C SKIMMING, A LOOK AT PICTURE BOOK
C
C	DEC-11-GPBAA-B-LA
C
C	COPYRIGHT (C) 1974
C	DIGITAL EQUIPMENT CORPORATION
C	MAYNARD, MASSACHUSETTS 01754

C	THE INFORMATION IN THIS SOURCE LISTING IS SUBJECT TO
C	CHANGE WITHOUT NOTICE AND SHOULD NOT BE CONSTRUED AS A
C	COMMITTMENT BY DIGITAL EQUIPMENT CORPORATION.
C	DIGITAL EQUIPTMENT CORPORATION ASSUMES NO RESPONSIBILITY
C	FOR ANY ERRORS THAT MAY APPEAR IN THIS LISTING.

C	THIS SOFTWARE IS FURNISHED TO THE PURCHASER
C	UNDER A LICENSE FOR USE ON A SINGLE COMPUTER 
C	SYSTEM AND CAN BE COPIED (WITH INCLUSION OF DIGITAL'S
C	COPYRIGHT NOTICE) ONLY FOR USE IN SUCH SYSTEM, EXCEPT AS
C	MAY OTHERWISE BE PROVIDED IN WRITING BY DIGITAL.

C	DIGITAL EQUIPMENT CORPORATION ASSUMES NO RESPONSIBILITY
C	FOR THE USE OR RELIABILITY OF ITS SOFTWARE ON EQUIPMENT 
C	THAT IS NOT SUPPLIED BY DIGITAL.
C
C WRITTEN BY BOB FRIEDENTHAL
C
C FEBRUARY 25, 1972
C
C A DEMO OF PICTURE BOOK GRAPHICS
C
	DIMENSION IARRAY(12)
	DATA IARRAY/'A','B','C','D','E','F','G','H','I','J','K','L'/

	CALL SCALE(0.,1023.,0.,1023.)
1000	CALL THEEND
	DO 100 I=1,13
	CALL CURSOR(0,1)
	CALL CURSOR(-1,1)
100	CONTINUE
	WRITE(5,1)
1	FORMAT('+','"SKIMMING"',//T21,'A LOOK AT PICTURE BOOK')
	DO 109 I=1,20
	CALL CURSOR(-1,0)
109	CONTINUE
	DO 108 I=1,10
	CALL CURSOR(1,0)
108	CONTINUE
	CALL IOTA(1)
	CALL HOLD(70)
	WRITE(5,2)
2	FORMAT(1X,'FIRST LET''S START THE CLOCK TICKING USING,'//,
	1 T20,'CALL IOTA(1)'//)
	CALL IOTA(1)
	CALL HOLD(50)
	WRITE(5,1002)
1002	FORMAT(T20,'CALL IOTA(0)',//
	1 1X,'RETURNS THE NUMBER OF TICKS THAT HAVE OCCURRED:'//)
	CALL HOLD(40)
	DO 101 I=1,10
	J=IOTA(0)
	WRITE(5,3),J
3	FORMAT(1X,T25,I5/)
101	CONTINUE
	CALL HOLD(40)
	WRITE(5,1003)
1003	FORMAT(//1X,'NEXT WE''LL SCALE THE SCREEN WITH,'//
	1 T20, 'CALL SCALE(0.,1023.,0.,1023.)'//)
	CALL HOLD(50)
	WRITE(5,4)
4	FORMAT(//1X,'AND LAYOUT OUR BOOK'/)
	CALL HOLD(40)
	CALL LAYOUT(15,72,20,30,2,20,1,100,5,10,0)
	WRITE(5,5)
5	FORMAT(1X,'USING,',//T20,'CALL LAYOUT(15,72,20,30'
	1 ,',2,20,1,100,5,10,0)'//)
	CALL HOLD (40)
	WRITE(5,6)
6	FORMAT(1X,'THIS CREATES A BOOK CONSISTING OF:'//
	1 T20,'15 LINES OF SCROLLING 72 CHARACTERS LONG',/
	1T20,'20 PICTURES, 30 LINES LONG',/
	1 T20,'2 FIGURES, 20 LINES LONG',/
