From 66a81682287abb60879a6d4caf276cd6e7b02d4b Mon Sep 17 00:00:00 2001
From: Phil Budne <phil@ultimate.com>
Date: Tue, 8 Mar 2016 00:34:35 -0500
Subject: [PATCH 1/4] as.s starting to work!  Add ops.s replaced "sys write; 1;
 0; 4" with "sys write; 1: 0; 4"   In the scan it REALLY looks like three
 semis, but that makes NO sense!

---
 src/cmd/as.s  |   8 ++--
 src/cmd/ops.s | 123 ++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 127 insertions(+), 4 deletions(-)
 create mode 100644 src/cmd/ops.s

diff --git a/src/cmd/as.s b/src/cmd/as.s
index e36ea9e..e410dbf 100644
--- a/src/cmd/as.s
+++ b/src/cmd/as.s
@@ -125,7 +125,7 @@ init2: 0			" start pass 2
    lac d1
 "** 05-1-4.pdf page 34
    dac passno			" passno = 1
-   sys write; 1f; 2f-1f		" output II
+   sys write; 1f; 2f-1f		" output II\n
    jms init
    lac o17
    sys creat; 2f		" create a.out
@@ -479,9 +479,9 @@ nf1:
    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 passno			"  yes: load pass number
+   sna				" no: 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
diff --git a/src/cmd/ops.s b/src/cmd/ops.s
new file mode 100644
index 0000000..b7a3d50
--- /dev/null
+++ b/src/cmd/ops.s
@@ -0,0 +1,123 @@
+" ops and system calls from as7; as.s has no initial symbol table
+" so this needs to be included in any assembly of user programs
+
+" "sys" has it's own sop.s which includes I/O instructions, but lacks
+" system call definitions, and lacks some instructions used in
+" commands but not in the kernel, so it can't have been the file used
+" for user assemblies.
+
+save   = 1		" saves core dump & user area!
+getuid = 2
+open   = 3
+read   = 4
+write  = 5
+creat  = 6
+seek   = 7
+tell   = 8
+close  = 9
+link   = 10
+unlink = 11
+setuid = 12
+rename = 13
+exit   = 14
+time   = 15
+intrp  = 16
+chdir  = 17
+chmod  = 18
+chown  = 19
+" 20 removed
+sysloc = 21		" return system addresses
+" 22 removed
+capt   = 23		" capture display?
+rele   = 24		" release display?
+status = 25		" "stat"
+smes   = 27
+rmes   = 28
+fork   = 29
+
+" List of instruction names and machine code values
+" These come from https://raw.githubusercontent.com/simh/
+
+sys    = 0020000		" "cal i" instruction (trap indirect thru 020)
+i      = 0020000		" indirect bit
+
+" memory reference instructions
+dac    = 0040000		" deposit AC
+jms    = 0100000		" jump to subroutine
+dzm    = 0140000		" deposit zero in memory
+lac    = 0200000		" load AC
+xor    = 0240000		" exclusive or
+add    = 0300000		" one's complement add
+tad    = 0340000		" two's complement add
+xct    = 0400000		" execute
+isz    = 0440000		" increment and skip if zero
+and    = 0500000		" AND with contents of Y
+sad    = 0540000		" skip if AC different from content of Y
+jmp    = 0600000		" jump to Y
+
+" Type 177 Extended Arithmetic Element (EAE)
+eae    = 0640000		" base instruction (nop)
+osc    = 0640001		" OR SC into AC
+omq    = 0640002		" OR MQ into AC
+cmq    = 0640004		" Complement MQ
+div    = 0640323		" divide
+norm   = 0640444		" normalize unsigned
+lls    = 0640600		" long left shift
+als    = 0640700		" AC shift
+lrs    = 0640500		" long right shift
+lacs   = 0641001		" load AC with SC
+lacq   = 0641002		" load AC with MQ
+abs    = 0644000		" absolute value
+divs   = 0644323		" divide signed
+
+clq    = 0650000		" clear MQ
+frdiv  = 0650323		" fractional divide
+lmq    = 0652000		" load MQ from AC
+mul    = 0653122		" multiply
+idiv   = 0653323		" integer divide
+idivs  = 0657323		" integer divide signed
+frdivs = 0654323		" fractional divide signed
+muls   = 0657122		" multiply signed
+
+norms  = 0660444		" normalize signed
+gsm    = 0664000		" get sign and magnitude
+lrss   = 0660500		" long right shift signed
+llss   = 0660600		" long left shift signed
+alss   = 0660700		" AC left shift signed
+
+" Operate Instructions
+
+" Group 1 (OPR 1) instructions
+opr    = 0740000		" base operate instruction (nop)
+nop    = 0740000
+cma    = 0740001		" complement accumulator
+cml    = 0740002		" complement link
+oas    = 0740004		" inclusive or accumulator switches
+ral    = 0740010		" rotate (ac link) left
+rar    = 0740020		" rotate (ac link) right
+hlt    = 0740040		" HALT
+xx     = 0740040
+sma    = 0740100		" skip on minus accumulator
+sza    = 0740200		" skip on zero accumulator
+snl    = 0740400		" skip on non-zero link
+
+skp    = 0741000		" unconditional skip
+spa    = 0741100		" skip on positive accumulator
+sna    = 0741200		" skip on negative accumulator
+szl    = 0741400		" skip on zero link
+
+rtl    = 0742010		" rotate two left (ral*2)
+rtr    = 0742020		" rotate two right (rar*2)
+
+cll    = 0744000		" clear link
+stl    = 0744002		" set link
+rcl    = 0744010		" clear link rotate left
+rcr    = 0744020		" clear link rotate right
+
+cla    = 0750000		" clear accumulator
+clc    = 0750001		" clear and complement acc
+las    = 0750004		" load acc from switches
+glk    = 0750010		" get link
+
+" Group 2 operate
+law    = 0760000		" load accumulator with (instruction)

