diff --git a/scans/as.s b/scans/as.s
index 42a6c1b..8fc5957 100644
--- a/scans/as.s
+++ b/scans/as.s
@@ -208,7 +208,7 @@ proc1:
    jmp proc2
    jms bufwr
    jms copyz; buf; 64
-   lac lyrand
+   lac lvrand
    and o17700
    dac bufadd
    dac 1f
@@ -220,7 +220,7 @@ proc1:
    sys read; buf; 64
 
 proc2:
-   lac lyrand
+   lac lvrand
    and o77
    jms betwen; dm1; maxsto
    dac maxsto
@@ -256,12 +256,12 @@ bufwr: 0
    sys seek; bufadd: 0; 0
    isz maxsto
    lac bfo
-   sys write; bufp: buf; maxstp: -1
+   sys write; bufp: buf; maxsto: -1
    -1
    dac maxsto
    jmp i bufwr
 
-Xnumber: 0
+number: 0
    dac 3f
    lac d1000
    dac 2f
@@ -273,7 +273,7 @@ Xnumber: 0
    lacq
    tad o60
    dac i 8
-   iac 2b
+   lac 2b
    cll
    idiv; 10
    lacq
@@ -334,7 +334,7 @@ betwen: 0
    cma
    tad 2f
    spa
-   jmp 2f
+   jmp 1f
    lac i betwen
    dac 3f
    isz betwen
@@ -447,7 +447,7 @@ nf1:
    lac fname
    tad d4
    dac fname
-   sys open; frame: 0; 0
+   sys open; fname: 0; 0
    dac iof
    sma
    lac passno
@@ -492,20 +492,20 @@ gchar: 0
    sad o12
    skp
    jmp 1f
-   dzm comflc
+   dzm comflg
    isz lineno
 1:
    sad o42
-   dac comflc
+   dac comflg
    dac char
-   lac comflc
+   lac comflg
    sza
    jmp gchar+1
    lac char
 
 gch3:
    dac char
-   jms betwn; d0; o200
+   jms betwen; d0; o200
    cla
    tad lactab
    dac .+1
@@ -801,12 +801,12 @@ exp2:
    dac srand
    lac r+1
    dac srand+1
-   jmp expb
+   jmp exp5
 exp3:
    sad d5
    jmp exp4
    jms error; x>
-   smp skip
+   jmp skip
 exp4:
    jms pickup
    jmp i expr
@@ -924,7 +924,7 @@ o74: 074
 o76: 076
 
 namsiz: -2
-namistp: namlst
+namlstp: namlst
 fnamep: fakename
 lactab: lac .+1
 8;8;8;8;8;8;8;8
@@ -977,4 +977,4 @@ namlst:
 .=.+4
 dot:
 .=.+6
-cmflx:
\ No newline at end of file
+cmflx:
diff --git a/src/cmd/as.s b/src/cmd/as.s
index 42a6c1b..af36131 100644
--- a/src/cmd/as.s
+++ b/src/cmd/as.s
@@ -1,40 +1,41 @@
+"** 05-1-4.pdf page 32
 " as
 
-   jms init1
+   jms init1			" initialize
 
 assm1:
    lac eofflg
-   sza
-   jmp assm2
+   sza				" saw EOF?
+   jmp assm2			" no.
    lac passno
-   sza
-   jmp finis
-   jms init2
+   sza				" pass==0?
+   jmp finis			"  no, pass 2: done
+   jms init2			" pass 1: init for pass2
 
 assm2:
-   jms gchar
-   sad d4
-   jmp assm1
-   sad d5
-   jmp assm1
+   jms gchar			" get character
+   sad d4			" comma space or tab?
+   jmp assm1			"  yes, ignore
+   sad d5			" newline or ';'??
+   jmp assm1			"  yes, ignore
    lac char
-   dac savchr
+   dac savchr			" no, push back
    jms gpair
    lac rator
-   jms betwen; d1; d6
-   jmp assm3
+   jms betwen; d1; d6		" plus, minus, space comma tab or semi?
+   jmp assm3			"  no
    jms expr
    lac passno
-   sza
-   jms process
-   isz dot+1
+   sza				" pass 1?
+   jms process			"  no, process on pass 2
+   isz dot+1			" increment "."
    nop
    lac dot+1
    and o17777
-   sad dot+1
-   jmp assm1
-   jms error; >>
-   dzm dot+1
+   sad dot+1			" overflow?
+   jmp assm1			"  no
+   jms error; >>		" '>' error: past end of memory
+   dzm dot+1			" start again at zero!
    jmp assm1
 
