e Winter Consumer Electronics Show COMPUTErs $2.95 April 1986 ^ Issue 34, Vol. 4, No. 4 02220 $3.75 Canada TUflso copy Making copies of unprotected disks was never this easy — or this fast. Copy and fomnat an entire disk in only four-and-half minutes. For the Commodore 64. A Buyer's Guide To Printers An up-to-date printer comparison chart that helps you make the right purchase. >:\\\\\\\\\\\\v\\\\\\\OT Windows On The 1 28 Give your programs that polished look with the versatile WINDOW command. A hands-on tutorial with useful examples and tips. Machine Languag For Beginners: %j Cracking The KeriD II About CP/Mi ..he 128 ^^^^ 04 "7U86"02220i Directory Filer jstomize any disk directory with this quick and powerful utility. For the Commodore 64, Plus/4, and 16. Dunk Few completely master this fascinating 3-D game for the Commodore 64. Just when you think you see the pattern, it's gone. TEMPLE OF APSHAinaiiOGY h. 'WsiKms'im^ ■i:^ i X \ S^s?f.5 Wl You know 'Itmple of Apshal, Tht; chissic. Best-suller fur over four f/ears. You may have friends trapped forever in its dark recesses. Players have dropped from siglit for weeks at a time, searcliing for the treas u re s o f A psh ai . Well now we've raised the stakes. Introtkicinj! the mw Apsliai TVilogjJ. The combined wratli of the world famous Temple of Apshai®, Upper Reaches of Apshai® and Curse of Ra* .'Ml on a single disk. 1\velve levels. LifiS rooms to explore. More choices. More chances. Best of all, there's faster game play, The graphics and sounds are new. The challenge of the dungeons is timeless. Are you ready for the most involving role-playing game ever designed? Temple of Apshai is waiting. Silently lurking. Patiently waiting. For you. At your nearest Epy.v: dealer APPLE II MIC A»tl IBMK CM/1IB 'tl'mpk'of Apshai IHlofftf km:) Kiel Court, Siinnyviik', CA !M0H9 Stimegy Games for tim Action-Game Player liiii BATTERI j^ INCLUDED BATTERIES 'm^ INCLUDED Klchmond Hill, Ontario L4B IBS CANADA f4)6J88f-994I mlex: 06-21-8290 dSoftware lll'llll-.I.II^IL.I .1. .I...IUMI1W"111II1 75 Sky Park North, Sulmhm Irvine, California USA 927U 1416) 881-3816 7&/ex.'S09-lJ9 WHITE to US fOfl FULl COIOUB MTAIDSUE of ou( ptoducts lor C0MM0D0F1E, ATARI, APPLE and IBM SYSTEMS. FOn TECHNOL SUPf'OBT ORPRODUCT INFORMATION PLEASE PHONE 14161 881-9818. SOME PRGGfiAMSftRE NOT AVAILAOLffOR ALL SYSTEMS, Coinmodorg. Appla. Atari and IBM PC sre reaistwed itadomaflis ol Apple Coraputefs, Inc., Alari, Int , Comraodate Business Maehinos, Inc., and IntetriBlional BirttftBss Machines. rwpBclivelif Some Historic Breakthroughs DoNT Take As Much Explaining As CompuServe. But then, some historic breakthroughs could only take you from the cave to the tar pits and back again. CompuServe, on the other hand, makes a considerably more civilized contribution to your life. it turns that marvel of the 20th century, the personal computer, into something useful. Unlike most personal computer products you read atx3ut, CompuServe is an information service. It isn't software. It isn't hardware. And you don't even have to know a thing about programming to use it. You subscribe to CompuServe — and 24 hours a day, 7 days a week, it puts a universe of information, entertainment and communications right at your fingertips. A few of the hundreds of things you can do with CompuServe. COMMUNICATE EasyPlex™ Electronic Mail lets even beginners compose, edit, send and file messages the first time they get online. It puts friends, relatives and business associates — anywhere in the country — in constant, conven- ient touch. CB Simulator features 72 channels for "talking" with thousands of other enthusiastic subscribers throughout the country and Canada. The chatter is frequently hilarious, the "handles" unforgettable, and the friendships hard and fast. More than 100 Forums welcome your participation in "discussions" on all sorts of topics. There are Forums for computer owners, gourmet cooks, investors, pilots, golf- ers, musicians, you name it! Also, Electronic Conferencing lets busi- nesses put heads together without anyone having to leave the shop. Bulletin Boards let you "post" messages where thousands will see them. You can use our National Bulletin Board or the specialized Bulletin Boards found in just about every Forum. HAVE FUN Our full range of games includes "You Guessed it!", the first online TV-style game show you play for real prizes; and Mega Wars III, offering the ultimate in interactive excitement. I And there are board, parlor, sports and educational games to play alone or against other subscribers throughout the country. Movie Reviews keep that big night at the movies from being a five* star mistake. SHOP THE ELECTRONIC MALE" gives you convenient, 24-hour-a-day 7-day-a-week shopping for name brand ^x)ds and services at discount prices from nationally known stores and