	1 T20,'1 GRAPH, 100 LINES LONG',/
	1 T20,'5 TABLES, 10 LINES LONG, WITH ENGLISH CHARACTERS'//)
	CALL HOLD (150)
	WRITE(5,7)
7	FORMAT(1X,'AN 8K GT40 HAS ROOM FOR A BOOK 6000 INCHES LONG',/
	1 1X, 'EACH LINE OF SCROLLING REQUIRES 44 INCHES',/
	1 1X,'EACH PICTURE LINE TAKES 3 INCHES',/
	1 1X,'ALL OTHER LINES TAKE 1 INCH EACH',/
	1 1X,'THE MARGIN BETWEEN EACH PAGE TAKES 3 INCHES',/
	1 1X,'AND EACH INDEX ENTRY (1 FOR EACH PAGE), TAKES 2 INCHES'//)
	CALL HOLD (200)
	WRITE(5,8)
8	FORMAT(1X,'INITIALLY PAGE 0 OF EACH PAGE TYPE IS OPEN',/
	1 1X,'AND EACH PAGE''S MARKER POINTS TO LINE 0'//)
	CALL HOLD (80)
	WRITE(5,9)
9	FORMAT(1X,'IF WE DRAW AN ABSOLUTE POINT,'//
	1 T20,'CALL DOT(100.,100.)'//)
	CALL DOT (100.,100.)
	CALL HOLD (40)
	WRITE(5,10)
10	FORMAT(1X,'IT WILL ENTER PICTURE 0, LINE 0'//)
	CALL HOLD (80)
	WRITE(5,11)
11	FORMAT(1X,'THE MARKER FOR THAT PAGE WILL AUTOMATICALLY POINT',/
	1  ' TO LINE 1'/)
	CALL HOLD(60)
	WRITE(5,111)
111	FORMAT(/1X,'TO RESET THE MARKER TO THE START OF THE PAGE,'//
	1 T20,'CALL MARKP(0)'//)
	CALL MARKP(0)
	CALL HOLD(100)
	WRITE(5,12)
12	FORMAT(1X,'IF WE THEN,',//T20,'CALL BITS(1,3,3,0)',//
	1 1X,'WHICH SETS THE MODE OF THE PICTURE ENTRY TO:',//
	1 T20,'BLINK',/
	1 T20,'INTENSITY 3',/
	1 T20,'DOTDASH',/
	1 T20,'NON-LIGHT PEN SENSISTIVE,',///)
	CALL BITS(1,3,3,0)
	CALL HOLD (120)
	WRITE(5,13)
13	FORMAT(1X,'WE CAN REPLACE THE DOT'
	1 ' WITH A VECTOR OF THESE MODES USING,',//
	1 T20,'CALL VECTOR(200.,200.)'//)
	CALL VECTOR(200.,200.)
	CALL HOLD (100)
	WRITE(5,14)
14	FORMAT(1X,'TO CHANGE THE MODE OF FUTURE GRAPHICS TO'/,
	1 1X,'NON-BLINK, INTENSITY 5, SOLID, ',
	1 'LIGHT PEN SENSITIVE,'//
	1 T20,'CALL BITS(0,5,0,1)'//)
	CALL BITS (0,5,0,1)
	CALL HOLD (100)
	WRITE(5,15)
15	FORMAT(1X,'IF WE ISSUE A,'//
	1 T20,'CALL VECFIG(0,0)'//)
	CALL VECFIG(0,0)
	CALL HOLD(60)
	WRITE(5,16)
16	FORMAT(1X,'THIS SUB-PAGE CALL TO FIGURE 0 STARTING AT LINE 0',/
	1 1X,'WILL TAKE ON THESE MODES'//)
	CALL HOLD(50)
	WRITE(5,17)
17	FORMAT(1X,'THEREFORE, ANYTHING WE DRAW IN FIGURE 0',/
	1 1X,'WILL RESPOND TO LIGHT PEN HITS'//)
	CALL HOLD (50)
	WRITE(5,18)
18	FORMAT(T20,'CALL NOJOT(-40.,0.)',//
	1 1X,'DRAWS AN INVISIBLE JOT IN FIGURE 0'//)
	CALL NOJOT(-40.,0.)