 assm3:
@@ -43,24 +44,25 @@ assm3:
    jmp assm4
    sza
    jmp assm6
-   lac rator
-   sza
-   jmp assm6
+   lac rator			" fetch operator
+   sza				" ":"?
+   jmp assm6			"  no
    lac rand+1
-   jms betwen; dm1; d10
-   jmp assm6
-   dac name
+   jms betwen; dm1; d10		" numeric and 0..9?
+   jmp assm6			"  no
+   dac name			" yes, save as name
    tad fbxp
    dac lvrand
-   lac i lvrand
-   dac name+1
-   isz i lvrand
-   lac o146
-   dac name+2
-   dzm name+3
-   jms tlookup
+   lac i lvrand			" get fbx entry
+   dac name+1			" save in second word of name
+   isz i lvrand			" increment fbx entry
+   lac o146			" get 'f'
+   dac name+2			" save in third word of name
+   dzm name+3			" clear fourth word
+   jms tlookup			" look it up
    -1
-   dac fbflg
+"** 05-1-4.pdf page 33
+   dac fbflg			" set fbflg to -1
 assm4:
    lac rand+1
    tad d4
@@ -68,10 +70,10 @@ assm4:
    lac rator
    sza
    jmp assm5
-   lac dot
-   dac r
-   lac dot+1
-   dac r+1
+   lac dot			" load dot type
+   dac r			" save as r type
+   lac dot+1			" get dot value
+   dac r+1			" save as r value
    jmp 1f
 
 assm5:
@@ -84,87 +86,88 @@ assm5:
    lac r+1
    dac i lvrand
    lac fbflg
-   sna
-   jmp assm1
-   dzm fbflg
+   sna				" fb flag set?
+   jmp assm1			"  no
+   dzm fbflg			" clear fb flag
    dzm name+1
-   lac o142
+   lac o142			" get 'b'
    dac name+2
    jms lookup
    jmp assm4
 
 assm6:
-   jms error; x>
+   jms error; x>		" "x" error -- various errors
    jmp assm1
 
-init1: 0
+init1: 0			" init for pass 1
    lac d1
-   sys write; 1f; 2f-1f
-   dzm passno
-   lac o56040
+   sys write; 1f; 2f-1f		" output I, newline
+   dzm passno			" clear passno
+   lac o56040			" load ". "
    dac dot-4
-   lac o56056
+   lac o56056			" load ".."
    dac cmflx-4
-   lac o40040
+   lac o40040			" pad ". " and ".." names with spaces
    dac dot-3
    dac dot-2
    dac dot-1
    dac cmflx-3
    dac cmflx-2
    dac cmflx-1
-   dzm iof
+   dzm iof			" clear input fd
    jms init
    jmp i init1
 1:
-   0111012
+   0111012			" I\n
 2:
 
-init2: 0
+init2: 0			" start pass 2
    lac d1
-   dac passno
-   sys write; 1f; 2f-1f
+"** 05-1-4.pdf page 34
+   dac passno			" passno = 1
+   sys write; 1f; 2f-1f		" output II
    jms init
    lac o17
-   sys creat; 2f
+   sys creat; 2f		" create a.out
    dac bfo
-   sys open; 2f; 0
+   sys open; 2f; 0		" open a.out for read too!
    dac bfi
    dzm bufadd
-   jms copyz; buf; 64
+   jms copyz; buf; 64		" clear buffer
    jmp i init2
 1:
-   0111111;012000
+   0111111;012000		" II\n
 2:
-   0141056;0157165;0164040;040040
+   0141056;0157165;0164040;040040	" a.out
 
-init: 0
+init: 0				" common init for both passes
    lac i 017777
-   dac narg
+   dac narg			" save arg count
    lac 017777
    tad d1
-   dac fname
+   dac fname			" point to first file name
    -1
    dac eofflg
    jms ioinit
-   dzm savchr
-   dzm comflg
+   dzm savchr			" clear saved char
+   dzm comflg			" clear line comment flag
    lac d1
-   dac dot
-   dzm dot+1
-   dzm cmflx
-   lac d4096
+   dac dot			" set "." type to one??
+   dzm dot+1			" clear "." value??
+   dzm cmflx			" set ".." type to zero??
+   lac d4096			" set ".." value to 4K
    dac cmflx+1
-   dzm fbflg
+   dzm fbflg			" clear f/b flag and array
    jms copyz; fbxp: fbx; 10
-   jmp i init
+   jmp i init			" return
 
 finis:
-   lac iof
+   lac iof			" close input file
    sys close
-   jms bufwr
-   lac bfi
+   jms bufwr			" flush output buffer
+   lac bfi			" close a.out input fd
    sys close
-   lac bfo
+   lac bfo			" close a.out output fd
    sys close
    -1
    tad namsiz
@@ -175,26 +178,27 @@ finis:
    tad char
    dac 1f
    lac o17
-   sys creat; n.out
+   sys creat; n.out		" create "n.out"
    dac bfi
-   sys write; namlst; 1: 0
+   sys write; namlst; 1: 0	" write name list
    lac bfi
-   sys close
+   sys close			" close n.out
    sys exit
 
