Section 2 - Commodore Computers

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May, 1982, Issue 24 116 . COMPUTEI COMPUTE! May. 1982. Issue 24 better way of detecting g errors. The most common CCRC that is used is a 16 bit polynomial, defined as (X + I 1 )*(X' )*(X* 15 + X + I). 1). By starting with a value e of zero in the CRC and passing g all the (lie received data through the CCRC routine. routine, when the final CRC received passes through the routine, the final result will be 0 (if {ifno errors were eencountered). There is no single besl best way to transfer programs via a modem, but bill there are some melhods methods which arc are better than olhers. others. *CPItH *C/V/W ;S is 1I a Iraril'Jllarlt trademark oj ofDigital Rt'search Research Computing A Checksum Checksum generates a sum of the data that is passed through it by adding (without any carry) each byte with the sum of the previous bytes. The checksum is initiallyy set to zero aand the final result is sent to be compared against the independently computed check sum atlhe the receiver computer. Since thee checksum is ann eighl eight bit value. value, only a single byte of data needs to be sent. It is quick and easy to perform this with a computer. The checksum method can onlyy reliably catch single bit errors. Although it does do reasonably well with wilh multibil Illultibit errors, the e percentages can rapidly drop lo to the realm of or coin toss odds. To use the checksum program enter it To use the checksum program enter it with the data in the accumulator. The result is saved in location CHKSUMC H for [i) r later use. The location CHKSUMC I-I M should be cleared to zero at the start of sending the data to zero at the start o f sending the data stream. stream, 8080 VERSION 6502 VERSION CHKSUM PUSH PSW CHKSUM PHA PUSH B PHP MOV LDA LOA ADD STA POP POP RET C,A CHKSUM C CHKSUM B PSW CLC ADC STA PLP PLA RTS CHKSUM CHKSUM This shortha nd version for th e 8080 This shorthand version for the 8080 assumes that at a register in the I CPU C does not get destroyed by the calling program, and that it is acceptable for the flags to be destroyed. not get destroyed by the calling program, and that it is acceptable for the flags to be d estroyed . 8080 VERSION 8080 VERSION CHKSUM ADDC C MOV C,A MOVC,A RET RET The CRC Method eRC computes CRC-1 6 crcsum from the poly CRC computes CRC-16 crcsum from the poly nomial nomiaI(X+l)*X"15 1)* X' + X X+l) + I) A CRC method of error detection is far supe superior to the checksum. By using a 16 Hi bit value e for the sum instead or ofan eight bit va value, e. a much improved detection capability is achieved. By using a polynomial of th the e proper type, the 16 bit va value can be used ra far r more effectively as well. The provided polynomial can detect errors or of up to 171 7 bits. Since the CRCSUM generated is a division remainder, r, a CRCSUMed CRCSUMcd data sequence can be verified ed by running the data through the CRC, and thenn running the e previously obtained CCRCSUM M throughh the CRC. Re. The resultant CRCSUMM should be zero. When the CRCSUM itself is transmittemined, , it should not be run through the e trans- CRC as this would disrupt the result. Also. Also, the MSB (1-1) {H } must be run through h the CRC first then followed by the LSB (L) { L } whenn checking the CRCSUM. To use li this routine, rOlltine, enter with the byte to be CRCSUMed in A (accumulator). TThe CRCSUMC is automatically tica y updated upon UPO Il passing the data through this is routine. 8080 VERSION 6502 VERSION CRC CRC2 2 A CRC method of error detection is rar bits. Si nce the CRCSUM generated is a C RC CRCI PUSH P PSW PUSH PUS H B8 PUSH H MVI B,8 8,8 LHLD LHLO CRCSUM RCL MOV C,A MOV A,L ADD AOO A MOV L.A MOV 1\-fOV A,H RAL MOV H.A RAL XRA C RRC JNC CRC2 MOV A,H XRI 80H MOV H,A H.A MOV A.L MOV XRI X IU MOV MOV DCR OCR JNZ SHLD POP POP POP RET ENO END A.L 051-1 H L.A A,C A,C B CRC I CRCSUM H CRCI CRCSUM H B PSW CRC PHP PHA STX XTEMP LDX LOX #0811 # 08>1 CRCI I ASL ADC AOC A #00H #OOH STA CRCTMP LDA LOA CRCSUM ASL A STA CRCSUM LDA LOA CRCSUM+1 J ROL A STA CRCSUM+1 CRCSUM+ J ROL A EOR CRCTMP LSR A BCC CRC2 LDA LOA CRCSUM+1 I EOR #80H STA CRCSUM+ + II LDA LOA CRCSUM EOR #5H #05H STA STA CRCSUM CRC2 LDA LOA CRCTMP CRCTM P DEX DEX BNE CRCI BNE LDX LOX PLA PLA PLP RTS ENO END CRCI XTEMP XTEMP
