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ARTERIAL 13 DP THE PUBLIC. DUNST

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PERSONNA BASICARE SYSTEM

HELP! HELP!! Can anyone help me with information on how to use a PERSONNA ZX81 BASICARE system, I

have the Personna, Minimap, Pericon C, Sonus, and RAM16 modules. to be minimum documentation system, and I'm lost. I would appreciate

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Nov. -Dec , 1985

NEWSLETTER INDEX

NON-CLASSIFIEDS PG 1 PRESIDENT'S MESSAGE PG 2 TEXT MANIPULATIONS PG 2 SINCBITS PG 3 ZX81 NEWS PG 4, 5 TELECOMPUT ING PG 6, 7 TAPE AMPLIFIER PG 8 LARKEN DISK SYSTEM PE 8, 9 2068 TIP NOTES PG 10 MODEM WOES PG 11 TELECOM TREATS PG 12

FOR SALE - TS2068 Computers $150 ea. - 752040 Printers $60 ea. - A & J Microdrive & I/face $159 = Rotronics Dual H/drive $175 i = Rainbow Emulator tS 0 - lafadrive Wafers =-

from anyone who has such a system, with a view to three sizes 34 ea, sharing information,tips,etc. on its operation. Contact: My address is: Evelyn Memillan, 5851 Pt. Pleasant Heil Naragno

Or., Halifax, N.S. Canada, B3H 187

TORONTO TIMEX - P.O. Box 7274 S

325 Woodward Avea, Hamilton, Ont., L3H 574

SINCLAIR USERS CLUB tn. A Toronto, Ont., MSW IX9

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PRESIDENT'S MESSAGE

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With the start of the Christmas season I like to extend to all our members

to our newsletter contributors a

Joyous Christmas,

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With the help of many of our members concluding a very successful year in our c

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MASH!

Have a MERRY CHRIST

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Tam Robertsona tospuserve 72157,3401 FIIO Net iii/Nnde 408

UPBATES: The revised Larken DOS iepros) has been delivered tn our members, who have this system, and the concensus is - ‘it works like a charm, all the bugs are gone’. Remember, this is (the only) system compatible with the Spectrua! So auch so is fact that George Chambers has SCRABBLE on disk!! Now that is a long program! The November issues of all the UK Sinclair related »agazines are carrying pictures plus descriptions (hands-on) of the new Sinclair 128, Needless to say it has 128k and is Spectrum 48k compatible. Before you rush to your credit card to purchase one, be advised that it is preseatiy being sade and sold in Spain only. Sinclair is also supposed to be readying a 1924k computer called "The Enigua’, which will have two 3.5° drives built in, all the 8L bundled pragraas on ROM and a printer and RGB monitor, retailing in the 300 to 1000 pounds range, Í have just received the Zebra 05-64 cartridge and mill evaluate it over the next few weeks. At the moment it looks like à creat idea, BUT, nobody seems to know how to take advantage of the 44 column ande it provides, Now that the dL price has dropped ta $299.00 (US) maybe more of us will be gning is» that direction. Think about all that great bundled software!

T87048: I finally made the plunge and am now a full fledged wesber of the disk-drive-comaunity. I bought the RAMEX/Amdek III system from Ramex International Ltd. 17620 26 Wile Rd. Washington Michigan 49094 (315-781-5500). The price is $259.00 (US) for the COMPLETE system, which includes the DD iaterface, cables, utility disk and the Amdek III drives. The Aadek III comes completely encased with two 3' Hitachi model FI305S drives, power supply and a fan. This system uses SPDOS, by Abbeydale Designers, which is also used in the UK by Vatford Electronics and by Keapston (latest eprom version) in their DD intertaces. After formatting the DODS diskettes I have 184k useable on each side, Like the Timex Portugal system, each drive has only one disk read head and the diskettes must be flipped aver by hand. Not too had a price to pay, al] things considered! With the invaluable help of David Ridge 1 am becoming fairly DD/computer literate. Mow it is not that this systes is difficult, it is simply that I have never used a DP before. My only comments are! (1) "HOW LONG HAS THIS BEEN GOING ON?" and 12) "I CAN NOW DO SEVERAL THINGS, WITH THE COMPUTER, IM THE SAME TIME IT PREVIOUSLY TOOK TO 20 ONE, WITH CASSETTE!", For exaaple, to use Loader IV, Tasword II and Mtera to upload/download files, with the 2050 andea, was a tedious task which could take up to 30 minutes, if an error Was Bade in the file and it had to be edited out after loaded into Mtera. Now the same thing takes less than 5 minutes (at the aost). See how it allows the user to perfora more tasks in the same tiae period! I can not say enough good things about this systes as it has enhanced ay computing tise and abilities in a aost positive manner, The only negative aspects of this system is: (1) the DOS occupies RAM from 48999 to 53599, and (2) the documentation should be iaproved to cover all asperts of this system in a aore "user friendly” aanner. I understand both of these itess are being addressed by Ramex and by Abbeydale Designers. In the meantime our resident genius,

