index 5ba1097..6adf94d 100644
--- a/src/sys/s6.s
+++ b/src/sys/s6.s
@@ -99,6 +99,8 @@ namei: 0
    jmp 1b		"  yes: keep going
    jmp namei i		" Didn't find it, return zero in AC (without skip)
 t = t+2
+
+		" NOTE: iget/iput share "temp" vars!!!
                         " Given an i-number in AC, fetch that i-node
                         " from disk and store it in the inode buffer
 iget: 0
@@ -113,49 +115,50 @@ iget: 0
    cll; mul; 12		" Multiply the i-num within the block by 12
    lacq			" to get the offset into the block
    tad dskbufp		" Add on the base of the disk buffer
-   dac 9f+t
+   dac 9f+t		" save pointer into dskbuf in "t0"
    dac .+2
    jms copy; ..; inode; 12	" Copy 12 words from buffer to inode
    jmp iget i		" and return
 
 iput: 0
-   lac 9f+t+1
-   jms dskrd
-   law inode-1
-   dac 8
+   lac 9f+t+1		" get block number saved by iget
+   jms dskrd		" read the block
+   law inode-1		" pointer to "in core" inode
+   dac 8		" in index 8
    -1
-   tad 9f+t
-   dac 9
-   -12
-   dac 9f+t+2
+   tad 9f+t		" get saved pointer into buffer
+   dac 9		" in index 9
+   -12			" 12 word loop count
+   dac 9f+t+2		" in t2
 1:
-   lac 8 i
+   lac 8 i		" fetch source word
 
 "** 01-s1.pdf page 36
 
-   sad 9 i
-   skp
-   jmp 2f
-   isz 9f+t+2
-   jmp 1b
-   jmp iput i
-2:
-   -1
+   sad 9 i		" differs from disk?
+   skp			"  no:
+   jmp 2f		"   yes: 
+   isz 9f+t+2		" no difference: done?
+   jmp 1b		"  no: keep going
+   jmp iput i		" yes: return w/o writing to disk
+2:			" here with in-core inode changed
+   -1			" back up both pointers
    tad 8
    dac 8
    -1
    tad 9
    dac 9
 1:
-   lac 8 i
-   dac 9 i
-   isz 9f+t+2
-   jmp 1b
-   lac 9f+t+1
-   jms dskwr
-   jmp iput i
+   lac 8 i		" fetch word
+   dac 9 i		" copy to dskbuf
+   isz 9f+t+2		" done?
+   jmp 1b		"  no: keep going
+   lac 9f+t+1		" get block number
+   jms dskwr		" write back to disk
+   jmp iput i		" return
 t = t+3
 
+	" NOTE! dget/dput share "temp" vars
 	" allocate directory entry
 	" AC/ entry number
 dget: 0
@@ -164,30 +167,31 @@ dget: 0
    dac 9f+t			" save in t0
    jms pget			" get free disk block
    dac 9f+t+1			" save in t1
-   jms dskrd
-   lac 9f+t
-   and o77
-   tad dskbufp
-   dac 9f+t+2
-   dac .+2
-   jms copy; ..; dnode; 8
-   lac 9f+t
-   tad d8
-   jms betwen; d0; i.size
-      skp
-   jmp dget i
-   jms dacisize
-   dzm d.i
-   jmp dget i
+   jms dskrd			" read block
+   lac 9f+t			" get word number
+   and o77			" get word within block
+   tad dskbufp			" make pointer into dskbuf
+   dac 9f+t+2			" save in t2
+   dac .+2			" save as copy source
+   jms copy; ..; dnode; 8	" copy entry into dnode
+   lac 9f+t			" get word number
+   tad d8			" of end of new node
+   jms betwen; d0; i.size	" already allocated?
+      skp			"  no
+   jmp dget i			"   yes: return
+   jms dacisize			" store new file size
+   dzm d.i			" mark new entry as free
+   jmp dget i			" return
 