+"** 05-1-4.pdf page 35
 n.out:
-   0156056;0157165;0164040;040040
+   0156056;0157165;0164040;040040	" n.out
 
 process: 0
-   lac dot+1
+   lac dot+1			" get "." value
    dac lvrand
-   lac dot
-   sad d3
-   jmp proc4
-   sza
-   jmp proc1
+   lac dot			" get "." type??
+   sad d3			" three?
+   jmp proc4			"  no, give "." error
+   sza				" zero?
+   jmp proc1			"  no
    -1
-   tad cmflx+1
+   tad cmflx+1			" '..' - 1
    cma
    tad lvrand
    dac lvrand
@@ -203,25 +207,25 @@ proc1:
    lac lvrand
    spa
    jmp proc4
-   and o17700
-   sad bufadd
-   jmp proc2
-   jms bufwr
-   jms copyz; buf; 64
-   lac lyrand
+   and o17700			" mask to block
+   sad bufadd			" same block as buffer?
+   jmp proc2			"  yes, same block
+   jms bufwr			" different block, write out current block
+   jms copyz; buf; 64		" clear buffer
+   lac lvrand
    and o17700
    dac bufadd
    dac 1f
    lac bfi
-   sys seek; 1: 0; 0
+   sys seek; 1: 0; 0		" seek to current block from file
    spa
    jmp proc2
    lac bfi
    sys read; buf; 64
 
 proc2:
-   lac lyrand
-   and o77
+   lac lvrand
+   and o77			" get word within block
    jms betwen; dm1; maxsto
    dac maxsto
    tad bufp
@@ -231,7 +235,7 @@ proc2:
    jmp proc3
    sad d3
    jmp proc5
-   lac cmflx+1
+   lac cmflx+1			" get ".." value
    tad r+1
    dac r+1
 
@@ -243,25 +247,26 @@ proc3:
 proc4:
    jms error; .>
    lac d1
-   dac dot
-   dzm dot+1
+   dac dot		" set '.' type to 1
+"** 05-1-4.pdf page 36
+   dzm dot+1		" clear dot value
    jmp skip
 
 proc5:
    jms error; u>
    jmp proc3
 
-bufwr: 0
+bufwr: 0		" write current buffer to a.out file
    lac bfo
    sys seek; bufadd: 0; 0
    isz maxsto
    lac bfo
-   sys write; bufp: buf; maxstp: -1
+   sys write; bufp: buf; maxsto: -1
    -1
    dac maxsto
    jmp i bufwr
 
-Xnumber: 0
+number: 0		" print decimal number?
    dac 3f
    lac d1000
    dac 2f
@@ -273,7 +278,7 @@ Xnumber: 0
    lacq
    tad o60
    dac i 8
-   iac 2b
+   lac 2b
    cll
    idiv; 10
    lacq
@@ -283,96 +288,116 @@ Xnumber: 0
    jmp i number
 3: 0
 
+	" get character from buffer
+	" call with:
+	"   jms getsc; pointer_pointer
+	" where pointer_pointer contains a pointer to buffer
 getsc: 0
-   lac i getsc
-   dac sctalp
-   isz getsc
-   lac i sctalp
-   dac sctal
-   add o400000
-   dac i sctalp
-   ral
-   lac i sctal
-   szl
-   lrss 9
-   and o177
-   jmp i getsc
+   lac i getsc			" get pointer pointer
+   dac sctalp			" save
+   isz getsc			" skip pointer pointer
+   lac i sctalp			" fetch pointer
+   dac sctal			" save
+   add o400000			" toggle high bit of pointer
+   dac i sctalp			" save pointer back
+   ral				" rotate high bit into link reg
+   lac i sctal			" load word from buffer
+   szl				" skip if link zero
+   lrss 9			"  link set: get high char from word
+   and o177			" strip to 7 bits
+   jmp i getsc			" return
 
+	" save characters: word after call is addr of pointer, -count pair
+	" high bit in pointer used to indicate high or low byte next?
 putsc: 0
-   and o177
-   lmq
-   lac i putsc
-   dac sctalp
-   isz putsc
-   lac i sctalp
-   dac sctal
-   add o400000
-   dac i sctalp
-   sma cla
-   jmp 1f
-   llss 27
-   dac i sctal
-   lrss 9
-   jmp i putsc
+   and o177			" strip character to 7 bits
+   lmq				" save in MQ
+   lac i putsc			" get address of pointer
+   dac sctalp			" save
+   isz putsc			" skip over pointer to pointer
+"** 05-1-4.pdf page 37
+   lac i sctalp			" get pointer
+   dac sctal			" save
+   add o400000			" toggle sign bit by adding -0
+   dac i sctalp			" save pointer
+   sma cla			" skip if minus & clear AC
+   jmp 1f			"  AC positive
+   llss 27			" get char in high 9 bits, zero in low
+   dac i sctal			" store word
+   lrss 9			" shift char back down
+   jmp i putsc			" return
 