businesses, SAVE ON TRIPS Travelshopper™ lets you scan flight availabilities (on virtually any airline — world- wide), find airfare bargains and order tickets right on yourcomputer. , Worldwide Excliange sets you up [ with the perfect yacht, condo, villa, [ or whatever it takes to make your next ' vacation o Locator;. A to Z Travel/News Service provides the latest travel news plus complete information on over 20,000 hotels worldwide. MAKE PHI BETA KAPPA ' Grolier's Academic American Encyclopedia's Electronic Edition delivers a complete set of encyctope- dias right to your living room just in time for today's fiomework. It's continuously updated . . . and doesn't take an incti of extra shelf space. The College Board, operated tjy tliu College Entrance Examination Board, gives tips on preparing for the SAT, choosing a college and getting financial aid. KEEP HEALTHY Healthnet will never replace a real, live doctor— but it is an excellent and readily available source of health and medical information for the public. Human Sexuality gives the civiliza- tion that put a man on the moon an intelligent alternative to the daily "Advice to the Lovelorn" columns. Hundreds turn to it for real answers. BE INFORMED All the latest net^ is at your fingertips. Sources include the AP news wire (covering all 50 states plus national news), the Washington Post, USA TODAY Uixlate, specialized business and trade publica- tions and more. You [ can find out instantly what Congress I did yesterday; who finally won the game; and what's happening back in Oskaloosa with the touch of a button. And our electronic clipping service lets you tell us what to watch for. We'll electronically find, clip and file news for you. . . to read whenever yoLi'd like. INVEST WISELY Comprehensive investment help just might tell you more about the stock you're looking at than the company's Chairman of the Board knows. (Don't know who he is? Chances are, we can fill you In on that, too.) CompuServe gives you com- plete statistics on over 10,000 NYSE, AM EX and OTC securities. Historic trading statistics on over 50,000 stocks, bonds, funds, issues and options. Five years of daily com- modity quotes. Standard & Poor's. Value Line, And more than a dozen other investment tools. ~ Site II facilitates business decisions by providing you with demographic and sales potential information by state, county and zip code for the entire country National and Canadian business wires provide continuously updated news and press releases on hundreds of companies worldwide. GET SPECIALIZED INFORMATION Pilots get personalized flight plans, weather briefings, weather and radar maps, newsletters, etc. Entrepreneurs use CompuServe too for complete step-by-step guide- lines on how to incorporate the IBMs of tomorrow. Law>'ers, doctors, engineers, mil- itary veterans and businessmen of all types use similar specialized CompuServe resources pertinent to their unique needs. And now for the pleasant surprise. Although CompuServe makes the most of any computer, it's a remark- able value. With CompuServe, you get low start-up costs, low usage charges and local phone-call access in most major metropolitan areas. Here's exactly how to use CompuServe. First, relax. There are no advanced computer skills required. In fact, if you know how to buy breakfast, you already have the know-how you'll need to access any subject in our system. That's because it's "menu-driven," so beginners can simply read the menus (lists of options) that appear on their screens and then type in their selections. Experts can skip the menus and just type in "GO" followed by the abbreviation for whatever topic they're after. In case you ever get lost or con- fused, just type in "H" for help, and we'll immediately cut in with instruc- tions that should save the day. Besides, you can either ask ques- tions online through our Feedback service or phone our Customer Service Deparbnent. How to subscribe. To access CompuServe, you'll need a CompuServe Subscription Kit, a computer, a modem to connect your computer to your phone, and in some cases, easy-to-use com- munications software. (Check the information that comes with your modem.) With your Sub- scription Kit, you'll receive: ■ a $25 usage credit. ■ a complete hardcover Users Guide. ■ your ovm exclusive user ID number and preliminary password. ■ a subscription to CompuServe's monthly magazine, Online Today. Call 800-848-8199 (in Ohio, 614-457-0802) to order your Sub- scription Kit or to receive more information. Or mail this coupon. Kits are also available in computer stores, electronic equipment outlets and household catalogs. You can also subscribe with materials you'll find packed right in witli many com- puters and modems sold today I O Please send me additional inlonnation. I LJ Plcau! a-nrf me a CompuServe SuhBcriplion Kil. n I am