+	" write directory entry (back) to disk
 dput: 0
-   lac 9f+t+1
-   jms dskrd
-   lac 9f+t+2
-   dac .+3
-   jms copy; dnode; ..; 8
-   lac 9f+t+1
-   jms dskwr
+   lac 9f+t+1			" get disk block number back
+   jms dskrd			" read into dskbuf
+   lac 9f+t+2			" get pointer into dskbuf
+   dac .+3			" save as copy dest
+   jms copy; dnode; ..; 8	" copy into dskbuf
+   lac 9f+t+1			" get disk block number
+   jms dskwr			" write back to disk
    jmp dput i
 
 t = t+3
@@ -262,6 +266,10 @@ pget: 0
    jmp pget i				" return it
 t = t+3
 
+	" write to file referenced by loaded inode
+	" AC/ file offset
+	"    jms iwrite; addr; count
+
 iwrite: 0
    dac 9f+t				" save arg in t0
    lac iwrite				" load return address
@@ -273,14 +281,14 @@ iwrite: 0
    dac iwrite				" save as iwrite instruction
    jmp 1f
 
-	" iread from file referenced by loaded inode
+	" read from file referenced by loaded inode
 	" AC/ file offset
 	"    jms iread; addr; count
 iread: 0
    dac 9f+t				" save offset in t0
    lac cnop				" get nop
    dac iwrite				" save as iwrite instruction
-1:
+1:					" common code for iread/iwrite
    -1
    tad iread i				" get word before return addr
    dac 10				" store in index 10 & 11
@@ -289,7 +297,7 @@ iread: 0
    lac iread i				" load addr
    dac 9f+t+1				" save in t1
    isz iread				" increment return addr
-   lac o70000
+   lac o70000				" get max file size
    xct iwrite				" skip if write
    lac i.size				"  read: get file size
    cma
@@ -299,10 +307,10 @@ iread: 0
       lac 9f+t+1
    dac 9f+t+2
    cma
-   tad d1
-   sna
-   jmp iread i
-   dac 9f+t+1
+   tad d1				" subtract offset
+   sna					" offset == size?
+   jmp iread i				"  yes, return
+   dac 9f+t+1				" save size-offset in t1
 1:
    lac 9f+t
    jms pget
@@ -312,7 +320,7 @@ iread: 0
    and o77
    tad dskbufp
    tad dm1
-   xct iwrite
+   xct iwrite				" skip if write
    jmp .+3
    dac 10
 cskp:
diff --git a/src/sys/s7.s b/src/sys/s7.s
index f6b2a7a..7f6a999 100644
--- a/src/sys/s7.s
+++ b/src/sys/s7.s
@@ -1,28 +1,28 @@
 "** 01-s1.pdf page 41
 " s7
 
-pibreak:			" priority interrupt break processing "chain"
-   dac .ac			" save interrupt AC
+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
@@ -49,141 +49,142 @@ 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
+1: dssf			" disk flag set?
+   jmp 1f		"  no
 
-   -1				" set .dskb = -1
+   -1			" set .dskb = -1
    dac .dskb
 
 "** 01-s1.pdf page 42
 
-   dsrs				" get disk status in .dske
+   dsrs			" get disk status in .dske
    dac .dske
-   dscs				" clear status register
+   dscs			" clear status register
    jmp piret
 
 		"** BEGIN CROSSED OUT
-1: lds				" load display status (see 03-scope.pdf pg 25)
-   sma ral			" display trap set? (and rotate left)
-   jmp 1f			"  not set
-   cdf				" display done executing; clear display flags
+1: lds			" load display status (see 03-scope.pdf pg 25)
+   sma ral		" display trap set? (and rotate left)
+   jmp 1f		"  not set
+   cdf			" display done executing; clear display flags
    lac .dspb
    sna
-   jmp piret			" return now if .dspb == 0
+   jmp piret		" return now if .dspb == 0
    tad dm3
    sna
-   jmp dsprestart		" start display if .dspb == 3
-   dac .dspb			" otherwise, .dspb -= 3 and return
+   jmp dsprestart	" start display if .dspb == 3
+   dac .dspb		" otherwise, .dspb -= 3 and return
    jmp piret
 dsprestart:
    lac d1
-   dac .dspb			" set .dspb = 1
-   lac dspbufp			" load display buf pointer
-   beg				" start display processor
+   dac .dspb		" set .dspb = 1
+   lac dspbufp		" load display buf pointer
+   beg			" start display processor
    -10
-   dac .dsptm			" set .dsptm = -10 (10 ticks)
+   dac .dsptm		" set .dsptm = -10 (10 ticks)
    jmp piret
 