 1:
-   lac i sctal
-   omq
-   dac i sctal
-   lacq
-   jmp i putsc
+   lac i sctal			" load target word
+   omq				" or in char from MQ
+   dac i sctal			" save word back
+   lacq				" restore character
+   jmp i putsc			" return
 
 sctalp: 0
 sctal: 0
 
+	" test if between two values (low,high]
+	" call with value in AC
+	"    jms betwen; lowptr; highptr
+	" skip returns if AC in range
+	" AC returned unmodified
+	" NOTE!
+	" the test appears to be non-inclusive
+	" on the low side, and inclusive on the high side
+
 betwen: 0
-   dac 2f
-   lac i betwen
-   dac 3f
-   isz betwen
-   lac i 3f
+   dac 2f			" save value to test
+   lac i betwen			" load range start addr
+   dac 3f			" save
+   isz betwen			" increment return PC
+   lac i 3f			" load range start
+   cma				" complement
+   tad 2f			" AC = AC - start - 1
+   spa				" still positive?
+   jmp 1f			"  no
+   lac i betwen			" load range end addr
+   dac 3f			" save
+   isz betwen			" skip range high on return
+   lac i 3f			" load range high
    cma
-   tad 2f
-   spa
-   jmp 2f
-   lac i betwen
-   dac 3f
-   isz betwen
-   lac i 3f
-   cma
-   tad d1
-   tad 2f
-   spa
+   tad d1			" negate AC (~AC + 1)
+   tad 2f			" add test value
+   spa				" if not positive, don't skip on return!!
 1:
-   isz betwen
-   lac 2f
-   jmp i betwen
+   isz betwen			" discard "high" (or skip return)!
+   lac 2f			" restore AC
+   jmp i betwen			" return
 2: 0
 3: 0
 
+	" zero a block of memory
+	" call with:
+	"   jms copyz; ptr; count
 copyz: 0
    -1
-   tad i copyz
-   dac 8
-   isz copyz
-   lac i copyz
-   cma
+   tad i copyz			" get address-1
+   dac 8			" store in first "index register"
+   isz copyz			" skip over address
+   lac i copyz			" load count
+   cma				" get -count
    tad d1
-   dac 2f
-   isz copyz
+   dac 2f			" save
+   isz copyz			" skip over count
 1:
-   dzm i 8
-   isz 2f
-   jmp 1b
-   jmp i copyz
+   dzm i 8			" increment index, clear word
+   isz 2f			" increment count, skip if done
+   jmp 1b			"  not done, loop
+   jmp i copyz			" done: return
+"** 05-1-4.pdf page 38
 2: 0
 
 error: 0
-   lac passno
-   sza
-   jmp 1f
-   isz error
-   jmp i error
+   lac passno			" get pass number
+   sza				" pass one?
+   jmp 1f			"  no, pass two
+   isz error			" pass one: skip error char
+   jmp i error			" return
 1:
    -1
    tad mesp
@@ -385,7 +410,7 @@ error: 0
    sad d5
    jmp 1f
    lac savchr
-   sad o12
+   sad o12				
    jmp 1f
    lac lineno
    jmp 2f
@@ -407,330 +432,337 @@ error: 0
    jmp i error
 
 skip:
-   lac rator
-   sad d5
-   jmp assm1
+   lac rator			" get operator
+   sad d5			" EOL?
+   jmp assm1			"  yes, start from top
 1:
-   jms gchar
-   sad d5
-   jmp assm1
+   jms gchar			" loop until ';' or NL seen
+   sad d5			" EOL?
+   jmp assm1			"  yes, start from top
    jmp 1b
 
 ioinit: 0
-   jms copyz; iobuf; 64
+   jms copyz; iobuf; 64		" clear iobuf
    lac iof
-   sys read; iobufp: iobuf; 64
-   sna
-   jms nextfil
-   lac iobufp
-   dac tal
-   -129
-   dac talc
-   jmp i ioinit
+   sys read; iobufp: iobuf; 64	" read from input
+   sna				" EOF?
+   jms nextfil			"  yes, skip to next file
+   lac iobufp			" load iobuf pointer
+   dac tal			" save
+   -129				" get -bytecount-1
+   dac talc			" save as count
+"** 05-1-4.pdf page 39
+   jmp i ioinit			" return
 
-nextfil: 0
+nextfil: 0			" advance to next file
    lac d1
-   dac lineno
-   lac iof
-   sza
-   sys close
+   dac lineno			" reset lineno to 1
+   lac iof			" load input fd
+   sza				" zero?
+   sys close			"  no: close
 nf1:
-   lac narg
-   sad d4
-   skp
-   jmp 1f
-   dzm eofflg
-   jmp i nextfil
+   lac narg			" load arg count
+   sad d4			" ==4? (done)
+   skp				"  yes, skip
+   jmp 1f			"   no
+   dzm eofflg			" flag eof (set to zero)
+   jmp i nextfil		" return
 1:
-   tad dm4
-   dac narg
-   lac fname
-   tad d4
-   dac fname
-   sys open; frame: 0; 0
-   dac iof
-   sma
-   lac passno
-   sna
-   jmp nextfil i
-   lac fname
-   dac 1f
+   tad dm4			" subtract 4
+   dac narg			" store narg
+   lac fname			" get fname pointer
+   tad d4			" subtract 4
+   dac fname			" save fname
+   sys open; fname: 0; 0	" open fname
+   dac iof			" save fd
+   sma				" open ok?
+   lac passno			"  yes, load pass number
+   sna				"   open failed: skip or open ok, pass 2
+   jmp nextfil i		"    pass 1, open OK, return.
+   lac fname			" load filename pointer
+   dac 1f			" save for write
+   lac d1			" stdout
+   sys write; 1; 0; 4		" output filename
+   lac iof			" load fd
+   sma				" open ok?
+   jmp 1f			"  yes, continue
    lac d1
-   sys write; 1; 0; 4
-   lac iof
-   sma
-   jmp 1f
-   lac d1
-   sys write; emes; 2
-   sys exit
+   sys write; emes; 2		" output "? \n"
+   sys exit			" quit.
 1:
    lac d1
-   sys write; emes+1; 1
-   jmp i nextfil
+   sys write; emes+1; 1		" output newline after filename
+   jmp i nextfil		" return
 emes:
-   040077;012000
+   040077;012000		" question mark, space, newline
 