enclosing my check (or l'!9,95, plus J2.50 tiandlitifi (Addiala tax if deliuemd in Ohiu) Please make check payable to CtjmpuServe Inbm^alion Services, Inc. n Charge Uiis to my VIS(VMas)erQird # tixpiralion Date Signature ■ Name, Address . City State , .'lip. MAIL TO: CompuServe* Customer Service Ordering Dept. RO. Box L.477 Columbus. Ohio 43260 pni-S04 I An HAfI BlDch Compviy EuyPUi and ELECTnONiC MALL an liKliinMrii) ul CanpuSgm, IncofpoTiiMl Travfllmoppflr t$ n »Qfvice niarh oP TWA A Printer For All Reasons Search For The Best High Quality Graphic Printer I If you have been looking very long, you have probably discovered (hat ihere are Just too many claiTns and counter claims in the primer market loday. There are printers that have somcorthefcaturcsyouwant butdonoihave others. Some features you probably don't care about, others are vitally itnportnni to you. We understand. In f^i, not lone njjo, wt wi;re in the .^me poi^itiun. Deluged by claims and counter claims. Overburdened by rows and rows of specifications, we decided to separate aii the facts — prove or disprove all the claims to our own saii.sfaction. So we bought primers. We bought samples of all the major brands and tested ihcin. Our Objective Was Simple We wanted to find that printer which had all the features you could want and yet be sold di- rectly to you at the lowest price. We didn't want a "close-out special" of an obsolete product that some manufacturer was dump- ing, so we limited our search to only those new printers that had the latest proven technology. We wanted lo give our customers the best printer on the market today at a bargain price. The Results Are In 'The search is over. We have reduced the field to a single printer that meets all our goals (and more). The printer is Ihe SP-1000 from Sciko- sha, a division of Seiko (one of the foremost manufacturers in the world). Wc ran this printer through our battery of tests aitd it came out shining. This printer can do it all. Standard draft printing at a respectable 100 characters per second, and with a very read- able 12 (horizontal) by 9 (venical) character matrix. This is a full bi-directional, logic seek- ing, true descender printer, •*NLQ** Mode One of our highest concerns was about print quality and readability. The SP-1000 has a print mode termed Near Letter Quality print- ing (NLQ mode). This is where the SP-1000 outshines all the competition. Hands dowTi! The character matrix in NLQ mode is a very dense 24 (horizontal) by 18 (vertical). This equates to 41,472 addressable dots per square inch. Now we're talking quality printing. It looks like it was done on a typewriter. You can even print graphics using the standard graphics symbols built into your computer. The results are the best we've ever seen. The only other printers currently available having resolution this high go for hundreds more. Features That Won't Quit With the SP-1000 your computer can now print 40, 48, 68, 80, %, or 136 characters per line. You can print in ANY of 35 character styles including 13 double width and 3 re- versed (white on black) styles. You not only have the standard Pica, Elite, Condensed and Italics, but also true Superscripts and Sub- scripts. Never again will you have to worry about how to print HjO or X^. This fantastic machine will do it automatically, through easy commands right from your keyboard. Do you sometimes want to emphasize a word? It's easy, just use bold (double strike) or use italics to make the words stand out. Or, if you wish to be even more emphatic, underline the words. You can combine many of these modes and styles to make the variation almost end- less. Do you want lo express something that you can't do with words? Use graphics with your te.\t ~ even on the same line, Vou have variable Une spacing of 1 line per inch to in Un- ity (no space at all) and 143 other software se- lectable settings in between. You can control line spacing on a dot-by-dot basis. If you've ever had a letter or other document that was jusi a few lines loo long to fit a page, you can see how handy this feature is. Simply reduce the line spacing slightly and . . . VOILA! The letter now fits on one page. Forms? Yes! Your Letterhead? Of Course! Do you print forms? No problem. This unit will do them all. Any form up to 10 inches wide. The tractors arc adjustable from 4 to 10 inches. Yes, you can also use single sheets. Plain typing paper, your letierlicad, short memo tonus, labels, tuiyihing you choose. Any size to 10" in width. In faci this unit is .so advanced, it will load your paper auiomati- cally. Multiple copies? Absolvuely! U.w forms (up to 3 thick). Do you want to use spread sheets with many columns? Of course! Just go to condensed mode printing and print a full 136 columns wide. Forget expensive wide-car- riage printers and changing to wide caniage paper. You