From 03d5e49ae91c6a972c68d38622c2b4654fe0983f Mon Sep 17 00:00:00 2001
From: Phil Budne <phil@ultimate.com>
Date: Tue, 8 Mar 2016 11:49:18 -0500
Subject: [PATCH 2/4] sys comments for rmes/smes calls, process table (user
 list) words noticed "exit" call falls into "rmes" call!!!

---
 src/sys/s1.s | 10 ++++-----
 src/sys/s2.s |  2 +-
 src/sys/s3.s | 63 ++++++++++++++++++++++++++++++----------------------
 src/sys/s7.s |  2 +-
 src/sys/s8.s |  7 ++++--
 5 files changed, 48 insertions(+), 36 deletions(-)

diff --git a/src/sys/s1.s b/src/sys/s1.s
index f50088c..6b71282 100644
--- a/src/sys/s1.s
+++ b/src/sys/s1.s
@@ -86,7 +86,7 @@ swap: 0
    jms lookfor; 1 " in/ready
       skp
    jmp 1b			" loop until a process becomes ready
-   dzm maxquant			" here with in/ready (self?)
+   dzm maxquant			" in/ready (self?): come back next tick!
    jmp 3f
 1:				" here with out/ready process
    dac 9f+t			" save process pointer (swapped out) in t0
@@ -97,7 +97,7 @@ swap: 0
    jmp 2f
 1:
    lac swap
-   dac u.swapret		" return to scheduler when swapped back
+   dac u.swapret		" return to caller when swapped back
    iof
    lac o200000			" change status to swapped out
    tad u.ulistp i
@@ -105,13 +105,13 @@ swap: 0
    ion
    jms dskswap; 07000		" swap process out
    lac u.dspbuf
-   sna
-   jmp 2f
+   sna				" process using display??
+   jmp 2f			"  no
    law dspbuf
    jms movdsp
 2:
    iof				" disable interrupts
-   lac o600000			" change status (1->7?)
+   lac o600000			" change status (1->7?????)
    tad 9f+t i
    dac 9f+t i
    ion				" enable interrupts
diff --git a/src/sys/s2.s b/src/sys/s2.s
index 4006ed5..64d6f93 100644
--- a/src/sys/s2.s
+++ b/src/sys/s2.s
@@ -284,7 +284,7 @@ open1:				" common exit for open/creat
    jmp 1f			"  no
    iof				" yes: disable interrupts
    lac ii			" get i number
-   tad swr			" get read routine table addr
+   tad swr			" add to base instruction
    dac .+1
    jmp .. i			" dispatch to read routine
 1:
diff --git a/src/sys/s3.s b/src/sys/s3.s
index 45be20e..baec05c 100644
--- a/src/sys/s3.s
+++ b/src/sys/s3.s
@@ -1,7 +1,7 @@
 "** 01-s1.pdf page 14
 " s3
 
-	" search for user (process)
+	" search for user (process) table entry
 	" call:
 	"   jms searchu; worker_routine_addr
 	" worker called with copy of a process table entry in "lu"
@@ -113,36 +113,44 @@ badcal:				" bad (unimplemented) system call
    isz u.ulistp
    dzm u.ulistp i		" clear pid in process table
    jms swap			" find a new process to run
+	" exit falls into "rmes" !!!
 