NEW PET/CBM SOFTWARE NEW PET/CBM SOFTWARE Let Computer Mat tum turn your Pet into a Home Arcade! ASTEROIDZ -— Its your ship vs. us. a swarm of killer gammaroidz. You are on a collision course and must destroy them before they blast you into the next galaxy. Four levels of play. Has hyperspace keys that move you around. Arcade style entertainment at its finest. Great graphics and sound. Casso Cass. 8K .............................. . . . ......... $9.95 MUNCHMAN -— How many dots can you cover? It's you against the computer munchers ZIP and ZAP. Can you dear clear the maze first or will they get you? Number keys move you up, down, right and left. GREAT GRAPHICS AND SOUND. Cass. 8K ....... .. ........ . . . . ... .. .......... . . $9.95 TARGET COMMAND -— Its you against a barrage of enemy lazeTs lazers that are aimed at your ammo dumps. Sight in on the targets and score as many hits as you dare. . As your skill increases 50 so does the the difficulty -— (5 levels to select). select), This is an arcade-style game with great graphics and sound effects. A must for your PET/CBM. ICBM. Casi;. Cass. 8K .. .. . .. .. .. .. .. .. .. .. .. . . .. . .. . .. . .... $9.95 ALL OUR SOFTWARE RUNS IN 8K BK OW· OLD-NEW ROM - 40 CHR. SCREEN WRITE FOR FREE CATALOG OF VIC/PET SOF1WARE SOFTWARE PLEASE ADD $1 SI.00 PER ORDER FOR SHIPPING COMPUTER MAT. • BOX 1664C. • LAKE HAVASU CITY, AZ. 86403 BD xes X PET/CBM' · PET/CBM 2000/3000/4000 4 0 Ser;es Series not; uSIng using a CRT, . or ddisplay controller r o chip $275.00· S275.OO* Select c t either r OOnn The BO SO x 25 SS or4Q 40 x 25 SB Built-m u ilt-In Display From the keyboBrd keyboard or program D'Splays ispla the full, origInal original character cter set Available from your locall dealer or: r : EXECOM CORP. 1901 19O1 PolariS Polaris Ave. RaCine Racme. . WI Wl 53404 0 4 Ph. 414-632-1004 414-639-1OO4 •*PlusP InstallatIon mstSllBtion charge change of $75.00 $75.OO Available AvaIlable only for BaSIC Basic 33.O .0 & S 8as Basic lc 4 -4.O .0 PET& PETS CBMb Tl,ts trademark e m a rk of <strong>Commodore</strong> Business USiness Machines ALTERNATE REALITY SOFTWARE SOFTWARE Presents for the Atari THEICHING THEICHING THE ANCIENT CHINESE BOOK OF DIVINATION • The complete text of the world's oldest book on disksk • 40K program ·73 •73 disk files fi!es(l55,OOO (155,OOObyles) bytes) ••Occupying 1211 I2ll disk sectors • High Resolution Graphics • Animation • Music and Sound Erfects Effects • Instructional instructional text material • Calculates and Displays Hexagrams • Displays Judgement, Image, Moving Lines for primary & secondary Hexagrams ••$44.95 order from: Ailernale Reality Software Alternate Reality Software 2111 W. Arapahoe Drive Littleton, LittielOn, Colorado 80120 Dealer inquiries invited Atari is a T T.M. of Atari, , Inc. NEW COMMODORE ADD-ONS RAM-ROM: GETS RID OF SAFING ROM GETS RID OF SAFING ROM MX-9100 CBM/PET RAM/ROM; •. Allows multi mulli ROM protected programs using the Ihe same socket to be put onto diskette· diskette, cassette, no need to insert protect ROM in socket after initial load, eliminates need for ROM switch box. box, write protect in software. software, decoded for dual ROM socket usage. usage, 4K expandable to 8K. easy internal CBM installation: $119.95 MX-232 CBM/PET TO RS-232C INTERFACE: Low cost, bidirectional. bidirectional, 50 to 19,200 baud rate. rate, full modem controls. controls, parity allows for two RS-232C CBM ports. ports, installs easily inside CBM: 5$199.95 SX-l00 SX-100IEEE-488/PET IEEE-488IPET MODEM SOFTWARE: Best 8100 modem software. software, by 8010 developer. developer, works with Source/MicroneVCBM Source/Micronet/CBM to disk/CBM to CBM; Intelligent Terminal Software: $79.95 MX-200IEEE-488/PET IEEE-488IPET PARITY MODEM/SOFTWARE Talk to a host computer requiring parity. parity, all feajures feaJures of SX232: $399.95 MX-113 THEFT PROTECTION ROM: Plug in ROM. displays owner's name. etc. when computer turned on: $49.95 ECX COMPUTER COMPANY ECX COMPUTER COMPANY 2678 NORTH MAIN ST. WALNUT CREEK. CA 94596 (415)944-92n (415)944-9277 For additional new product infonnation information and catalog send self addressed. addressed, stamped envelope.