can now do it all on a standard 8'/j " wide page, and you can do it quietly. The SP-IOOO is rated at only SS dB. This is quieter than any other impact dot matrix printer that we know of and is quieter than the average of- fice background noise level. Consistent Print Quality Most printers have a ribbon cartridge or a single spool ribbon which gives nice dark printing when new, but quickly starts to fade. To keep the printers output looking consis- tently dark, the ribbons must be changed quite often. The SP-1000 solves this problem by using a wide ('/j") ribbon cartridge that will print thousands of pages before needing re- placement. {When you rmally do wear out your ribbon, replacement cost is only $11.00. Order lt200l.J The Best Part When shopping for a printer with this quality and these features, you could expect to pay much more. Not now! Wc .sell this fantastic printer for only S239,95! You need absolutely aolhing else to start prinlinj; — Just add paper (single sheet or Tan fold Iractur). No Risk Offer We give you a 2-week satisfaction guarantee. If you are not completely satisfied for any rea- son we will promptly refund your purchase. The warranty has now been extended to 2 years. The warranty repair policy is to repair or replace and reship to the buyer within 72 hours of receipt. The Bottom Line Be sure to specify the order # for the correct version printer designed for your computer, Commodore C-64 & C-I28, Order «2(X), graphics interface & cable built in, IBM-PC and compatibles, Order iBlOO, plus 8' shielded cable m02. S26.00 Standard Parallel with 36 pin Centronics con- nector, Order #2400, no cable Standard Serial with RS-232 (DB.2J) Connec- tor, Order #2300, no cable We also have interfaces and cables for many other computers not listed. Call Customer Ser- vice at 805/987-2454 for details. Shipping and insurance i.s SI 0.00 — UPS with- in the continental USA. If you are in a hurry, UPS Blue (second day air), APO or FPO is $22,00. Canada, Alaska, Mexico arc S30.00 (air). Other foreign is $70.00 (air). California residents add 6% tax. The above are cash prices — VISA and MC add 3% 10 total. We ship the next business day on money orders, cashiers' checks, and charge cards. A 14-day clearing period is required for checks, /////'' Dealer inquiries invited For infornnatlon call 806/987-2454 TO ORDER CALL TOLL FREE 1 -(800) 962-5800 USA ,-, r po-j., 1-(800) 962-3800 CALIF, or send order to: ^PROl^K 1071 -A Avenida Acaso Camarillo, CA 93010 )Mmji (mMm%^^ April 1986 Vol. 4, No. 4 features The Winter Consumer Electronics Show Lance Elko 22 * Five Steps to the Right Printer Kathy Yakal 34 * A Buyer's Guide to Printers 42 * reviews Paperback Writer 128/64 Art Hunkins 48 128/64 Elite by Firebird Todd Heimarck 50 64 Ultima 4: Quest of the Avatar George Milter 56 64 Little Computer People Kathy Yakal 54 64 Also Worth Noting 60 64 games Dunk Kevin Mykytyn and Mark Tuttle 80 64 programming Turbo Copy A. M. Cutrone ._, 81 64 All About CP/M on the 128 Howard Golk 83 128 Directory Filer Rodney L Barnes , 87 64/+4/16 Windows on the 128 Jim Vaughan 88 128 BASIC Magic: Numeric Variables in READ and DATA Statements Michael S. Tomczyk 90 128/64/ + 4/1 6/ V Hints & Tips: Dice and Double PEEKs Thomas W. Wallls 92 128/64/ + 4/16/V Computing for Families: The Steven Spielberg of the 21st Century Fred D'Ignazio 94 * Power BASIC: Input Windows Thorpe Thompson 95 64 Machine Language for Beginners: Cracking the Kernai Richard Mansfield 96 128/64/V departments The Editor's Notes Robert C. Lock 6 * Gazette Feedback Editors and Readers 10 * Simple Answers to Common Questions Tom R. Halfhill 93 * Bug-Swatter: Modifications and Corrections 99 * News & Products 100 * program listings CQMPUTEl's Gazette Author's Guide 102 * How to Type In COMPUTEI's Gazette Programs 103 * The Automatic Proofreader 104 128/64/+4/16/V MLX 105 64 •^General, V=VIC-20, 64= Commodore 64, +4=Plus/4, l6=Commodore 16, 128= Commodore 128 COMrums CAZETTEh, publMn-J momhlv by COMPUTE) Publication-i, Int., SZ5 7lh Avcnutv Ni'iv Vork, *JY 10019 USA. I'hnm- (2r2) 26;.S3t,0. Editoriat officM are lt>i-,tttfd .ii 324 WtM Wi-niinvei Avtfniii', C.nfnsbnro, NC 274I1H. Ili.iiu-slic Bubicrptiilili: 12 Issues, 124. TOSTMASTER; Send 3Mll■'.^. rhanges to CO.Vf/'ti'J (■,'■* CM^ETTE. P.O. Biw Kt'lS?. Da Moitti'4, lA 50340. St^cond L.]J^.. ,ipplicdJion pending ,i( Grt^fnsboro. NC 27405 ,ind ,idt3itioisj[ nuii!in>{ o^Hcf^- i:nUrc contt'SUf* copyright (t;iyK6 bv COMPlfTEl PutilicllliJils, ]nc. Al] ri nb 1 V n-MTl'cd . 1 5 5N 0 7 1 7 ,17 1 h. COMPUTtt Publlcitiani, Inc. li plrt of ABC Coniumn Mlgixlnn, Inc. Onr of Ihe ABC Publithln); ContplniH: ABC Publithing, Finldcnt, Hubert C. Burtin); 13)0 Avmilf nl ihr Am.-iu.i. V.-w Vtifk, \^■^v 'li.-A Um D Payment enclosed (check or money order) □ Charge D Visa D MasterCard D American Express Name Address . City . Slate . Zip . I Ple»»e allow 4-6 week* (or delivery. COMPUTE! Publicationsjnc.