+	" rmes system call
+	"   sys smes
+	" returns with message delivered, or error if process does not exit
+	" AC/ sending pid
+	" MQ/ message
 .rmes:
    jms awake
-   lac o100000
+   lac o100000			" mark this process to "not ready"
    tad u.ulistp i
    dac u.ulistp i
    law 2
    tad u.ulistp
-   dac 9f+t
+   dac 9f+t			" pointer to msg status in proc table
    -1
-   dac 9f+t i
-   jms swap
+   dac 9f+t i			" set to -1 (waiting for message)
+   jms swap			" switch processes
    law 2
    tad u.ulistp
    dac 9f+t
-   lac 9f+t i
-   cma
-   dac u.ac
-   dzm 9f+t i
+   lac 9f+t i			" get msg status word
+   cma				" complement (get sender pid)
+   dac u.ac			" return in user AC
+   dzm 9f+t i			" clear status word
    isz 9f+t
-   lac 9f+t i
-   dac u.mq
-   dzm 9f+t i
+   lac 9f+t i			" get message
+   dac u.mq			" return in user MQ
+   dzm 9f+t i			" clear message
    jmp sysexit
 t = t+1
 
 "** 01-s1.pdf page 16
 	" smes system call
 	" AC/ pid
+	" MQ/ message
 	"   sys smes
+	" returns with message delivered, or error if process does not exit
 .smes:
    lac u.ac			" get pid from user AC
    sna spa			" >0?
@@ -158,10 +166,10 @@ t = t+1
    sad u.ac			" match?
    skp				"  yes
    jmp 1b i			"   no
-   lac lu+2			" get mailbox
+   lac lu+2			" get mailbox status
    sad dm1			" -1?
    jmp 1f			"  yes
-   lac o100000			" no: increment process status
+   lac o100000			" no: bump our process status (to notready?)
    tad u.ulistp i
    dac u.ulistp i
    law 2
@@ -178,35 +186,36 @@ t = t+1
 1:
    -3
    tad 8
-   dac 9f+t
-   lac o700000
+   dac 9f+t			" pointer to dest process ulist entry
+   lac o700000			" complement process status? marks ready??
    tad 9f+t i
    dac 9f+t i
    isz 9f+t
-   isz 9f+t
-   lac u.pid
-   cma
-   dac 9f+t i
-   isz 9f+t
-   lac u.mq
-   dac 9f+t i
+   isz 9f+t			" point to mailbox word?
+   lac u.pid			" get our pid
+   cma				" complement
+   dac 9f+t i			" store in mailbox??
+   isz 9f+t			" advance to next word
+   lac u.mq			" get user MQ
+   dac 9f+t i			" save as message
    jmp okexit
 t = t+1
 
+	" wake up process hanging on rmes for current process??
 awake: 0
    jms searchu; 1f
    jmp awake i
 1: 0				" searchu worker
    lac u.pid			" get caller pid
-   sad lu+2			" match process table entry?
+   sad lu+2			" match mailbox status?
    skp				"  yes
    jmp 1b i			"   no, return
    -3
-   tad 8			" get pointer to pid in process table??
+   tad 8			" get pointer to process table entry
    dac 9f+t			" save in t0
 "** 01-s1.pdf page 17
-   lac o700000			" set high bits
-   tad 9f+t i
+   lac o700000
+   tad 9f+t i			" complement process status (mark ready)??
    dac 9f+t i
    jmp 1b i			" return from worker
 t = t+1
diff --git a/src/sys/s7.s b/src/sys/s7.s
index 27f1139..356e193 100644
--- a/src/sys/s7.s
+++ b/src/sys/s7.s
@@ -330,7 +330,7 @@ putcr: 0
    cla
    jmp putcr i
 
-intrp1:			" here with keyboard interrupt
+intrp1:			" here with TTY interrupt character
    lac d6		" get keyboard special device number
    dac .int1		" save as interrupt source
    lac d1
diff --git a/src/sys/s8.s b/src/sys/s8.s
index afce88c..6b88276 100644
--- a/src/sys/s8.s
+++ b/src/sys/s8.s
@@ -175,8 +175,11 @@ sysdata:			" system data 64 words saved to disk
 	"	4: out/notready??
 	"   bits 3:17 -- disk swap address/8
 	" second word: process pid
-	" third word:  used for smes/rmes
-	" fourth word: ??
+	" third word:  smes/rmes status:
+	"	0: not waiting
+	"	-1: this process waiting (rmes)
+	"	other: complement of sender pid
+	" fourth word: smes message
 ulist:
    0131000;1;0;0
    0031040;0;0;0