SINC-LINK NOV/DEC 1985

p (€ i a i ai ene RSA Deer CONFERS at A Ir PIA oA A i r = AATE rns Manne MN a ni a e a LE TEN ienaam medi REN = m iud

David Ridge, is working on a utility to bypass this RAN

situation.

SPECTRUM! Latest Spectrum hardware item is the ANX NOUSE, which comes with 4 pieces of software at the astronomical price of #80 (pounds sterling], Already there is an ARTWORK type program which is reported to be compatible with it. Look for THE ARTIST (version 2) to also have a 'rodent-of-sorts* compatible with it! My 2 microdrive became so noisy (obviously very bad @A at Sinclair) that I had to return it to Sinclair (under the one year warranty of course).We shall see if their serviet is as bad aS everyone Says it is! OCP has a new word processor on the market that is getting 5 star reviews, It is the "WORD MANAGER” and retails for approx. $13.00 (pounds sterling). It cam even be purchased on disk - how TS times are a changing! Bob Dyl, of THE ENGLISH MICRO CONNECTION 15 Kilburn Court Newport RI 02840 (401- 849-1805) carries this program and all other good Spectrum and QL software. Call first as he does not take plastic, I cannot remember Bnb's price on this as this was only nne of the many items we talked about in cur last 20 ainute telephone call. Bab also carries 2 very good Spectrum DD Interfaces - the BETA at $159.00 and the KEMPSTON at $120.00 [5130.00 for a 2088 version edge connector), both are US prices, The BETA has a switch to "save to disk’ and only uses 128 bytes of RAM. They also work with the AMDEK III drives. As a bonus the BETA is coapletely compatible with Interface 1. Think of it - use either disk drives, mirrodrives or cassette, as you require! These DBI’s are definately worth thinkiag about if you "Spectrumize' sore than you use the ‘as is’ 2048. Again, before you buy talk to Bob Dyl.

GL: With the advent of price cutting this computer is starting to sell in large numbers, I just read that Sinclair is producing 5000 a week and still cannot keep up with the demand. This means that the Hardware and Software people are getting more aad more involved, because now they can sell in quantity. Bob Dyl is selling a combination DD/Centroaics interface with 128k resident RAM for $289.00 and will be getting a 254k ‘internal’ add-on RAM, which goes inside the 8L, not stuck on the left side like the others. So, with this additinal memory plus the combination DOI/CPI you would have a 512k GL complete with “bells and ahisties". Total price you ask - why it's $299 t $289 + $179 - for a total of $767.00 (US). ALI you add is “LOVE” and a mOhitor (plus Canada Custoas and delivery of course).

EDITORIAL COMMENT: Our "WORLD OF TS COMPUTING" is bigger and better than ever! Witness the new Sinclair products forthcoming, the pricing and the hard/software support, Who could have imagined, back in Jan. 83, when I bought my first TS1000 that a Timex/Sinclair system would have disk drives, a modes, an 80 column printer, graphics tablet, a Spectrum Mode, RGB sonitor plus the "thousands" of programs available, 1 as = truly impressed!!! Even the 64k 1000 now has a disk drive, modem, 80 rolusa printer, JLO video upgrade, a 44 column screen and tplour!! With the increase in business software, telecommunications capabilities, word processing capabilities and a general improvement in programming techniques, we have one of the "BEST, MOST COST EFFECTIVE SYSTEMS ON THE MARKET". Remember that, the next time someone says something disparaging about OUR SYSTEM.