^ One of ttw ABC Pudishing Corrponies COMPUTEI books are available in the U.K., Europe, the Middle East, and Africa from Holt Saunders, Ltd., 1 St, Anne's Road, Eastbourne, East Sussex BN21 3(JN, England. Editoi", and Readers Do you have a question or a problem? Have you discovered something thai could help other Commodore users? Do you have a comment about some- thing you've read in computeis ga- zette? We want to hear from you. Write to Gazette Feedback, computei's GAZETTE, P.O. Box 5406, Greensboro, NC 27403. We regret that due to the volume of mail received, we cannot respond individually to programming questions. Adjusting A Monitor 1 bought a 1 702 monitor for my 64, but I can barely read the letters on the screen. My neighbor has a 64 and a 1702 and the screen has perfect clarity. What could be wrong and where do 1 go to fix it? Grant French On the front of the monitor along the bot- tom is a control panel covered bif a hinged door. If yoij haven't alreadi/ done this, reach over lo the left side of this door and pull it down. Adjust the controls marked "bright" and "contrast" until the screen becomes more readable. If that doesn't u'ork, try switching the various RCA plugs that go into the monitor. The three rear connections provide better resolution than the two plugs on the front— tliere's a switch on the back that controls whether the input comes from the front or rear connections. If neither turning the knobs nor trad- ing plugs works, you may want to bring your computer and monitor over to your neighbor's house. Hook up your monitor to his computer and vice versa. You should be able to figure out whether the problem is the computer or monitor. There are Commodore Service Centers through- out the country; to find the one nearest you, call Commodore at (215) 431-9W0. Excessive Caution? I have two questions. First, some of the music and sound effects programs In my owner's manual do not work. Do you know of any misprints or do you think that my computer needs new chips? Second, is it true that if you POKE or PEEK a wrong number into the 64's memory that it could cause damage to the computer? Ron Calcagni 10 COMPUTEVs Galene April 1986 // a program you typed in doesn't work, either you made a typing mistake or the editors and programmers who put togeth- er the book or magazine made a mistake. It's highly unlikely thai one of your com- puter chips is broken, especially if it's just a few programs that don't run correctly. It's not unusual to make a typing mistake now and then. Imagine a medium - size program containing 50 lines of about 20 characters each, a total of 1,000 char- acters. Even if your typing accuracy is 99.9 percent, you may tnake a typing er- ror. In a computer program, a single char- acter can make the difference between a program that works and one that doesn't. Sometimes it's very difficult to find the typo, especially if you've accidentally en- tered a period in place of a comma, or a semicolon in lieu of a colon. The worst that can happen to a mis- typed program is thai the system will lock up. To escape from a lockup, just turn the computer off and then back on. You'll lose whatever is in memory (which is why you should save a copy of the program before you run it), but nothing has been harmed. You needn't toorry about a program mak- ing computer chips go bad. Nor should you be concerned about incorrect PEEKs and POKEs. A wrong POKE might make the screen go crazy or cause a lockup, but no permanent harm would be done. Don't worry about breaking your computer; the best tvay lo learn about computers is to ex- periment. If the machine starts doing strange things, turn it off for a moment. The most you can lose is the progratn in memory. If you've doubiC'Checked your typing and still can't find anything wrong, there may be a typo in the program listed in your book. In general, most publishing companies and software /hardware manu- facturers support their products. If you write a letter to Commodore, they should be able to inform you of any corrections lo programs published in their books and magazines. Likewise, if a program from the GAZETTi; doesn't toork correctly, write to us, indicating the program name, when it loas published, the error message, and line number. If we know of corrections, ive'll let you know; if not, we'll send a let- ter indicating that the program works. And if your ABC word processor, DEF in- terface, andCH! printer don't work prop- erly together, send a letter to each of the manufacturers. At least one of them should be able to give you some answers to your questions. When writing to a hardware or soft- ware company, give as much information as you can. Indicate the equipment you own, what exactly is §0111^ wrong, what you've