Page 1 and 2: 1\ MALA Educational Programs M\~ Fo
Page 3 and 4: May. 1982. Issue 24 COMPUTEI 101 Ma
Page 5 and 6: • the battle for the moons of Jup
Page 7 and 8: May, May. 1Q82lssue 1982, Issue 24
Page 9 and 10: i i ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~,
Page 11 and 12: • Announcing the Printing Breakth
Page 13 and 14: May. 1982. Issue 24 COMPUTEI 111 Ma
Page 15 and 16: APPLE • ALTOS • ATARI • MAXEL
Page 17: CBM Maintenance In-House DOWNEY, CA
Page 21 and 22: CALL TOLL FREE CALL TOLL 800424 -27
Page 23 and 24: OLYMPIC SALES COMPANY 'ANY Vuthonze
Page 25 and 26: May, May. 1982, 1982. Issue 24 COMP
Page 27 and 28: OSI TRS-80 COLOR-80 OSI OSI TRS-80
Page 29 and 30: THEE MOSAIC 32K RAM FOR ATARI 32K R
Page 31 and 32: VOUNEED YOU NEED SpeedRead+ • Opt
Page 33 and 34: MOV, May, 1Q82, 1982, Issue 2A 24 C
Page 35 and 36: May. May, 1982, Issue 24 2.::1 COMP
Page 37 and 38: May, 1982, Issue 24 COMPUTEI 135 Ma
Page 39 and 40: MENAGERIE . ... $11.95 GRAFIX MENAG
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Page 43 and 44: May. JIAov, 1982. 1Q82,lssue Issue
Page 45 and 46: May, 1982. 1982, Issue l$Sue 7& 2.4
Page 47 and 48: Micrn BEST PRICES BEST PRICES VIC-2
Page 49 and 50: May, May.1982, Issue 24 COMPUTEI ,.
Page 51 and 52: May, 1982.I$Ue 24 COMPUTEI 149 May,
Page 53 and 54: May, 1982, 19S2. Issue 201 24 COMPU
Page 55 and 56: tvk:rv. 1Q82.lssue 24 COMPUTEI 153
Page 57 and 58: ASERT yourself", with CFI's new Dat
Page 59 and 60: The retailer contains The retailer
Page 61 and 62: BgeREM* * 900 1080 1000 DIM DIM Y '
Page 63 and 64: May, May. 1982. Issue 24 2A COMPUTE
Page 65 and 66: May. 1982. Issue 24 COMPUTE! PUTEI
Page 67 and 68: Program 1- Program I. 0000 13131313
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Mov. May. 1982.lssue 1982, Issue 24
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May, 1982. 1982, Issue 24 211 COMPU
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May. WIoy. 1982, 1982. Issue 24 21:
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ECLECTIC SYSTEMS CORPORATION P.O. B
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ECLECTIC SYSTEMS CORPORATION P.O. 8
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SOFTWARE STREET PRESENTS &JOOOo@~~~
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COI'l1lnodore commodore SHOW SPECTA
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Lyco Computer Marketing & Consultan
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EXTRA SPECIAL SPECIALS K-razJI K-ra
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Section 2 - Commodore Computers

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