Page 3

BOS NEWS #5 IN A SERIES BY PETER M*MULLIN

ure files when you're having fun. lugh!) The festive

be upon us by the tiae aany af you read this.

happy Yuletide and a promising New Year! Hope you

E instalment for 1785. In view of last aanth’s , D promised to keep this intro short. It was.

ui m

xx BUG ALERT ** BUG ALERT ** Dwnerz of AEREO CP-IX Vers. 2.2 Centronics interfaces please take note. The SERCO CP2,2 RON has, in addition to an ASCH printer driver, a Disk Boat routine patched into the machines’ initialization. On power-up, it checks far an AERCO Disk interface, and if there is one, it praceeds to load the Directory page from Drive A. 1f there's no Disk system, the initialization continues, and up comes 9/0 (!), This is because during the Disk? check, the CP2.2 actually forces the machine ta execute a BASIC line embedded in the EPROM code. Thus, the sachine comes up with a 0/0 instead of a K cursar, To the goint: in the gidst of this exotic initialization scheag, the CP2,2 somehow sets up addresses 1450/7 and 18508 ta hold a critical status flag far the operating system. Tu the normal 24/75 ROM, these two bytes are completely unused and ignored. They frequently get used as a “cache-all” register by many Machine Code prograns (e.g. HOT-2, IXLRB8, & many “toglkits"). The problem is, with the CP 2.2 interface attached, ANY PROGRAM which loads in from tape with values other than ? in 15507/15508 will crash if you try to BREAK it. Even if a program loads in with these bytes OK, if it changes their value at any time, you are probably out of luck.

Some programs which exhibit this problea can be "cured" by loading the program without the interface attached} Break, then POKE 15507 and 15508 with 0, and re-SAVE the poked version ta tape, The new version should now LOAD land Break) GK with the interface attached.

AERCO now have available an improved version af their CP-ZX Vers, 2.3, which they claim has the problem eliminated, u have a 2.2 or earlier version of the AERCO 1X CPI, you d plies about getting an updated version (either free very nominal price) froa AERCD, 7608 Robalo Rd., X 78737.

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HARDWARE USER REPORT 3**

SUBJEE E The JLI Video Upgrade Project, available from The Jahn L. üiiger Co.,

11491 Whi dhey Dra, Cusberland, IN 4422?

INTRODUCTION: Since Mr. Qliger manages to keep quite busy without doing any real advertising, a lot of füiks are unaware af the fine products he has available for the 2481, A certain mystique has built up around JLO products, which I hope ta dispel. Yes Virginia, dohn Qliger is a real person, who

answers gail, ships orders on a realistic schedule, and has some pretty neat ideas.

& RESOURCE T SINC-LINK VOL.3 NO.6 DEC/8S

t sort of peripheral is this Video Project? Let me in with a sweeping analogy: the Video Upgrade Project is t like a video annitor, a disk interface, of a fullsize nter, Once you jon up a monitor and get used to it, the just won't do anymore. When you get a disk driva, you madly transfer all your software, and then avoid cassettes like the plague. When you get a real printer, the 2046 generally becomes a hi-tech paperweight.

Likewise, after having the Video Project (VP from here an) for a couple sonths, I loathe going back to the flashing, flickering snail’s pace of "noraal" video which I have lived with for so long.

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WHAT IS IT? Remember the ill-fated Kolorworks board, and the Colarsingi? Beth were color video boards for the 2181, which never really hatched due to various impracticalities. The JL VP surpasses both. It is elegantly siaple, thug economical. The firmware integration ta BASIC reflects the same qualities, and is virtually transparent to 994 of existing software,

The VP consists af 2 circuit boards which plug the back of your compuler, These boards edge connection only, and are meant to plug into a antherboard. Coapatible motherboards are available from JLO, or from Maplin or Eprom Services in the UK,

Viden Board "A" halds a Texas Instruaents THS?P18A Video Display Processor, 16K of dedicated Video RAM, and 1 decoder chip. This video RAM does not occupy any of the 290’s address space- the 280 communicates with the VOP & videa RAM through 1/0 parts 3F & 7F.

Video Board "B" has sockets for two 2764 (86) EPROMS, and 4 decoder chips. Eprom "A" is @apped ta the O-BK area, and overrides the internal ROM in your computer. It is identical to the 7X BASIC ROM, except for the parts which deal with generating a video diplay. All the real work is now done by the YDP. The 180 just sends it the necessary data and is free froa the actual task of generating video.

