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start Here Your first hours with a zx Computer can be bewildering as you try to make sense of the manual, and sort out just what you can do with your new possession. Mark Charlton, author of The Gateway Guide to the ZX80 and the ZX81. discusses some of the fundamental parts of the BASIC programming language. Although the program printouts are from a ZX81, all the material here applies to the zx Spectrum, and most of it to the ZX80. 40 ZX COMPUTING AUG/SEPT 1982 •
shown in the manual, then typing in SAVE followed by the name of the program within quote marks. In this case, I suggest you use the name ROCKET, so you would type in SAVE "ROCKET". Turn your cassette recorder on to record, after connecting it up as shown in the manual, and then press the NEWLINE/RETURN key. I suggest you make a habit of saving each program three times in a row, on a C-12 or C-15 (ie. computer) cassette, and that you only put one program on each side of a tape. Label the tape clearly with the load name (ie. with ROCKET in this case). Although it may seem wasteful to use up the whole side of a cassette with just one program recorded three times, the frustration you will save yourself by not having to search through tape after tape for a program you want will more than compensate for using more cassettes than is strictly necessary. The program is recorded three times just in case the tape gets damaged at some point, or you accidentally erase part of the program, or — as sometimes happens — one recording of the program refuses to load properly. You should clean the recorder's heads frequently us- Start Here ing liquid (not a tape cleaner ribbon in a cassette) to ensure the clearest possible signal is put onto the tape. Scientific notation Finally, in this article, we'll have a look at scientific notation. A computer uses what is known as scientific notation to display large numbers as a single digit and up to eight decimal places, followed by the letter E (for exponention) and the power of 10 to which the number is to be multiplied. Enter and run PROGRAM 12 (SCIENTIFIC NOTATION) which shows a variable (A) assigned to a number (1234) in line 20, then repeatedly printed out, then multiplied by 10. You can see (Fig. 2) part of the print out underneath the program listing. Note that after the number has nine trailing zeroes (1234000000000) it is printed as a number, a decimal point, more numbers after the decimal point, the letter E and a power of 10. Try and predict how long this program will run until it exceeds the maximum number possible on a ZX computer, then run it until it crashes to see if you were right. ZX COMPUTING AUGUST/SEPT 1982 45
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Page 3 and 4: Fully cased keyboard £37.95 Uncase
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Page 25 and 26: word Games The spectral Hangman rid
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Page 35 and 36: OHMRND" 90 PRINT RT 1 3 , 2 ; " N ,
Page 37 and 38: 18 PRINT "NUMBER OP WORDS TO E £ S
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Page 43 and 44: Graphics The PLOT thickens The IF..
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Page 49 and 50: !28240 • Lines 390 to 480 single
Page 51 and 52: 1 There's no special reason for our
Page 53 and 54: [ Sample printouts from J. K Graye
Page 55 and 56: I V i If you've ever struggled with
Page 57 and 58: 5 PRINT "SEEK" 10 DIM P(2) 20 DIM Z
Page 59 and 60: Machine Code Figure 1. 01 1A00 LD B
Page 61 and 62: Book reviews Caring for your comput
Page 63 and 64: is a characteristic of earlier Time
Page 65 and 66: Sorting it out This utility program
Page 67 and 68: Colourthello is intended to highlig
Page 69 and 70: 0 Level Physics Paul Holmes from Su
Page 71 and 72: DO you use A CASserre DCCH WITH YOU
Page 73 and 74: 60 PRINT BT 2,3; M i i W M T T T f
Page 75 and 76: ZX81 Spectrum 16K 1 MANAGEMENT GAME
Page 77 and 78: Some BASlCs do not allow a computed
Page 79 and 80: t an ling idile it /erto the EN >nt
Page 81 and 82: AS and B$. A$ holds information con
Page 83 and 84: 220 LET B1=P 225 LET Lfl=i 230 LET
Page 85 and 86: Vegas Breaker Chuck Hopper's progra
Page 87 and 88: y y Personal Software is a new quar
Page 89 and 90: ZX80 Carries 150 LET D = 0 350 IF B
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Graphics User-definable graphics Th
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frame counter as a timer use this r
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Specialist Book$ Choosing program*
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The Spectrum Listing 5 REM * MRTCHS
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Make sure you get every issue of ZX
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Business Keeping tabs on your chequ
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JRS SOFTWARE 19 WAYSIDE AVENUE. WOR
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11SO GOTO 1030 1150 LET X$ = X $ (
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The variables used are as follows;
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MELBOURNE HOUSE • ZX81 • SPECTR
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L£T B=B+1; BEEP .2,B*2S -4.0 LET G
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5 REM Pro g r am three 10 LET a$=CH
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2° Cassette E3: Fun to Learn serie
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ZX80 Dimensions Width 174mm (6.85 i
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Mathematical Operations And Functio
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FULLER FD SYSTEM £39*95 Profession
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