TRIPOS PDP-11 Assembler version 1.4 ; GT40 demo program. ; Display a blob of light which follows the light pen around the screen. ; (ie it can be dragged). ; Martin Guy, June 1988. ; Constants about machine. 040000 COREND = 40000 ; First unusable word 002000 WIDTH = 1024. ; Height of display 001400 HEIGHT = 768. ; Width of display ; Address of registers. 172000 DPC = 172000 ; VT40 Program counter 172002 DSR = 172002 ; VT40 Status register 172004 XSR = 172004 ; X status register 172006 YSR = 172006 ; Y status register ; Recommended mnemomics 100000 CHAR = 100000 ; Character mode 104000 SHORTV = 104000 ; Short vector mode 110000 LONGV = 110000 ; Long vector mode 114000 POINT = 114000 ; Point mode 120000 GRAPHX = 120000 ; Graphplot X mode 124000 GRAPHY = 124000 ; Graphplot Y mode 130000 RELATV = 130000 ; Relative point mode 002000 INT0 = 2000 ; Intensity modes 002200 INT1 = 2200 002400 INT2 = 2400 002600 INT3 = 2600 003000 INT4 = 3000 003200 INT5 = 3200 003400 INT6 = 3400 003600 INT7 = 3600 000100 LPOFF = 100 ; Light pen off 000140 LPON = 140 ; and on 000020 BLKOFF = 20 ; Blink off 000030 BLKON = 30 ; and on 000004 LINE0 = 4 ; Solid line 000005 LINE1 = 5 ; Long dash 000006 LINE2 = 6 ; Short dash 000007 LINE3 = 7 ; Dot dash 160000 DJMP = 160000 ; Display jump 164000 DNOP = 164000 ; Display NOP 170000 STATSA = 170000 ; Load status A 173400 DSTOP = 173400 ; Display stop and interrupt 001400 SINON = 1400 ; Stop interrupt on 001000 SINOFF = 1000 ; Stop interrupt off 000200 LPLITE = 200 ; Light pen hit on 000300 LPDARK = 300 ; and off 000040 ITAL0 = 40 ; Italics off 000060 ITAL1 = 60 ; and on 000004 SYNC = 4 ; Halt and resume in Sync 174000 STATSB = 174000 ; Load status B 000100 INCR = 100 ; Graphplot increment 040000 INTX = 40000 ; Intensify vector or point 001777 MAXX = 1777 ; Max delta-x 001377 MAXY = 1377 ; Max delta-y 020000 MINUSX = 20000 ; -ve delta-x 020000 MINUSY = 20000 ; -ve delta-y 017600 MAXSX = 17600 ; Max delta-x in short mode 000077 MAXSY = 77 ; Max delta-y 020000 MISVX = 20000 ; -ve delta-x 000100 MISVY = 100 ; -ve delta-y 000000' .PSECT ; Simple PDP-11 program 000000' 012706 037776 MOV #COREND-2,SP ; Set up stack ; Constants held in registers for quick access 000004' 012705 172000 MOV #DPC,R5 ; Address of DPU program counter 000010' 012704 000116' MOV #STARTY,R4 ; Address of starting y coordinate in DPROG 000014' 012703 000112' MOV #DLOOP,R3 ; continuation address for DPU after DSTOP ; Set up interrupt vectors 000020' 012737 000060' 000320 MOV #STOPINTR,@#320 ; DPU DSTOP instruction (priority level 4) 000026' 012737 000200 000322 MOV #200,@#322 ; new CPU priority = 4 - no nested intrs 000034' 012737 000100' 000324 MOV #LPINTR,@#324 ; Light Pen hit 000042' 012737 000200 000326 MOV #200,@#326 ; new CPU priority = 4 - no nested intrs 000050' 012715 000106' MOV #DPROG,(R5) ; Start graphics processor 000054' 000001 LOOP: WAIT ; Mouch about... 000056' 000776 BR LOOP ; Display program: full-screen raster scan ; What to do on a Display Stop interrupt 000060' STOPINTR: 000060' 005314 DEC (R4) ; move down one raster line 000062' 005314 DEC (R4) ; move down one raster line 000064' 100402 BMI L1 ; if off bottom of screen, start again at top 000066' 010315 L2: MOV R3,(R5) ; Restart graphics processor 000070' 000002 RTI 000072' 012714 001377 L1: MOV #HEIGHT-1,(R4) 000076' 000773 BR L2 ; Light pen interrupt service routine 000100' LPINTR: 000100' 012715 000001 MOV #1,(R5) ; Continue display 000104' 000002 RTI ; Display program 000106' DPROG: ; Set up, point mode, intensity 4, no light pen or ; blink and solid lines. Move to (500, 500). Enter ; long vector mode 000106' 116524 POINT+INT2+LPOFF+BLKOFF+LINE0 000110' 171240 STATSA+SINOFF+LPLITE+ITAL0 000112' DLOOP: 000112' 114000 POINT 000114' 000000 STARTX: 0 000116' 001377 STARTY: HEIGHT-1 000120' 110000 LONGV 000122' 041777 DX: INTX+WIDTH-1 ; left to right 000124' 000000 DY: 0 000126' 000000 0 ; down a line 000130' 020001 MINUSY+1 000132' 061777 INTX+MINUSX+WIDTH-1 ; and back 000134' 000000 0 000136' 173400 DSTOP 000140' END: .END No errors detected Assembly statistics (words): Absolute Relocatable Code 0 48 Reloc. info 0 5 Space used for symbol table: 1060 words Total workspace used: 1260 words Assembly complete