From 858fe3dd13d607e04425b7e855905f398e0ee0aa Mon Sep 17 00:00:00 2001
From: Phil Budne <phil@ultimate.com>
Date: Tue, 8 Mar 2016 12:10:31 -0500
Subject: [PATCH 3/4] notes on kernel & disk format

---
 src/sys/NOTES.md | 63 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 63 insertions(+)
 create mode 100644 src/sys/NOTES.md

diff --git a/src/sys/NOTES.md b/src/sys/NOTES.md
new file mode 100644
index 0000000..bc8ff11
--- /dev/null
+++ b/src/sys/NOTES.md
@@ -0,0 +1,63 @@
+PROCESSES
+=========
+
+uid -1 is superuser
+
+process 1 is "init", runs as superuser
+
+DISK
+====
+
+RB09: Burroughs fixed head disk (same hardware as RD10!)
+
+64 word sectors; 80 sectors/track; 100 tracks/surface; 2 surfaces
+8000 sectors/surface
+one surface reserved for backup
+
+512,000 words per surface: 1,024,000 characters!!!
+
+first disk block is copy of "system data"
+        contains time, free block information, process (user) list?!!
+
+12 word inodes (5 per block)
+710 sectors of inodes (max 3550 files)
+
+inode format
+------------
+   i.flags
+        400000  free?? (checked/toggled by icreat)
+        200000  large file
+        000040  special file
+        000020  directory
+        000017  can be changed by chmod.
+            10  owner read
+            04  owner write
+            02  world read
+            01  world write
+   i.dskps      7 block numbers (all indirect blocks if "large file")
+   i.uid        owner
+   i.nlks       link count
+   i.size       size (in words?)
+   i.uniq       unique value assigned at creation
+
+directory files can (only) be truncated by superuser
+
+directory node (dnode) format
+-----------------------------
+   d.i          i-number of file
+   d.name       four words, space padded
+   d.uniq       i.uniq value of file
+
+i numbers
+---------
+
+  1     core file?? (written by "sys save" or bad system call)
+  2     "dd"??? "root" directory
+  3     "system"??? default process cdir, must contain "init", "dd"
+
+  6     "ttyin" special file
+  7     "keyboard" (graphic-2) special file
+  8     "pptin"?? (paper tape reader) special file
+  10    "ttyout" special file
+  11    "display" (graphic-2) special file
+  12    "pptout" (paper tape punch) special file

From cf47a841b207e3044da3841be08a9a3aeb45abf3 Mon Sep 17 00:00:00 2001
From: Phil Budne <phil@ultimate.com>
Date: Tue, 8 Mar 2016 12:14:05 -0500
Subject: [PATCH 4/4] more markdown

---
 src/sys/NOTES.md | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/src/sys/NOTES.md b/src/sys/NOTES.md
index bc8ff11..6a33dd1 100644
--- a/src/sys/NOTES.md
+++ b/src/sys/NOTES.md
@@ -8,6 +8,7 @@ process 1 is "init", runs as superuser
 DISK
 ====
 
+```
 RB09: Burroughs fixed head disk (same hardware as RD10!)
 
 64 word sectors; 80 sectors/track; 100 tracks/surface; 2 surfaces
@@ -21,9 +22,11 @@ first disk block is copy of "system data"
 
 12 word inodes (5 per block)
 710 sectors of inodes (max 3550 files)
+```
 
 inode format
 ------------
+```
    i.flags
         400000  free?? (checked/toggled by icreat)
         200000  large file
@@ -39,18 +42,21 @@ inode format
    i.nlks       link count
    i.size       size (in words?)
    i.uniq       unique value assigned at creation
+```
 
 directory files can (only) be truncated by superuser
 
 directory node (dnode) format
 -----------------------------
+```
    d.i          i-number of file
    d.name       four words, space padded
    d.uniq       i.uniq value of file
+```
 
 i numbers
 ---------
-
+```
   1     core file?? (written by "sys save" or bad system call)
   2     "dd"??? "root" directory
   3     "system"??? default process cdir, must contain "init", "dd"
@@ -61,3 +67,4 @@ i numbers
   10    "ttyout" special file
   11    "display" (graphic-2) special file
   12    "pptout" (paper tape punch) special file
+```