 gchar: 0
-   lac savchr
-   dzm savchr
-   sza
-   jmp gch3
-   lac eofflg
-   sza
-   jmp 1f
-   lac o12
-   jmp gch3
+   lac savchr			" load saved char
+   dzm savchr			" clear saved char
+   sza				" was there a saved char?
+   jmp gch3			"  yes, process it
+   lac eofflg			" no: get eof flag
+   sza				" seen eof (zero if true)
+   jmp 1f			"  no.
+   lac o12			" yes: get NL
+   jmp gch3			" process it
 1:
-   isz talc
-   skp
-   jms ioinit
-   jms getsc; tal
-   sna
-   jmp gchar+1
-   sad o177
-   jmp gchar+1
-   sad o12
-   skp
-   jmp 1f
-   dzm comflc
-   isz lineno
+   isz talc			" increment (negative count): is it zero?
+   skp				"  non-zero: skip
+   jms ioinit			"   count was zero: call ioinit
+   jms getsc; tal		" fetch character
+   sna				" is char non-zero?
+   jmp gchar+1			"  no: char is zero, get another
+"** 05-1-4.pdf page 40
+   sad o177			" is char 0177
+   jmp gchar+1			"  yes, ignore it
+   sad o12			" is char newline?
+   skp				"  yes
+   jmp 1f			"   no
+   dzm comflg			" saw newline: clear comflg
+   isz lineno			" increment line number
 1:
-   sad o42
-   dac comflc
-   dac char
-   lac comflc
-   sza
-   jmp gchar+1
-   lac char
+   sad o42			" is char '"'?
+   dac comflg			"  yes, set comflg
+   dac char			" save char
+   lac comflg			" load comflg
+   sza				" comflg clear?
+   jmp gchar+1			"  no: ignore reset of line
+   lac char			" get char
 
 gch3:
-   dac char
-   jms betwn; d0; o200
-   cla
-   tad lactab
-   dac .+1
-   lac 0
-   jmp i gchar
+   dac char			" save char in char
+   jms betwen; d0; o200		" legal char?
+   cla				"  no, clear
+   tad lactab			" add to "lac labtab+1"
+   dac .+1			" save as next instruction
+   lac 0			" get character class in AC
+   jmp i gchar			" return
 
 gsymb: 0
-   jms gchar
-   dac rator
-   tad jmpsw1
-   dac 1f
-   lac char
-   sad o74
-   jmp lqot
-   dac namc
-   jms gchar
-   lac char
-   sad o76
-   jmp rqot
-   dac savchr
-   lac namc
-   dac char
+   jms gchar			" get char
+   dac rator			" save class
+   tad jmpsw1			" add table base instruction
+   dac 1f			" save for later
+   lac char			" what was it?
+   sad o74			" '<'??
+   jmp lqot			"  yes: process as "left quote"
+   dac namc			" no, save as namc
+   jms gchar			" get another
+   lac char			" what was it?
+   sad o76			" '>'?
+   jmp rqot			"  yes: process "right quote"
+   dac savchr			" no: save as savchr
+   lac namc			" restore first char
+   dac char			" resave as "char"
 1:
-   jmp 0
+   jmp 0			" jmpsw1[0] + class
+jmpsw1:				" indexed by character class
+   jmp .+1			" base instruction (added to class)
+   jmp i gsymb			" 0: ":" return
+   jmp i gsymb			" 1: "=" return
+   jmp i gsymb			" 2: "+" return
+   jmp i gsymb			" 3: "-" return
+   jmp gs1			" 4: comma, space, tab
+   jmp i gsymb			" 5: EOL (semi, newline)
+   jmp gs2			" 6: dot, star, letter
+   jmp gs3			" 7: digits
 
