Committing changes for LCM+L's PDP-7 hardware: removing interrupt code

for nonexistent devices (GRAPHIC II, Dataphone, etc.) and rewriting RB09 disk code to use our programmed-IO disk device, dubbed the JK09. This includes bootstrap code for same.
2026-04-17 08:51:02 +00:00 · 2019-10-30 11:46:37 -07:00
parent 9c8e5f5f2c
commit f6b16bedb0
5 changed files with 170 additions and 165 deletions
--- a/build/Makefile
+++ b/build/Makefile
@@ -24,7 +24,7 @@ BINDIR=bin
 TESTDIR=tests
 BINARIES=../binaries/

-all: cmd others a.out boot.rim image.fs
+all: cmd others a.out boot.rim jkboot.rim image.fs

 # Make alternative everything: no dd but . and ..
 alt: altcmd altothers boot.rim alt/a.out alt/image.fs
@@ -70,6 +70,11 @@ alt/a.out: $(ALTSYS)
 boot.rim: $(SYSSRC)/sop.s $(OTHERSRC)/pbboot.s
 	$(AS) -f rim -o boot.rim $(SYSSRC)/sop.s $(OTHERSRC)/pbboot.s

+# Josh's bootstrap code
+jkboot.rim: $(SYSSRC)/sop.s $(OTHERSRC)/jkboot.s
+	$(AS) -f rim -o jkboot.rim $(SYSSRC)/sop.s $(OTHERSRC)/jkboot.s
+	$(AS) -n -f list -o jkboot.lst $(SYSSRC)/sop.s $(OTHERSRC)/jkboot.s
+
 # Cold boot Unix kernel: attempts to build a minimal filesystem.
 # Don't use this one!
 COLDBOOT=$(SYS) $(SYSSRC)/s9.s
--- a/src/sys/s4.s
+++ b/src/sys/s4.s
@@ -56,7 +56,8 @@ free: 0
   jmp free i		" Return from the routine
 t = t+1

-	" "load ac indirect"
+	" load AC indirect (without using indirect!)
+	" need to avoid use of indirect in interrupt service routines
 	" AC/ address
 	"   jms laci
 	" AC/ contents of address
@@ -142,7 +143,7 @@ copyz: 0
 t = t+1

 	" Character queue management routines
-	" (CALLED FROM PI: USE OF INDIRECT AVOIDED TO AVOID DISK DMA UNDERRUN)
+	" (CALLED FROM PI: USE OF INDIRECT AVOIDED!)

 	" Queue numbers:
 	"  0: free list
@@ -311,7 +312,7 @@ dskrd: 0
   jms srcdbs			" in memory?
      jmp 1f			"  yes
   lac dskaddr			" no: read from disk
-   jms dskio; 06000
+   jms dskio; 06000		
   jmp 2f
 1:
   dzm 9f+t+1 i
@@ -341,68 +342,61 @@ t = t+3
 	"   jms dskio; DSLD_BITS
 dskio: 0
   dac dskaddr
-   cll; idiv; 80
-   dac 9f+t
-   lacq
-   idiv; 10
-   dac 9f+t+1
-   lls 22
-   xor 9f+t+1
-   als 8
-   dac 9f+t+1
-   lac 9f+t
-   idiv; 10
-   dac 9f+t
-   lls 22
-   xor 9f+t
-   xor 9f+t+1
-   xor o200000
+   tad d8000	" start at logical block 8000
   dac 9f+t
   jms dsktrans; -64; dskbuf; 9f+t; dskio
   isz dskio
   jmp dskio i
-t = t+1
+t = t+2

