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P.  16

READ  and  DATA

Up  to  now we've  looked  at  two ways  to  enter  numbers  into  a 

program.  One  is  by  assigning  a  value  to  a  letter  (A =  5).

Another  is  with  the  INPUT  statement.  Another method  is  with 

DATA.

Try  this :

10  DATA  1,2,3,4,5 

20  READ  A,B,C,D,E 

30  PRINT  A ;B ;C ; D ;E 

RUN  this  program.

NOTE:  DATA statements  can have  values  assigned with  commas 

separating  them;  same with  READ  statements.

DATA  lines  are  always  read  from  left  to  right by  READ  statements. 

It  does  not  matter where  DATA statements  come  in  the  sequence  of 

a  program.  Move  line  10  to  line  25.  Move  it  to  line  10000.  Works 

the  same  in  any  case.

TAB  Function

The  TAB  function  is  just  like  the  Tab  on  a  typewriter.  It  tells 

the  Computer  to  start  printing  at  a  specified number of  spaces 

in  from the  left.  Try  this:

10  PRINT  T A B (12),"

@

@

@

@

"

20  PRINT  T A B (32),"####”

RUN  it.

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Summary of Contents for TRS-80

Page 1: ...PRELIMINARY USER S MANUAL MICRO COMPUTER Catalog Numbers 26 1001 26 1201 14 841 Copyright 1977 by Radio Shack A Division of Tandy Corporation Fort Worth Texas 76107 U S A...

Page 2: ...ers tapes etc Save the packing material in case you need to transport the system Connecting the Video Monitor and Keyboard 1 Connect the power cord from the Video Monitor to a source of 120 volts 60 H...

Page 3: ...for 120 volt AC power 2 Connect the short cable DIN plug on one end and 3 plugs on the other to the TAPE jack on the back of the Keyboard Assembly Be sure you get the plug to mate correctly 3 The 3 pl...

Page 4: ...cond will blink indicating the program is loading When loading is done the TRS 80 will automatically t u n the CTR 41 off and flash READY on the screen You are then ready to RUN the program type in RU...

Page 5: ...m 5 When you are not going to use a CTR 41 for loading or recording programs do not leave RECORD or PLAY keys down press STOP 6 To REWIND or FAST Forward a cassette you must disconnect the plug from t...

Page 6: ...n it on again Pressing the power switch slowly can cause the machine to get confused Turn it on with a quick push Now type in P m and hit ENTER This is a test to see that the Computer powered up prope...

Page 7: ...press the backspace key repeat as necessary to erase the error If you have already ENTERed a line and notice an error type the same line over again the Computer always takes the last line typed in Let...

Page 8: ...ER The screen will display 17 5 1 9 318182 16 8 Press CLEAR and the screen will be blank except for the little cursor _ at the upper left hand comer If you want to recall the program that is in the Co...

Page 9: ...RINTinq Often you will want to put some wording in with your program to explain the meaning of calculations Try this PRINT THE APPROXIMATE VALUE OF PI IS 22 7 Hit ENTER The screen displays THE APPROXI...

Page 10: ...ore loading new programs from cassettes or typing in new programs Type 10 PRINT HELLO THERE I AM YOUR NEW TRS 80 MICROCOMPUTER RUN this one line program HELLO THERE I AM YOUR NEW TRS 80 MICROCOMPUTER...

Page 11: ...o handle very large and very small numbers For example the number 5 000 000 becomes 5E 06 this means the number 5 followed by 6 zeros The number 000 005 becomes 5E 06 this means 6 decimal places to th...

Page 12: ...to multiply X Y is for multiplication If you want to be sure your problems are calculated correctly use around operations which you want performed first NOTE INT RND and ABS functions are performed be...

Page 13: ...happens now Try other numbers Now change line 5 as follows 5 INPUT THE VALUE I WISH TO GIVE A IS A Delete line 10 type a line 10 and ENTER it with nothing else Run the program now and see what happen...