-1: sma ral			" edges flag set?? (and rotate)
-   jmp .+3			"  no
-   raef				" "resume after edges flag"
-   jmp piret			" return
-   sma				" light pen flag?
-   jmp 1f			"  no
-   lda				" G-2: load display address
-   dac .lpba			" save
-   rlpd				" G-2: resume after light pen stop
+1: sma ral		" edges flag set?? (and rotate)
+   jmp .+3		"  no
+   raef			" "resume after edges flag"
+   jmp piret		" return
+   sma			" light pen flag?
+   jmp 1f		"  no
+   lda			" G-2: load display address
+   dac .lpba		" save
+   rlpd			" G-2: resume after light pen stop
    jmp piret
 
-1: ksf				" (TTY) keyboard flag set?
-   jmp 1f			"  no
+1: ksf			" (TTY) keyboard flag set?
+   jmp 1f		"  no
 
-   lac ttydelay			" get TTY delay
-   sma				" minus (waiting for output)?
-   isz ttydelay			"  no: increment??? (make more positive)
-   krb				" read keyboard buffer
-   dac char			" save in char
-   sad o375			" interrupt char (TTY ALT MODE?)
-   jmp intrp1			"  yes
+   lac ttydelay		" get TTY delay
+   sma			" minus (waiting for output)?
+   isz ttydelay		"  no: increment??? (make more positive)
+   krb			" read keyboard buffer
+   dac char		" save in char
+   sad o375		" interrupt char (TTY ALT MODE?)
+   jmp intrp1		"  yes
    lac d1
    jms putchar
       dzm char
-   lac sfiles+0			" get sleep word for ttyin
-   jms wakeup			" wake processes
-   dac sfiles+0			" clear sleep word
-   lac char			" get character
-   sad o212			" new line (with parity)??
-   skp				"  yes
-   jmp piret			"   no: done
-   lac sfiles+1			" get ttyout sleep word
-   sma				" highest bit set?
-   xor o400000			" no, make it so (why???)
-   dac sfiles+1			" save back
+   lac sfiles+0		" get sleep word for ttyin
+   jms wakeup		" wake processes
+   dac sfiles+0		" clear sleep word
+   lac char		" get character
+   sad o212		" new line (with parity)??
+   skp			"  yes
+   jmp piret		"   no: done
+   lac sfiles+1		" get ttyout sleep word
+   sma			" highest bit set?
+   xor o400000		" no, make it so (why???)
+   dac sfiles+1		" save back
 
 "** 01-s1.pdf page 43
 
-   jms putcr			" output CR next
-   jms ttyrestart		" start output
+   jms putcr		" output CR next
+   jms ttyrestart	" start output
    jmp piret
 
-1: tsf				" TTY output flag set?
-   jmp 1f			"  no
+1: tsf			" TTY output flag set?
+   jmp 1f		"  no
 