tried, atjd so on. It's better to give too much information than not enough. Extras Required 1 am using "X BASIC" from the October 1985 issue to write a program. If 1 were to send it to you as a submission, would you accept it? Or would 1 have to write it using the regular Commodore BASIC? Matthew Kaeser When you're submitting a program for publication, it's safest lo stick to Commo- dore BASIC and machine language. The appeal of a program that requires "X BASIC" is limited to readers who own the October issue and typed in the program. We assume that most readers who type in progmm listings own a computer, either a tape or disk drive, and a joystick or two. Although we don't autojnatically reject programs that need extras such as X BASIC, Simons' BASIC, the Super Expan- der, light pens, Ham radio equipment, voice synthesizers, 8Q-column cartridges, and the like, a submission that requires additional hardware or software is less likely to be accepted than a stand-alone program. Noise And Randomness What is a checksum? 1 have asked com- puter teachers and they did not know, so I am writing to you. I need to know in order to use the "MLX Machine Lan- guage Editor." Evan Resnikoff A checksum is a way of filtering out static, a way of foiling entropy. Let's say you call a friend in Australia and say "It's sum- mertime, isn't it?" Because of noise on the line, she hears only "...time. ..is. ..it?" and replies, "Three o'clock," The message sent from your side was OK, but it deteriorated on its way through the phone lines and was interpreted incorrectly. The same kind of misunderstanding can occur when computers are sending or receiving information. A wide variety of formulas are used, but the basic idea is the same. The originating computer outputs .,;-ji,f.r.-'>,- 11/16. weighs 9 pounds. Programmer's Tool Kit *^^ ^_ pt-oi *a9»95 Contains programs, and BASIC source listings for reading the Melo- lian Musical Keyboard, and for reading and creating music files for VIelodian ConcertMaster. ConcertMaster Software cm-oi $29*95 ConcertMaster teaches how a composition is put togettier. note by nole. instrument by instrxjment You learn lo play ss pre-recorded songs from Bach to Rock Then you can compose your own songs and record them right onto your floppy disk, ConcertMaster Teaches: Scales, Bass lines, t^amiliar Beginner Songs such as "Jingle Bells", Easy classical songs such as "Bach Minuet" and Ravel's "Bolero". Advanced classics like "A Midsummer's Night Dream" by Mendelssohn. Popular hits such as "Thriller". Instruments Sounds Organ. Tnjmpel, Flute. Clarinet. Piano. Harpsicord, Violin. Cello, Bass, Banjo. Mandolin, Calliope, Concertina, Bagpipe. Synthesizer 1, Synthesizer 2, Clavier I, Clavier 22, which can be played over a ^octave range. Programmable sounds as well. Recording Functions: Three track sequencer (recorder) with overdubbing and multitimbral (different mstnjment sounds at the same lime) effects. Each track can be set to one of seven different functions: • Monitor] Lets you use a track to play music live, without recor- ding it • Rccordt Records a track as you play. • Playback: Lets you hear whatever has been recorded or load- ed into the track. You may playback one track while recording another to build layers of instruments, • Mutci Turns a track off This is useful when you want to listen to or record one or two tracks at a lime. • Savci Stores a track to the disk, • Load I Loads a track from the disk, • Protect; Write protects a track. Create Nev(r Instrument Sounds Choose from pulse, sawtooth, triangle and noise sound sources. Con- trol the sound envelope with attack, decay, sustain, and release times. Ring Modulation and Syncronizalion effects Set Low pass, band pass, and high pass filter frequencies, ConcertMaster Requires: A Commodore 64 or Commodore 12a with disk dnve, Melodian Musical Keyboard kb-oi is required to study the reading and playing of musical notes. Melodian ScoreMaster * — — -*— sm-oi $29* 95 With the ScoreMaster program your music can be pnnted out in mustc notation, which other musicians can read and play. Any music recorded with the ConcertMaster program can be printed by ScoreMaster, ScoreMaster Requires: A Commodore 64 or Commodore 128 with disk drive and printer compatible with the Commodore graphics mode such as the Com- modore MPS 803, 1515, and 1525, Melodian ConcertMaster program ACCESSORIES Headphones $12.95 Stereo Cables $ 9>95 Demonstration Disk $ 9.95 RECORDINGS Christmas Carols.. $12.95 Tchaikowsky Nutcracker $12.95 Bach's Hits $12,95 Classical Favorites $12.95 FOR CREDIT CARD ORDERS, CALL TOLL-FREE 1 -800-327-4566 IN FLORIDA, CALL 1-800-35-I-8777 'orour lnt«ntatJortalcuitafnar«iPioase send crediE card number or international monav c>rder 1 U S dollars, Of call 30a-fi7S-JT77. For Canada and Moxico, udd 115.00 lor ^tt m&v\. Overseas dd Sl&.OO lor surlact^ Tinii, .ind S70.00 for air mail, ■■■ ■■■ ■■■ >BP «■■ Abb •■■ *■« ■•« •«» «•• »*■ •■■ •■« ■ ■■ ■•■ ■■« •*«•••■ •»■ ■■■ ••■ »k* ha* •'■» ■«• *■« ««• *N« «*■ ■•■ •>« »•■»•>■■ MMm ■•■ »•« ■•» ifeB ■«■, «■■ ■.»