-jmpsw1:
-   jmp .+1
-   jmp i gsymb
-   jmp i gsymb
-   jmp i gsymb
-   jmp i gsymb
-   jmp gs1
-   jmp i gsymb
-   jmp gs2
-   jmp gs3
-
-badchr:
-   jms error; g>
+badchr:				" here with bad char (class 8)
+   jms error; g>		" error "g"
 1:
-   jms gchar
+   jms gchar			" discard until newline
    lac char
    sad o12
+"** 05-1-4.pdf page 41
    skp
    jmp 1b
-   dac savchr
-   jmp gsymb+1
+   dac savchr			" push newline back
+   jmp gsymb+1			" restart gsymb
 
-lqot:
-   jms gchar
+lqot:				" left quote (<)
+   jms gchar			" get another char
    lac o40
-   dac savchr
-   lac char
-   alss 9
-   jmp 1f
+   dac savchr			" put a space in savchr
+   lac char			" get quoted character
+   alss 9			" shift up 9 bits
+   jmp 1f			" join with right quote
 
-rqot:
-   lac namc
+rqot:				" right quote (>)
+   lac namc			" get previous(?) char
 1:
    dac rand+1
    lac d7
    dac rator
    jmp i gsymb
 
-gs1:
-   jms gchar
-   sad d4
-   jmp gs1
-   lac char
+gs1:				" here with space, tab, comma
+   jms gchar			" get another char
+   sad d4			" another space?
+   jmp gs1			"  yes, loop
+   lac char			" no, save for later
    dac savchr
-   jmp i gsymb
+   jmp i gsymb			" return
 
-gs2:
-   lac namep
-   dac tal1
-   -7
-   dac tal1c
-   lac char
-   jms putsc; tal1
+gs2:				" here with dot, star, letter
+   lac namep			" load name buffer pointer
+   dac tal1			" save in temp pointer
+   -7				" load negative char count
+   dac tal1c			" save as temp counter
+   lac char			" restore char
+   jms putsc; tal1		" save it in name buffer
 
-gnam1:
+gnam1:				" here to collect a name
    jms gchar
-   jms betwen; d5; d8
-   jmp gnam3
+   jms betwen; d5; d8		" alphanumeric?
+   jmp gnam3			"  no, done
    lac char
    jms putsc; tal1
    isz tal1c
    jmp gnam1
 
-gnam2:
-   jms gchar
-   jms betwen; d5; d8
-   skp
-   jmp gnam2
+gnam2:				" here when 8 characters read, eat the rest
+   jms gchar			" next char
+   jms betwen; d5; d8		" alphanumeric?
+   skp				"  no
+   jmp gnam2			"   yes, loop
    lac char
-   dac savchr
-   jms lookup
-   jmp i gsymb
+   dac savchr			" push last char back
+   jms lookup			" look up symbol
+   jmp i gsymb			" return
 
-gnam3:
-   lac char
+gnam3:				" here before 8 characters
+   lac char			" push last char back
    dac savchr
 1:
-   lac o40
+   lac o40			" pad to 8 with spaces
+"** 05-1-4.pdf page 42
    jms putsc; tal1
    isz tal1c
    jmp 1b
    jms lookup
    jmp i gsymb
 
-gs3:
-   dzm rand+1
+gs3:				" here with digit
+   dzm rand+1			" clear number
    lac char
-   sad o60
-   jmp 1f
-   lac d10
+   sad o60			" zero?
+   jmp 1f			"  yes
+   lac d10			" no: process as decimal
    jmp 2f
 1:
-   lac d8
+   lac d8			" leading zero: process as octal
 2:
-   dac num2
+   dac num2			" save radix
 
 num1:
-   lac rand+1
-   cll
-   mul
-num2: 0
-   lacq
-   tad char
-   tad dm48
-   dac rand+1
-   jms gchar
-   sad d7
-   jmp num1
-   lac char
-   dac savchr
-   lac rand+1
-   jms betwen; dm1; d10
-   jmp i gsymb
+   lac rand+1			" get number
+   cll				" clear link
+   mul				" mutiply by radix
+num2: 0				" (radix stored here)
+   lacq				" get multiply result
+   tad char			" add char
+   tad dm48			" subtract '0'
+   dac rand+1			" save
+   jms gchar			" get another
+   sad d7			" digit?
+   jmp num1			"  yes: process
+   lac char			" no: get it
+   dac savchr			" push back
+   lac rand+1			" get number
+   jms betwen; dm1; d10		" between 0..9?
+   jmp i gsymb			"  no, return
    dac name
-   tad fbxp
-   dac name+1
-   lac i name+1
-   dac name+1
-   lac savchr
-   sad o146
-   jmp 1f
-   sad o142
-   skp
-   jmp i gsymb
-   dzm name+1
-1:
-   dac name+2
-   dzm name+3
-   lac d6
-   dac rator
-   jms lookup
-   dzm savchr
+   tad fbxp			" make index into "fbx" array
+   dac name+1			" ???save??? (crushed below)
+   lac i name+1			" fetch fbx array entry
+   dac name+1			" save fbx count in name
+   lac savchr			" get break character
+   sad o146			" was it 'f'?
+   jmp 1f			"  yes
+   sad o142			" 'b'?
+   skp				"  yes
+   jmp i gsymb			"   not f or b, return
+   dzm name+1			" 'b': clear loaded fbx entry????
+1:				" here with DIGITS[fb]
+   dac name+2			" save f/b in third word of name
+   dzm name+3			" clear last word of name
+   lac d6			" class 6: alpha, dot star
+   dac rator			" save as (ope)rator
+   jms lookup			" lookup (create) symbol entry????
+   dzm savchr			" clear saved char
    jmp i gsymb
 