-   tcf				" yes: clear flag
-   jms ttyrestart		" transmit next character
+   tcf			" yes: clear flag
+   jms ttyrestart	" transmit next character
    jmp piret
 
 ttyrestart: 0
-   lac ttydelay			" get tty delay
-   spa				" positive?
-   jmp ttyrestart i		"  no: keep waiting
-   lac nttychar			" get pending CR, if any
-   dzm nttychar			" clear it
-   sza				" need to send CR?
-   jmp 3f			"  yes
-   isz ttydelay			" increment ttydelay (make more positive)
+   lac ttydelay		" get tty delay
+   spa			" positive?
+   jmp ttyrestart i	"  no: keep waiting
+   lac nttychar		" get pending CR, if any
+   dzm nttychar		" clear it
+   sza			" need to send CR?
+   jmp 3f		"  yes
+   isz ttydelay		" increment ttydelay (make more positive)
    lac d2
-   jms getchar			" get a character
-      jmp 2f			"  none found??
+   jms getchar		" get a character
+      jmp 2f		"  none found??
 3:
-   tls				" start output
-   sad o12			" newline?
-   jms putcr			" yes: put CR next
-   sad o15			" CR?
-   skp				"  yes
-   jmp ttyrestart i		"   no: return
-   lac ttydelay			" get current tty delay
-   tad o20			" bump by 16
-   rcr				" divide by two
-   cma				" complement
-   dac ttydelay			" save
+   tls			" start output
+   sad o12		" newline?
+   jms putcr		" yes: put CR next
+   sad o15		" CR?
+   skp			"  yes
+   jmp ttyrestart i	"   no: return
+   lac ttydelay		" get current tty delay
+   tad o20		" bump by 16
+   rcr			" divide by two
+   cma			" complement
+   dac ttydelay		" save
    jmp ttyrestart i
 2:
-   lac sfiles+1			" run out of characters to send: wake user(s)
+   lac sfiles+1		" run out of characters to send: wake user(s)
    jms wakeup
    dac sfiles+1
    jmp ttyrestart i	"** written arrow up 2 copies
 
 			"** BEGIN CROSSED OUT
-1: sck				" Graphic-2 keyboard flag set?
-   jmp 1f			"  no.
+1: sck			" Graphic-2 keyboard flag set?
+   jmp 1f		"  no.
 
-   cck				" yes: clear flag
-   lck				" read character
+   cck			" yes: clear flag
+   lck			" read character
    dac char
-   sad o33			" code 33 (ESCAPE?)
-   jmp intrp2			"  yes: mark interrupt
+   sad o33		" code 33 (ESCAPE?)
+   jmp intrp2		"  yes: mark interrupt
    lac d3
    jms putchar
       nop
@@ -192,21 +193,21 @@ ttyrestart: 0
    dac sfiles+2
    jmp piret
 
-1: rsf				" paper tape ready?
-   jmp 1f			"  no
+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:
@@ -239,43 +240,43 @@ ttyrestart: 0
    dac sfiles+3
    jmp piret
 
-1: psf					" paper tape ready?
-   jmp 1f				"  no
+1: psf			" paper tape punch ready?
+   jmp 1f		"  no
 
-   pcf					" clear ptp flag
+   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
+   jms getchar		" get next char
+   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?
-   jmp 1f				"  no
+1: spb			" any graphic-2 push button?
+   jmp 1f		"  no
 
-   cpb					" clear push button flag
-   lpb					" load push button value
+   cpb			" clear push button flag
+   lpb			" load push button value
    dac pbsflgs+1
 
 "** 01-s1.pdf page 45
 
-   and o2000				" get push button 7
-   sna					" set?
-   jmp piret				"  no: done
-   jms dspinit				" yes: reset display buffer
-   lac sfiles+6				" wake up anyone sleeping on display
+   and o2000		" get push button 7
+   sna			" set?
+   jmp piret		"  no: done
+   jms dspinit		" yes: reset display buffer
+   lac sfiles+6		" wake up anyone sleeping on display
    jms wakeup
    dac sfiles+6
-   cla					" clear button lights
+   cla			" clear button lights
    wbl
    jmp piret	"** END CROSSED OUT
 
-1: crsf					" card reader flag set?
-   jmp 1f				"  no
+1: crsf			" card reader flag set?
+   jmp 1f		"  no
 
    crrb
    dac crchar
@@ -283,14 +284,14 @@ ttyrestart: 0
    dac crread
    jmp piret
 
-1: crrb					" read card reader buffer??
+1: crrb			" read card reader buffer??
 