• <•» ••• • •> •*■ •■• ■•■ *•« »«• ■*■ ■>> pgp ««« ■■#*•*• *■■ p.»« ■ •a ••■ ■■■ ■•■i»iii •*•■* «**■■>« ■■■■•■• ■•* iifebaKiB ■«> >>■ TM The new, fast vtfay to learn, play and coint>os« mustc. 'D 198S, Molodian, Inc . 970 W, McNib Ra . Fon LauderdalorFL 33309, All rightB fesarved MPS-803, 1 get the inverse of what is on the screen. Also, I want to print screens from commercial software. When 1 try to add the screen dump, the commercial program locks up. Zack Stonich The individual dols on a hi-res screen are called pixels, each of which can be either on or off. The color of each 8 pixel by S pixel section of the screen depends on the corresponding value in color memory. Within a standard hi-res screen dis- play there are two colors available, the foreground color for the pixels that are turned on, and the background color for lunied-off pixels. Srty you set the fore- ground to red, the background to white, and then draw a triangle on the hi-res screen. A red triangle would be displayed on a white background. Switch the col- ors—foreground to white, background to red—and the result is a white triangle on a red screen. Either way. the triangle is displayed in the foreground color. In a hi-res screen dump to a black and white printer, you would want the dark screen colors to be printed and light colors not printed. But most hi-res screen dumps read the screen to determine where individual pixels are on or off. Regardless of whether the screen displays a red trian- gle on white oraiohite triangle on red, the image sent to the printer is a black trian- gle on white paper, if the foreground color is lighter than the background, the printed picture will appear to be reversed. Here's a suggestion that might help. If the hi-res screen is located at 8192-16191. add this line to your program: FOR J -8192 TO 16191: POKE] ,2SS -PEEK(J); NEXT The screen image will be reversed, because all the on pixels are turned off and vice versa, but the screen dump will print correctly. There's no easy answer to the second question. You probably won't be able to print screens from commercial games. Al- most no games allow you to stop the pro- gram, load another program, and then resume play. Even if you could, there would always be the potential for a memo- ry conflict. If the commercial program and the screen dump program both tried to use the same area of memory, one or the other wouldn't work correctly. What you would need is a completely transparent screen dump program. If you're using a graphics program, XfOU may be able to save the hi-res picture to disk. If the documentation includes information on how to load the hi-res screen back into memory (for use in your own programs), you could follow the in- structions there. Once the hi-res screen has been restored, you should be able to use the screen dump program. Reading The Directory I am writing a BASIC program that reads the disk directory. I'm interested in how you would assign the filenames and lengths to variables. Lorene Heffernan The following program reads the disk's di- rectory and displays it on the screen: FC 10 OPEN 2,8,0, "5" SK 20 GET#2,A5:GET#2,A5 KF 30 GET#2,L5 :GET#2,L5:IFST=6 4TiJENCLOSE2:END 1X3 40 GET#2,LBS:GET#2,HBS;I,N=A SC{LBS + CHI?$(0) }+256*ASC{ HBS+CHR5(0) ) HX 50 PRINT LN; SD 60 GET#2,A$:IFA5=""THENPRIN TCHR5{13); :GOTO30 RX 70 PRINTA5; :GOTO60 The directory file, under the name "$", can be read like any other file on the disk. Since it is a program file it should be opened with a secondary address of 0 (line 10). The first two bytes of a program file are the lou' and high byte of the start ad- dress; these are unnecessary for our pur- poses, so they're read and ignored in line 20. Every line of a BASIC program is made up of four parts: the line links, the line number, the body of the line and an ending zero. In line 30 the line links are read in and the reserved variable ST is checked. If the end of file has been reached, the file is closed and the program ends, To use this routine in your own pro- grams, replace the END command in line 30 with a GOTO (or a RETURN if you're using it as a subroutine). Line 40 reads the loio and high bytes of the line numbers, then calculates the value and prints it on the screen in line 50. It's really the number of disk blocks used, not a line number. But remember that the directory is treated as a program file, so the blocks used are treated as line numbers of a BASIC program. The rest of the line is read, character by character, until the end of the line (0) is found. Once the end of the line is reached, the program prints a carriage return, to separate the