Page 14: ...ery powerful tool in the hands of an experienced programmer hang in there you ll become one Counting and Looping Try this 10 A 0 20 A A 1 30 PRINT A 40 GOTO 20 RUN it and see what happens To stop the...

Page 15: ...ly increases the number by 1 unless you tell it differently Change 10 to 10 FOR N 1 TO 10 STEP 2 RUN it Loops can be combined as long as the loops nest within each other ie finish one loop before goin...

Page 16: ...can have values assigned with commas separating them same with READ statements DATA lines are always read from left to right by READ statements It does not matter where DATA statements come in the seq...

Page 17: ...statements for almost any part of the screen Graphics Functions There are three Graphics statements SET RESET and POINT SET turns on a square on the screen RESET turns a square off POINT checks for t...

Page 18: ...0 TO 30 for Y Lines 70 and 90 set up 80 RESET X Y a loop for X Line 80 turns off 90 NEXT X 100 NEXT y the graphic display RUN the program The READY goofs of it up the display How to get rid How about...

Page 19: ...XT N RUN it Then add a comma at the end of line 20 and change the number for N so you can fill up the screen Then use a semi colon and change N again to fill up the screen before the program ends Abbr...

Page 20: ...ables for later READ statements READ X Y Z instructs Computer to READ values assigned by DATA statements RESTORE instructs Computer to start reading from first DATA statement PRINT X Computer will pri...

Page 21: ...t specified 1 is assumed NEXT N NEXT X used with FOR to complete a loop defining series for X STOP no abbr STOP used to stop a program END no abbr END optional to end a program GOTO G GOTO 1000 instru...

Page 22: ...le is evaluated and if X l Computer goes to 1000 if X 2 goes to 2000 etc ON X GOSUB 1000 2000 3000 multiple way branch to subroutine programs If X 4 Computer has no where to go and stops CLS clears th...

Page 23: ...at number END 100 returns or generates a random number between 1 and 100 END O returns or generates a random number between 0 and 1 END X returns or generates a random number with an upper limit equal...

Page 24: ...ust begin with a line number Information on a line may be up to 72 characters long In this case the screen display will overflow onto the next line but the Computer will interpret it as one line of in...

Page 25: ...Filing always INPUT the same number of variables as you PRINT If you print 3 input 3 otherwise errors may occur or data may be lost MISCELLANEOUS Remarks and documentation can be included in a program...

Page 26: ...es it is ready for entries it s your turn The prompt indicates the Computer is ready for a line number or other command If the Computer fails to turn the Cassette off at the end of a CLOAD or CSAVE yo...

Page 27: ...stir your imagination and creativity so you go on from here to make up your own Graphics and RND function 10 FOR X 0 TO 127 STEP N 20 N RND 5 30 FOR Y 0 TO 47 STEP 5 40 SET X Y 50 NEXT Y 60 FOR A 0 TO...

Page 28: ...HE OBJECT OF THE GAME IS FOR YOU TO GUESS 80 P THE NUMBER I AM THINKING OF IT IS FROM 0 90 P TO 100 ENTER 0 WHEN READY 105 IN P GOTO 110 110 LET X RND 100 115 CLS P P sP 117 LET F 0 LET Y 0 120 LET F...

Page 29: ...TO PLAY AGAIN 1 YES 0 NO IN G 380 IF G 1 THEN 110 390 CLS P P P P P RATS END Printing a Large X with TAB Function 5 CLS 10 X 0 20 Y 60 30 Y Y 4 40 X X 4 50 IF Y 0 THEN 140 60 IF X 28 THEN 100 70 IF X...

Page 30: ...RND 12 30 B RND 12 40 PRINT 50 PRINT A B WHAT 60 INPUT C 70 IF C A B GOTO 120 80 CLS 90 PRINT TRY AGAIN 100 PRINT 110 GOTO 40 120 CLS 130 p r i n t c o r r e c t 140 GOTO 10 To Use RUN and then enter...

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