+	" symbol lookup/creation
+	" tlookup doesn't create new entries???
 tlookup: 0
       jmp 1f
 lookup: 0
-      dzm tlookup
+      dzm tlookup		" NOT a tlookup call
 1:
+"** 05-1-4.pdf page 43
    -1
    tad namlstp
-   dac 8
+   dac 8			" get namelist ptr in index reg
    lac namsiz
-   dac namc
+   dac namc			" negative namelist size in namc
 lu1:
-   lac i 8
-   sad name
-   jmp 1f
-   lac d5
+   lac i 8			" get first word of namelist entry
+   sad name			" match name?
+   jmp 1f			"  yes
+   lac d5			" no, skip next 5 words
 lu2:
    tad 8
    dac 8
-   isz namc
-   jmp lu1
-      lac tlookup
-      sna
-      jmp 2f
+   isz namc			" at end of list?
+   jmp lu1			"  no, keep going
+      lac tlookup		" yes, reached end
+      sna			" was tlookup?
+      jmp 2f			"  no, was lookup
       lac fnamep
-      dac rand+1
-      jmp i tlookup
+      dac rand+1		" set rand+1 (value?) to fakename
+      jmp i tlookup		" return
 2:
-   lac name
-   dac i 8
+   lac name			" make new entry
+   dac i 8			" save word one of name
    lac 8
    dac rand+1
    lac name+1
-   dac i 8
+   dac i 8			" save word two
    lac name+2
-   dac i 8
+   dac i 8			" save word three
    lac name+3
-   dac i 8
+   dac i 8			" save word four
    lac d3
-   dac i 8
-   dzm i 8
-   -1
+   dac i 8			" set type(?) to three
+   dzm i 8			" clear value??
+   -1				" decrement namsiz
    tad namsiz
    dac namsiz
-   jmp i lookup
-1:
+   jmp i lookup			" return
+1:				" here when first word matched
    lac i 8
-   sad name+1
-   jmp 1f
-   lac d4
+   sad name+1			" check second word
+   jmp 1f			"  matched, keep going
+   lac d4			" no match: skip ahead four words
    jmp lu2
 1:
    lac i 8
-   sad name+2
-   jmp 1f
-   lac d3
+   sad name+2			" does third word match?
+   jmp 1f			"  yes, keep going
+   lac d3			" no, skip ahead three words
    jmp lu2
 1:
    lac i 8
-   sad name+3
-   jmp 1f
-   lac d2
+   sad name+3			" final word match?
+   jmp 1f			"  yes
+   lac d2			" no, skip two words
    jmp lu2
-1:
+1:				" name matched
    -3
-   tad 8
-   dac rand+1
+   tad 8			" get next word minus three
+   dac rand+1			" return as value
+"** 05-1-4.pdf page 44
       lac tlookup
       sza
       jmp i tlookup
@@ -739,37 +771,37 @@ namep: name
 
 gpair: 0
    jms gsymb
-   lac rator
-   sad d4
-   jmp gpair+1
-   jms betwen; dm1; d6
-   jmp gp1
+   lac rator			" get operator
+   sad d4			" space tab or comma?
+   jmp gpair+1			"  yes, get another
+   jms betwen; dm1; d6		" anything but a digit?
+   jmp gp1			"  no-- a digit
    dzm rand
    dzm rand+1
    jmp i gpair
-gp1:
+gp1:				" here with digit
    sad d7
    lac d4
    tad dm4
    dac rand
    jms gsymb
    lac rator
-   sad d4
-   jmp gp2
-   jms betwen; dm1; d6
-   skp
-   jmp i gpair
-   jms error; x>
+   sad d4			" whitespace?
+   jmp gp2			"  yes
+   jms betwen; dm1; d6		" anything but digit?
+   skp				"  no, a digit
+   jmp i gpair			"   yes, return
+   jms error; x>		" here with digit: give 'x' error
    jmp skip
-gp2:
-   jms gchar
-   jms betwen; d5; d8
-   jmp gp3
-   lac char
+gp2:				" here after whitespace
+   jms gchar			" get next char
+   jms betwen; d5; d8		" alphanumeric?
+   jmp gp3			"  no
+   lac char			" yes, push back
    dac savchr
    jmp i gpair
 gp3:
-   lac char
+   lac char			" push back break char
    dac savchr
    jms gsymb
    jmp i gpair
@@ -785,14 +817,15 @@ exp5:
    dac r+1
 exp1:
    lac rator
-   jms betwen; d1; d5
-   jmp exp3
+   jms betwen; d1; d5		" plus, minus, comma, space, tab or comma?
+   jmp exp3			"  no
    dac orator
    jms gpair
    jms grand
-   lac orator
-   sad d4
-   jmp exp2
+   lac orator			" get operator back
+   sad d4			" comma space or tab?
+"** 05-1-4.pdf page 45
+   jmp exp2			"  no
    jms oper; rand
    jmp exp1
 exp2:
@@ -801,12 +834,12 @@ exp2:
    dac srand
    lac r+1
    dac srand+1
-   jmp expb
+   jmp exp5
 exp3:
    sad d5
    jmp exp4
    jms error; x>
-   smp skip
+   jmp skip
 exp4:
    jms pickup
    jmp i expr
@@ -853,6 +886,7 @@ opsw:
    jmp .-1
    jmp oplus
    jmp ominus
+"** 05-1-4.pdf page 46
    tad r
    dac r
    lac r+1
@@ -911,9 +945,10 @@ dm4: -4
 o200: 0200
 o42: 042
 o142: 0142
-o40040: 040040
-o56056: 056056
-o56040: 056040
+o40040: 040040		" space, space
+o56056: 056056		" ".."
+o56040: 056040		" ". "
+"** 05-1-4.pdf page 47
 o146: 0146
 o17777: 017777
 d1000: 1000
@@ -924,22 +959,22 @@ o74: 074
 o76: 076
 