	CALL HOLD(50)
	WRITE(5,19)
19	FORMAT(T20,'CALL ARC(80.,20,6.28,0.,.75)',//
	1 1X,'DRAWS AN ELLIPSE OF DIAMETER 80., WITH 20 SIDES,'
	1 1X,'A FULL 360 DEGREE ARC,',/
	1 1X,'TILTED 0 DEGREES FROM THE HORIZONTAL,'/
	1 1X,'WITH ITS Y DIAMETER 75 PERCENT OF ITS X DIAMETER'///)
	CALL HOLD(40)
	CALL ARC(80.,20,6.283,0.,.75)
	CALL HOLD(160)
	WRITE(5,20)
20	FORMAT(1X,'THE COORDINATES OF A LIGHT PEN HIT ON THIS ELLIPSE',/
	1 1X,'WILL AUTOMATICALLY ENTER THE VECTOR IN PICTURE 0, LINE 0',/
	1 1X,'MOVING IT AND, WITH IT, ALL THE NON-ABSOLUTE GRAPHICS',
	1 ' THAT FOLLOW IT',//
	1 1X,'TRY HITTING IT WITH THE LIGHT PEN'//)
	CALL HOLD(80)
	WRITE(5,21)
21	FORMAT(T20,'CALL LINEX(0,0)',//
	1 1X,'WILL RETURN THE X COORDINATE OF PICTURE 0, LINE 0',//
	1 1X,'AS THE ELLIPSE MOVES, WE CAN LIST '
	1 'THE X COORDINATE OF ITS CENTER:',//)
	CALL HOLD(90)
	DO 103 I=1,15
	J=LINEX(0,0)
	WRITE(5,3),J
103	CONTINUE
	CALL HOLD(80)
	WRITE(5,22)
22	FORMAT(///T20,'CALL SET(400.,350.)'//
	1 1X,'WILL DRAW AN INVISIBLE ABSOLUTE POINT',/
	1 1X,'WHICH NEVER MOVES'//)
	CALL SET(400.,350.)
	CALL HOLD(90)
	WRITE(5,23)
23	FORMAT(1X,'NOW WE CAN,'//
	1 T20,'CALL TEXT (10,IARRAY)'//
	1 1X,'WHICH WRITES 10 CHARACTERS FROM IARRAY INTO THE OPEN',
	1 ' TABLE'//)
	CALL TEXT(10,IARRAY)
	CALL HOLD(80)
	WRITE(5,24)
24	FORMAT(T20,'CALL TABLE (0,0)',//
	1 1X,'DISPLAYS THEM, ALWAYS AS ITALICS'//)
	CALL TABLE(0,0)
	CALL HOLD(50)
	WRITE(5,241)
241	FORMAT(1X,'USING THE CALL SET AND CALL TABLE,'/
	1 1X,'WE CAN DISPLAY THIS TABLE FROM MANY PLACES ON THE SCREEN,'/
	1 1X,'STARTING FROM ANY LINE IN THE TABLE'//)
	CALL HOLD(50)
	CALL SET(780.,600.)
	CALL TABLE(0,2)
	CALL HOLD(50)
	CALL SET(700.,300.)
	CALL TABLE(0,4)
	CALL HOLD(50)
	CALL SET (200.,300.)