 	" perform disk I/O (both filesystem buffer and swapping)
 	" passed physical (BCD) disk address
-	" waits for disk interrupt: no overlapped operation
-	" to avoid disk DMA underrun
 	" called:
-	"   jms dsktrans; -words; mem_addr; disk_addr_ptr; op_ptr_ptr
+	"   jms dsktrans; -WC; MAC; addr_ptr; dsld_ptr
 dsktrans: 0
-   -10				" set retry counter
-   dac 9f+t
-1:
   -1
-   tad dsktrans			" get arg pointer
+   tad dsktrans
   dac 12			" store as auto-index
 "** 01-s1.pdf page 26
-   dscs				" clear status register
-   lac 12 i			" pick up word count
-   dslw				" load WC
-   lac 12 i			" pick up memory address
-   dslm				" load MAC
-   lac 12 i			" get disk_addr_ptr
-   jms laci			" get disk address
-   dsld				" load BCD track and sector (TA & SA)
-   dzm .dskb			" clear disk interrupt indicator
-   lac 12 i			" load status (op) pointer pointer
+   lac 12 i
+   dac 9f+t			" stow word count
+   lac 12 i
+   dac 9f+t+1			" stow memory address
+   lac 12 i
   jms laci			" fetch pointer
+   jkld				" load JK disk address
+
+   lac 12 i
+   jms laci			" fetch operation (read/write) ptr
   jms laci			" fetch op
-   dsls				" load status register (sets busy, int enb)
-   lac .dskb			" check for interrupt
-   sna
-   jmp .-2			" loop until interrupt seen
-   lac .dske			" get status from interrupt
-   sma
+
+   sad o7000
+   jmp 2f			" this is a write
+   
+   " do a read operation
+1:
+   jkrd				" read next word
+   dac i 9f+t+1			" store it
+   isz 9f+t+1			" move to next address
+   isz 9f+t			" increment counter
+   jmp 1b			" do it again
+   jmp 3f			" done
+ 
+   " do a write operation 
+2: 
+   lac i 9f+t+1			" read word from memory
+   jkwr				" write to disk
+   isz 9f+t+1
+   isz 9f+t			" as above
+   jmp 2b			" do it again
+
+3:			 
   jmp 12 i			" return
-   isz 9f+t			" increment retry counter
-   jmp 1b			"  less than 10 tries: try again
-   jms halt " 10 disk errors
-t = t+1
+
+t = t+2

 halt: 0
-   isz 9f+t			" spin for a while (process interrupts?)
+   isz 9f+t			" spin for a while (process interrupts)
   jmp .-1
   iof				" disable interrupts
   hlt				" halt
--- a/src/sys/s7.s
+++ b/src/sys/s7.s
@@ -4,62 +4,61 @@
 pibreak:		" priority interrupt break processing "chain"
   dac .ac		" save interrupt AC
 	"** CROSSED OUT....
-   dpsf			" skip on data phone flag set
-   jmp 1f		"  not set: check next device
+"   dpsf			" skip on data phone flag set
+"   jmp 1f		"  not set: check next device

-   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		" dpread = -1
-   lac dpstat		" get status back
-   ral			" rotate up
-2:
-   sma			" XMIT FLG set?
-   jmp piret		"  no: return from interrupt
-   -1
-   dac dpwrite		" dpwrite = -1
-   jmp piret	"** END OF CROSSOUT
+"   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		" dpread = -1
+"   lac dpstat		" get status back
+"   ral			" rotate up
+" 2:
+"   sma			" XMIT FLG set?
+"   jmp piret		"  no: return from interrupt
+"   -1
+"   dac dpwrite		" dpwrite = -1
+"   jmp piret	"** END OF CROSSOUT

-1: clsf			" clock overflow (60hz tick increment of loc 7 (-1))
+1: clsf			" clock overflow (line frequency ticks)?
   jmp 1f		"  no

-   lpb			" load display push buttons
-   dac pbsflgs		" save
+"   lpb			" load display push buttons
+"   dac pbsflgs		" save
   isz s.tim+1		" increment low order tick count
-   skp			"  no overflow, skip high order word increment
+   skp			"  no overflow, skip second increment
   isz s.tim		"   low order overflowed, increment high order count
-			"   ("never" skips: 36 bits overflows every 36 years!)
-   isz uquant		"    increment user quantum counter (ignore overflow)
-			"     (18 bits overflows in 72 minutes)
-	"** written: ttydelay -> ttyd1 ;
+   isz uquant		"    increment user quantum counter
+	"** written: ttydelay -> ttyd1
 	"** written: ttyrestart -> ttyres1
-cnop:			" constant location for iread (stored at iwrite!)
-   nop
+
+cnop:			" fetched as constant in iread
+   nop			
   -1
-   dac 7		" reset rt clock count to -1 (overflow on next tick)
-   clon			" enable clock interrupts, clear overflow flag
+   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
   isz ttydelay		"   no: done delaying?
   skp			"    not done
   jms ttyrestart	"     yes: start output
 	"** START CROSSED OUT: written: lac tty
-   lac .dspb
-   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
+"   lac .dspb
+"   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?
@@ -76,37 +75,37 @@ cnop:			" constant location for iread (stored at iwrite!)
   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
-   lac .dspb
-   sna
-   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 piret
-dsprestart:
-   lac d1
-   dac .dspb		" set .dspb = 1
-   lac dspbufp		" load display buf pointer
-   beg			" start display processor
-   -10
-   dac .dsptm		" set .dsptm = -10 (10 ticks)
-   jmp piret
+" 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
+"   tad dm3
+"   sna
+"   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
+"   -10
+"   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
-   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
+"   jmp piret