-piret:					" return from priority interrupt
-   lac 0				" get LINK/PC
-   ral					" restore LINK
-   lac .ac				" restore AC
-   ion					" reenable interrupts
-   jmp 0 i				" return from interrupt
+piret:			" return from priority interrupt
+   lac 0		" get LINK (in bit 0)
+   ral			" restore LINK
+   lac .ac		" restore AC
+   ion			" reenable interrupts
+   jmp 0 i		" return from interrupt
 
 	" wake sleeping processes
 	" NOTE!! Called from interrupt service, so avoids indirect!!!
@@ -299,35 +300,35 @@ piret:					" return from priority interrupt
 	"   jms wakeup
 	" AC/ 0 (to store in sfiles word)
 wakeup: 0
-   dac 9f+t				" save vector in t0
+   dac 9f+t		" save vector in t0
    -mnproc
-   dac 9f+t+1				" loop count in t1
-   lac tadu				" get "tad ulist"
+   dac 9f+t+1		" loop count in t1
+   lac tadu		" get "tad ulist"
    dac 2f
-   lac dacu				" get "dac ulist"
+   lac dacu		" get "dac ulist"
    dac 2f+1
 1:
    lac 9f+t
-   ral					" rotate vector up one
+   ral			" rotate vector up one
    dac 9f+t
-   sma					" high bit set?
-   jmp 2f+2				"  no: skip the fun
-   lac o700000				" yes: decrement process status (wake)
-2: tad ..				" (avoiding indirect)
+   sma			" high bit set?
+   jmp 2f+2		"  no: skip the fun
+   lac o700000		" yes: decrement process status (wake)
+2: tad ..		" (avoiding indirect)
    dac ..
-   lac 2b				" advance tad operand by 4 words
+   lac 2b		" advance tad operand by 4 words
    tad d4
    dac 2b
-   lac 2b+1				" advance tad operand by 4 words
+   lac 2b+1		" advance tad operand by 4 words
    tad d4
    dac 2b+1
-   isz 9f+t+1				" done?
-   jmp 1b				"  no, keep going
-   cla					" return zero in AC
+   isz 9f+t+1		" done?
+   jmp 1b		"  no, keep going
+   cla			" return zero in AC
    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
@@ -337,43 +338,43 @@ 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			" drain tty input buffer?
+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			" drain tty output buffer?
+   lac d2		" drain tty output buffer?
    jms getchar
       skp
    jmp .-3
-   lac sfiles+0			" wake ttyin sleepers
+   lac sfiles+0		" wake ttyin sleepers
    jms wakeup
    dac sfiles+0
-   lac sfiles+1			" wake ttyout sleepers
+   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 thru system call code (dump core)
-intrp2:				" here with display interrupt character
-   lac d7			" get keyboard special device number
-   dac .int2			" save as interrupt source
-   lac d3			" drain keyboard buffer?
+   jms chkint		" check if user interrupted
+      jmp piret		"  no, return from PI
+   jmp 1f		" yes: return thru system call code (dump core)
+intrp2:			" here with display interrupt character
+   lac d7		" get keyboard special device number
+   dac .int2		" save as interrupt source
+   lac d3		" drain keyboard buffer?
    jms getchar
       skp
    jmp .-3
-   lac sfiles+2			" wake up any "keyboard" sleepers
+   lac sfiles+2		" wake up any "keyboard" sleepers
    jms wakeup
    dac sfiles+2
-   lac sfiles+6			" wake up any "display" sleepers
+   lac sfiles+6		" wake up any "display" sleepers
    jms wakeup
    dac sfiles+6
-   jms chkint			" check if user interrupted
-      jmp piret			"  no, return from PI
+   jms chkint		" check if user interrupted
+      jmp piret		"  no, return from PI
 1:
-   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 (dump core?)
+   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 (dump core?)
diff --git a/src/sys/s8.s b/src/sys/s8.s
index 4cf8fb4..0d84bf9 100644
--- a/src/sys/s8.s
+++ b/src/sys/s8.s
@@ -95,28 +95,30 @@ dm1: -1
 