	CALL TABLE(0,6)
	CALL HOLD(90)
	WRITE(5,25)
25	FORMAT(T20,'CALL MARKT(8)',//
	1 1X,'WILL POINT TABLE 0''S MARKER TO CHARACTER 8',/)
	CALL MARKT(8)
	CALL HOLD(50)
	WRITE(5,26)
26	FORMAT(1X,'AND,'//
	1 T20,'CALL TEXT(1,''+'')',//
	1 1X,'WILL CHANGE THAT CHARACTER TO "+"',/)
	CALL HOLD(90)
	CALL TEXT(1,'+')
	CALL HOLD(60)
	WRITE(5,261)
261	FORMAT(1X,'WE CAN EXTEND THE TABLE BY CONTINUING TO',
	1 ' WRITE IN IT'//)
	CALL HOLD(40)
	DO 2031 I=1,12
	CALL TEXT(1,IARRAY(I))
2031	CONTINUE
	CALL HOLD(60)
	WRITE(5,27)
27	FORMAT(1X,'TO DRAW A GRAPH, WE''LL FIRST SET THE INCREMENT'/,
	1 ' TO 20 USING,'//
	1 T20,'CALL PLOT(-20)',//)
	CALL PLOT (-20)
	CALL HOLD(30)
	WRITE(5,28)
28	FORMAT(1X,'THEN PLOT A FEW POINTS WITH,',//
	1 T20,'CALL PLOT(N)',//)
	DO 104 I=10,100,10
	CALL PLOT(I+0)
104	CONTINUE
	CALL HOLD(80)
	WRITE(5,29)
29	FORMAT(1X,'AND DISPLAY IT ALONG THE X AXIS WITH,',//
	1 T20,'CALL XGRAPH(0,0)',//)
	CALL XGRAPH(0,0)
	CALL HOLD(90)
	WRITE(5,30)
30	FORMAT(1X,'CHANGING THE INCREMENT,'/)
	DO 105 I=20,200,1
	CALL PLOT(-I)
105	CONTINUE
	WRITE(5,31)
31	FORMAT(1X,'AFFECTS ALL THE POINTS'//)
	CALL HOLD(30)
	WRITE(5,32)
32	FORMAT(1X,'SINCE WE NEVER CHANGED MODES,',/
	1 1X,'THE TABLE AND THE GRAPH WILL RESPOND TO THE LIGHT PEN'//
	1 1X,'TRY TOUCHING THE LIGHT PEN TO THE CHARACTERS'/)
	CALL HOLD(100)
	WRITE(5,33)
33	FORMAT(1X,'THE COORDINATES IN PICTURE 0, LINE 0 WILL CHANGE'//
	1 1X,'PICTURE BOOK WILL ALSO SAVE THE PICTURE NUMBER AND LINE',/
	1 1X,'OF THE LAST LIGHT PEN HIT'//)
	CALL HOLD(60)
	WRITE(5,34)
34	FORMAT(T20,'CALL HIT(N,M)',//
	1 1X,'RETURNS THESE VALUES:'//)
	CALL HIT(N,M)
	WRITE(5,3)N,M
	CALL HOLD(80)
	WRITE(5,35)
35	FORMAT(//1X,'NOW LET''S DISABLE THE LIGHT PEN FOR FUTURE'
	1 ,' GRAPHICS WITH,'//
	1 T20,'CALL BITS(0,4,0,1)',//)
	CALL BITS(0,4,0,1)
	CALL HOLD(30)
	WRITE(5,36)
36	FORMAT(1X,'AND ISSUE A CALL TO PICTURE 5, LINE 3 USING,'//
	1 T20,'CALL PICTURE (5,3)',//)
	CALL PICTUR(5,3)
	CALL HOLD(50)
	WRITE(5,37)
37	FORMAT(1X,'NOW IF WE OPEN THIS PAGE:',//
	1 T20,'CALL OPENP(5)',//)
	CALL OPENP(5)
	CALL HOLD(30)
	WRITE(5,38)
38	FORMAT(1X,'AND SET ITS MARKER TO 3 WITH,',//
	1 T20,'CALL MARKP(3)',//)
	CALL MARKP(3)
	CALL HOLD(30)
	WRITE(5,39)
39	FORMAT(1X,'A VECTOR WE DRAW USING,'//
	1 T20,'CALL VECTOR(100.,0.)',//)
	CALL VECTOR(100.,0.)