 namsiz: -2
-namistp: namlst
+namlstp: namlst
 fnamep: fakename
-lactab: lac .+1
+lactab: lac .+1		" character class table (8 unless noted)
 8;8;8;8;8;8;8;8
-8;4;5;8;8;8;8;8
+8;4;5;8;8;8;8;8		" TAB=4 NL=5
 8;8;8;8;8;8;8;8
 8;8;8;8;8;8;8;8
-4;8;8;8;8;8;8;8
-8;8;6;2;4;3;6;8
-7;7;7;7;7;7;7;7
-7;7;0;5;8;1;8;8
-8;6;6;6;6;6;6;6
+4;8;8;8;8;8;8;8		" SP=4
+8;8;6;2;4;3;6;8		" *=6 +=2 ,=4 -=3 .=6
+7;7;7;7;7;7;7;7		" digits=7
+7;7;0;5;8;1;8;8		" :=0 ;=5 ==1
+8;6;6;6;6;6;6;6		" A-Z=6
 6;6;6;6;6;6;6;6
 6;6;6;6;6;6;6;6
 6;6;6;8;8;8;8;8
-8;6;6;6;6;6;6;6
+8;6;6;6;6;6;6;6		" a-z=6
 6;6;6;6;6;6;6;6
 6;6;6;6;6;6;6;6
 6;6;6;8;8;8;8;8
@@ -965,16 +1000,23 @@ r: .=.+2
 name: .=.+4
 buf: .=.+64
 iobuf: .=.+64
-fbx: .=.+10
+fbx: .=.+10			" forward/backward pointers?
 mes: .=.+20
 iof: .=.+1
 bfi: .=.+1
 bfo: .=.+1
 lineno: .=.+1
 
-fakename: .=.+6
+fakename: .=.+6	" dummy entry returned by tlookup??
 namlst:
 .=.+4
-dot:
+dot:		" dot type, value
 .=.+6
-cmflx:
\ No newline at end of file
+cmflx:		" dotdot type, value
+
+		" first four words of name list are symbol (space padded)
+		" next word is type??
+		"   0: initial dotdot type
+		"   1: initial dot type
+		"   3: set by "lookup"
+		" last word is value??
\ No newline at end of file
diff --git a/src/sys/sop.s b/src/sys/sop.s
index 124ee9d..047a1ba 100644
--- a/src/sys/sop.s
+++ b/src/sys/sop.s
@@ -25,7 +25,7 @@ sma = 0740100			" OPR: skip on minus AC
 sza = 0740200			" OPR: skip on zero AC
 snl = 0740400			" OPR: skip on non-zero link
 skp = 0741000			" OPR: skip unconditionally
-sna = 0741200			" OPR: skip on negative AC
+sna = 0741200			" OPR: skip on non-zero AC
 szl = 0741400			" OPR: skip on zero link
 rtl = 0742010			" OPR: rotate two left
 rtr = 0742020			" OPR: rotate two right
diff --git a/tools/as7 b/tools/as7
index 943121b..e9ecdda 100755
--- a/tools/as7
+++ b/tools/as7
@@ -298,14 +298,14 @@ sub process_label {
 # (: and ; can appear in char literals)
 # handles multiple ';' separated words per line
 sub parse_line {
-    # Lose any leading whitespace
-    $line =~ s{^\s*}{};
-
     while (1) {
 	$line_error = ' ';	# clear listing error indicator
 
 	return if ($line eq '' || $line =~ m{^"}); # empty or comment: quit
 
+	# Lose any leading whitespace
+	$line =~ s{^\s*}{};
+
 	print "parse_line: '$line'\n" if ($debug);
 
 	while ($line =~ s{^([a-z0-9\.]+):\s*}{}) { # labels