lines, then goes back to line 30 and repeats the process. To assign the filenames to variables, concatenate the characters into a string after the GET#2,A$ in line 60. Custom Characters For The 128 I have been able to redefine characters on my Commodore 64 but have not yet been able to do so on the 128. I'd like to know the equivalent addresses {such as 5372, 12288, and the keyscan interrupt) for 128 mode. James Go well The following program redefines the @ symbol into a "C!" character. The pro- gram takes about 25 seconds to execute. KE 10 POKE 2604,30 DJ 20 POKE 2 17, 4: FAST RX 30 FOR A=53248 TO 55295 :BAN K 14:B=PEEK(A) :BANK 0 : PO KE A-3a912,B:NEXT!SLOW PH 40 FORA=14336 TO 14343 iREAD B:POKEA,Q:NEXT QQ 50 DATA 98,146,130,130,144, 98,0,0 Location 2604 is equivalent to 53272 on the Commodore 64. It controls the text character dot-database address and the video matrix base address. Bits 3-3 con- trol where the character set is found. For this example we'll put the character set beginning at location 14336. Because this is in the section of memory normally used for BASIC programs, it is prudent to pro- tect memory by entering GRAPHICl :GRAPH1C0 before running the program. Bit 2 of location 217 controls whether character data is read from ROM or RAM. Normally this bit is set to 0, which means all character data is read from ROM. In order to create a custom character set this bit must be set to 1 by POKElng location 217 with 4. It's not necessary to disable the key- scan interrupt: the BANK command al- lows you to access other portions of memory. Line 30 is used to copy the char- acter set down from location 53248 in BANK 14 to location 14336 in BANK 0. A much faster method to copy the normal character set to location 14336, es- pecially if you own a 1571, is to use BSAVE and BLOAD. First, save the char- acter set with BSAVE'CHAR- ROM",B14, P33248 TO P55295. Then, to load the characters into 14336, put BLOAD "CHARROM",B0,P14336. Line 40 reads in the data from line 50 and POKEs it into the area reserved for the definition of the @ symbol. Splat Files In the directory of a certain disk are two files that have an asterisk next to the file type (PRG or SEQ). 1 can't seem to load either of these programs. Why is this? Tracy Austin If they're sequential files. It jneans you did not properly CLOSE the file. If they're program files, they loeren't completely saved; perhaps you removed the disk from the drive before the disk drive finished writing the file. These files marked by an asterisk were once called "poison files." Newer versions of the disk drive manuals now refer to them as "splat files." At least part of the file is gone and cannot be recovered. Whatever was in the buffer at the time the save /write opera- tion was terminated was not written to disk. The best thing to do with a splat file is to remove it from the disk because it can interfere ivith other files on that disk. Don't scratch a splat file; use the 16 COMPUTEts GazBtta April 1986 am Now Get Inside Your Commodore with COMPUTErs Gazette Disk. Now there's a way to get all the exciting, fun-filled programs of COMPUTBrs fiazetfe-already on disk— with COMPltTEl's Gazette Bisk. Subscribe today, and month after month you'll get a new, fully- tested 5V4-inch floppy disk guaranteed to run on your Commodore 64, Commodore 128, or VIC-20 personal computer. COMPUTEl's Gazette Disk brings you all the latest, most challenging, most fascinating programs published in the corresponding issue of COMPUTEVs Gazette. So instead of spending hours typing in each program, now all you do is insert the disk... and your programs load in seconds. RESULT: You have hours more time to enjoy all those great pro- grams which appear in COMPUTERS fiazefle— programs like Number Quest, Address File, Treasure Hunt, Castle Dungeon, Vocab Builder, SpeedScript, and hundreds of others. 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Just tell us what you want to buy, and what you want for free. It's simple. And there's a 14-day "satisfaction or your money back" guarantee on all products ordered direct. In case your participating dealer runs out of "Get One Free" coupons, use this. n Yes! I want free software from Electronic Arts! D No thanks. I'm using my computer as a doorstop. (Check one) Apple II, 11+. //c, //e n Dr.J.&. Larry Bird Go One-On-Ontj □ Archon n Finnncinl Coiikbook □ Music Construction Set D Pinball Construction Set □ Seven Cities of Gold D Archon II : Adept n Movie Maker Commodore 64 & 128 Atari 400-1200 series n Dr J. &. Larry Bird Go One- On- One D Archon n FinancinI Cookbook n Music O)nstriiction Set n Pinball Construction Set □ Seven Cities of Gold D Archon [[ : Adept D Movie Maker DM.Ul.E. n Realm of Impossibility n Mail Order Monsters n Racinj; Destruction Set D Dr, J. &. 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