	CALL HOLD(30)
	WRITE(5,40)
40	FORMAT(1X,'WILL DISPLAY',///
	1 1X,'IF WE CONTINUALLY RESET THE MARKER TO LINE 3,'/
	1 1X,'AND REDRAW THE VECTOR,'//)
	DO 106 I=1,100
	CALL MARKP(3)
	CALL VECTOR (ALOG10(FLOAT(I))*175.,
	1 SIN(FLOAT(I)/5.)*100.)
106	CONTINUE
	WRITE(5,41)
41	FORMAT(1X,'WE CAN ALTER ITS LENGTH AND DIRECTION',//)
	CALL HOLD(50)
	WRITE(5,42)
42	FORMAT(1X,'WE CAN ERASE PICTURE 5 BY SETTING THE MARKER TO 3',
	1 ' AND ISSUING,'//
	1 T20,'CALL ERASEP'//)
	CALL HOLD(60)
	CALL MARKP(3)
	CALL ERASEP
	CALL HOLD(20)
	WRITE(5,43)
43	FORMAT(1X,'SIMILARLY WE CAN ERASE THE TABLE,'/)
	CALL HOLD(20)
	CALL MARKT(0)
	CALL ERASET
	WRITE(5,44)
44	FORMAT(1X,'THE GRAPH,'/)
	CALL HOLD(20)
	CALL MARKG(0)
	CALL ERASEG
	WRITE(5,45)
45	FORMAT(1X,'AND THE FIGURE',/)
	CALL HOLD(20)
	CALL MARKF(0)
	CALL ERASEF
	CALL HOLD(40)
	WRITE(5,46)
46	FORMAT(1X,'TO ERASE PICTURE 0, WE OPEN IT WITH,',//
	1 T20,'CALL OPENP(0)',//)
	CALL OPENP(0)
	CALL HOLD(40)
	WRITE(5,461)
461	FORMAT(1X,'MARK IT WITH,',//T20,'CALL MARKP(0)',//)
	CALL MARKP(0)
	CALL HOLD(20)
	WRITE(5,462)
462	FORMAT(1X,'THEN,'//
	1 T20,'CALL ERASEP',//)
	CALL OPENP(0)
	CALL HOLD(20)
	CALL ERASEP
	CALL HOLD(40)
	WRITE(5,47)
47	FORMAT(1X,'NOW LET''S STOP THE CLOCK:',//
	1 T20,'CALL IOTA(-1)'//)
	CALL HOLD(50)
	WRITE(5,48)
48	FORMAT(1X,'TO RESET THE BOOK TO ITS ORIGINAL CONFIGURATION,'//
	1 T20,'CALL THEEND',//)
	CALL HOLD(60)
	CALL THEEND
	CALL IOTA(1)
	CALL HOLD(40)
	WRITE(5,49)
49	FORMAT(1X,'THE BOOK NOW SCROLLS 30 LINES,'/
	1 1X,'HAS 1 FIGURE, 1 GRAPH, AND 1 TABLE EACH 1 LINE LONG',/
	1 1X,'AND ENOUGH 100 LINE PICTURES',/
	1 1X,'TO FILL THE REMAINING INCHES'//)
	CALL HOLD (150)
	WRITE(5,50)
50	FORMAT(1X,'THE PICTURE BOOK MANUAL DESCRIBES THE SUBROUTINES',
	1 ' WE HAVE USED',/
	1 1X,'AS WELL AS THE OTHERS AVAILABLE'//)
	CALL HOLD(80)
	WRITE(5,51)
51	FORMAT(1X,'NOW WE''LL START AGAIN FROM,'///)
	CALL HOLD(60)
	GOTO 1000
	STOP
	END
C HOLD, WAIT ROUTINE FOR SKIMMING
C
C DEC-11-GPBA-A-LA
C
C COPYRIGHT 1973
C DIGITAL EQUIPMENT CORPORATION
C MAYNARD, MASS. 01754
C
C WRITTEN BY BOB FRIEDENTHAL
C
C FEBRUARY 25, 1973
C
C HOLD WAITS THE NUMBER OF SECONDS SPECIFIED IN THE ARGUMENT
C AS COUNTED BY THE PDP-11/05'S CLOCK
C
	SUBROUTINE HOLD(N)
	J=IOTA(0)
1	K=IOTA(0)
	DO 2 I=0,N*1000
2	CONTINUE
	IF(K-J.LT.0)K=K+4095
C			TEST FOR CLOCK WRAPAROUND
	IF(K-J.LT.N*6)GOTO 1
	RETURN
	END