 1: ksf			" (TTY) keyboard flag set?
   jmp 1f		"  no
@@ -129,8 +128,8 @@ dsprestart:
   skp			"  yes
   jmp piret		"   no: done
   lac sfiles+1		" get ttyout sleep word
-   sma			" busy?
-   xor o400000		"  no, mark as busy now!
+   sma			" highest bit set?
+   xor o400000		" no, make it so (why???)
   dac sfiles+1		" save back

 "** 01-s1.pdf page 43
@@ -169,7 +168,7 @@ ttyrestart: 0
   tad o20		" bump by 16
   rcr			" divide by two
   cma			" complement
-   dac ttydelay		" save as delay countdown
+   dac ttydelay		" save
   jmp ttyrestart i
 2:
   lac sfiles+1		" run out of characters to send: wake user(s)
@@ -178,21 +177,21 @@ ttyrestart: 0
   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
-   dac char
-   sad o33		" code 33 (ESCAPE?)
-   jmp intrp2		"  yes: mark interrupt
-   lac d3
-   jms putchar
-      nop
-   lac sfiles+2
-   jms wakeup
-   dac sfiles+2
-   jmp piret
+"   cck			" yes: clear flag
+"   lck			" read character
+"   dac char
+"   sad o33		" code 33 (ESCAPE?)
+"   jmp intrp2		"  yes: mark interrupt
+"   lac d3
+"   jms putchar
+"      nop
+"   lac sfiles+2
+"   jms wakeup
+"   dac sfiles+2
+"   jmp piret

 1: rsf			" paper tape reader ready?
   jmp 1f		"  no
@@ -204,7 +203,7 @@ ttyrestart: 0
   sna			" have saved char?
   jmp .+5		"  no: jump to second rrb
   dac char		" yes: save as current char
-   rrb			" clear flag, read ptr buffer
+   rrb			" clear flag, read reader buffer
   dac npptchar		" save as saved char
   jmp .+3
   rrb			" here without saved char: read new
@@ -222,14 +221,14 @@ ttyrestart: 0
 2:
   lac npptchar		" get saved char (if any)
   sna			" had saved char?
-   jmp .+4		"  no
+   jmp .+4		"  no: wake up writer
   dac char		" yes: save as char to send
   dzm npptchar		" clear saved char
   jmp 3b
   rsa			" reader select alphanumeric mode
   lac sfiles+3
   jms wakeup		" wake sleepers; returns zero
-   xor o400000		" mark busy (rsa before sleep @ rppti)
+   xor o400000		" set high bit (rsa before sleep)
   dac sfiles+3
   jmp piret
 3:
@@ -256,37 +255,38 @@ ttyrestart: 0
   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
-   dac pbsflgs+1
+"   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
-   jms wakeup
-   dac sfiles+6
-   cla			" clear button lights
-   wbl
-   jmp piret	"** END CROSSED OUT
+"   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
+"   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
-   -1
-   dac crread
-   jmp piret
+"   crrb
+"   dac crchar
+"   -1
+"   dac crread
+"   jmp piret

-1: crrb			" clear CR flag for good measure???
+" 1: crrb			" read card reader buffer??

+1:
 piret:			" return from priority interrupt
   lac 0		" get LINK (in bit 0)
   ral			" restore LINK
@@ -314,7 +314,7 @@ wakeup: 0
   dac 9f+t
   sma			" high bit set?
   jmp 2f+2		"  no: skip the fun
-   lac o700000		" yes: decrement process status (mark ready)
+   lac o700000		" yes: decrement process status (wake)
 2: tad ..		" (avoiding indirect)
   dac ..
   lac 2b		" advance tad operand by 4 words
--- a/src/sys/s8.s
+++ b/src/sys/s8.s
@@ -68,7 +68,9 @@ o375: 0375
 o777: 0777
 o2000: 02000
 o4000: 04000
+o7000: 07000
 d7999: 7999
+d8000: 8000
 o10000: 010000
 o17762: 017762
 o17777: 017777
--- a/src/sys/sop.s
+++ b/src/sys/sop.s
@@ -56,6 +56,10 @@ dsls = 0707144			" DSK: load status
 dssf = 0707121			" DSK: skip on flags
 dsrs = 0707132			" DSK: read status register

+jkld = 0704624			" JK:  load block address
+jkrd = 0704612			" JK:  read word
+jkwr = 0704604			" JK:  write word
+
 iof = 0700002			" PIC: interrupts off
 ion = 0700042			" PIC: interrupts on
 caf = 0703302			" CPU: clear all flags