 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?)
+	" character queues (two words each, head and tail pointers?)
+	"  0: free list
 	"  1: tty input
 	"  2: tty output
 	"  3: display keyboard
 	"  4: paper tape reader
 	"  5: paper tape punch
-q2:
+q1: q2;q2+98			" queue element free list
+   .=.+14			" room for 7 queues (5 used)
+q2:				" queue elements (and two words padding??)
    .+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
    .+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
    .+2;0;.+2;0;.+2;0;.+2;0;.+2;0;.+2;0;.+2;0;.+2;0;.+2;0;0;0
-dsploc: .=.+1
-dsplno: .=.+1
+dsploc: .=.+1			" pointer into dspbuf
+dsplno: .=.+1			" display current line number
 dspbuf:
    0065057;0147740;0160000	" display commands: see 03-scope.pdf pg 20
 	" PARAM: clear blink, clear light pen, scale=1, intensity=3
 	" 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
@@ -145,29 +147,30 @@ 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
-		" (bit vector of waiting processes?)
+		" (bit vectors of waiting processes?)
+		" bit zero (MSB) is special, bit 1 first ulist entry, ....
 		" offsets:	0: ttyin, 1: ttyout, 2: keyboard,
 		"		3: ptr,   4: ptp,    6: display
-dpdata:
+dpdata:				" dataphone data
    dpstat: .=.+1
    dpread: .=.+1
    dpwrite: .=.+1
    dpchar: .=.+1
-dspdata:
+dspdata:			" display data
    .dspb: .=.+1
    .lpba: .=.+1	"** 4 written on listing
-crdata:
+crdata:				" card reader data
    crread: .=.+1
    crchar: .=.+1
 sysdata:			" system data 64 words saved to disk
@@ -176,7 +179,7 @@ sysdata:			" system data 64 words saved to disk
    s.fblks: .=.+10		" cached free block numbers
    s.uniq: .=.+1		" next unique value
    s.tim: .=.+2			" (up?)time in 60Hz ticks (low, high)
-	" process table
+	" user (process) table
 	" first word
 	"   bits 0:2 -- status
 	"	0: free slot
@@ -187,7 +190,7 @@ sysdata:			" system data 64 words saved to disk
 	"   bits 3:17 -- disk swap address/8
 	" second word: process pid
 	" third word:  smes/rmes status:
-	"	0: not waiting
+	"	 0: not waiting
 	"	-1: this process waiting (rmes)
 	"	other: complement of sender pid
 	" fourth word: smes message
@@ -242,7 +245,7 @@ dnode:				" directory entry:
    d.name: .=.+4		" name (space padded)
    d.uniq: .=.+1		" unique number from directory inode
       . = dnode+8
-fnode:				" open file entry
+fnode:				" open file entry (copied from u.ofiles)
    f.flags: .=.+1		" see below
    f.badd: .=.+1		" offset
    f.i: 0			" file i-number
diff --git a/tools/as7 b/tools/as7
index 6735b8c..a2fb1a0 100755
--- a/tools/as7
+++ b/tools/as7
@@ -342,7 +342,7 @@ sub parse_line {
 
 	print "parse_line: '$line'\n" if ($debug);
 
-	while ($line =~ s{^([a-z0-9\.]+):\s*}{}) { # labels
+	while ($line =~ s{^([A-Za-z0-9\.]+):\s*}{}) { # labels
 	    process_label($1);
 	}
 
@@ -440,7 +440,7 @@ sub parse_expression {
 	    print "\tfound >x\n" if ($debug);
 	    $syllable = ord($1)	# absolute
 	}
-	elsif ($line =~ s{^([a-z\.][a-z0-9\.]*)}{}) {
+	elsif ($line =~ s{^([A-Za-z\.][A-Za-z0-9\.]*)}{}) {
 	    my $sym = $1;
 	    print "\tsym: $sym\n" if ($debug);
 	    if (defined($Var{$sym})) {