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WHAT DOES IT DOG? Two advantages which are immediately apparent are speed, and continuous display. In SLOW ande, the computer is now alanst as fast as in FAST ande. In fact, it can be difficult to tell which sade you're in at times. In FAST ande, the display doesn’t go blank. It just resains static until you come to a PAUSE, INPUT, or SLOW command. There is absolutely no screen "jusp", flashing, or flickering, at all, in either SLOW or FAST mode. Entering and editing BASIC prograas is a real pleasure, especially in FAST anode. The ald screen reformatting games of the I181 are qone! When you Enter a line, it singly (zap) appears in the listing. LOAD and SAVE are rather interesting. When you enter a LOAD ar SAVE command in FAST gode, the command stays on the screen through the tape operation, SAVE and LOAD activity is shown by the border rapidly flashing through a sequence of 14 colo effect is similar ta that of the 2048 LOAD & SAVE patt How about software compatibility, kit building de the bottom line?

PAGE 4

ZX¥81 NEWS & RESOURCES SINC-LINK VOL.3 NO0.56, DEC. 85

SOFTWARE COMPATIBILITY: As mentioned, the JLO VP is compatible with just about ail software. The main exceptions are fast machine code arcade gases, like Frogger, Pac Rabbit, etc. They run, but so fast they’re generally impossible to play. By the sane token, zame games that were boringly slow before are now a real challenge, Psion Flight Sisulator now responds like a iet fighter rather than a Cessna. Mazogs is siaply a hoot. BASIC programs with lots of calculations or plotting really Benefit, toc, The only software I have found that's truly inceapatible with the VP uses software-only seans to simulate hi-res with the standard machine, or tries to peek the character generator of the ROM to get pattern data, This includes games like Forty Miner, Sea Mines, and 2Xtricator, and utilities like N. El@aleh’s SW HI RES and Callisto’s Sraphica. fou simply have to unplug the video boards and use standard video for these programs.

AVEATS, THE BOTTOM LINE, ETC.: The Video Project, as the nane iaplies, is available oniy in kit fora. You may purchase either just the bare circuit boards with instructions, or get an lalmast) complete kit of parts. For $48.95 U.S., you can get both boards and ali parts except far the actual VDP chip and its crystal, The TMS97i8A VDP chip is available from several parts suppliers at widely varying prices. The best I’ve seen is $9.95 from Jaseco Electronics, in Montreal, The 10.7385MHz, crystal is also generally available for about 18,00, When you order a VP kit, JLO will include a listing of the current best sources for the VBP & crystal. By the tine yau account for all the tidbits, allowing for a actherboard if you don't already have one, etc., this whole thing is roughly a $100,00 proposition.

The kit instructions are complete and reasonably clear, but I really can’t recomend this as a first-time project for the prospective kit builder. You aust he able to do very fine soldering on these circuit boards, and some familiarity with good electronic assembly & soldering practices is truly an asset, My only complaint is that, for sconomy’s sake, the tesdthrough holes on the double-sided circuit boards are not plated through. This means you aust solder in a healthy nuaber sf tiny sire ‘eedthreugh conductors before mounting any parts on the circuit boards. Believe ae, this is a tedious and tine consuming task, after which soldering the actual parts in plate is a breeze.

A ainor acdification aust be done inside your computer to permit functioning of the VP, The NMI line between the ULA and the CPU aust be cut, and a dinde and resistor added. This is very sisplg to do, and does not affert the normal operation of the computer. This aod is much easier ta do on the older Issue 1 2331 boards than on the later Issue 3 layout.

Last hut not least, you must supply and program your own 4 54 EPROM for the aodified operating systes. Mr. Dliger will upply a tape for his 2764 prograaser, which contains the necessary code and will automatically program yaur new EPROM. lost af the cade is gotten from your resident ROM, so if you have, for sample, Tom Bent's SK ROM UPGRADE, all the lapravenents in it will also appear in your new video ROM,

John Oliger has kindly put his operating code in the public domain. If you don't have an Eprom prograsger, don't despair. Tom Bent will supply the VP EPROM with his Yers.1Q ROH improvements: as well, for $25.00. 1 can supply a VP EPROM based on the T81000 ROM for $10.00, to cover cost af the EPROM and postage, In either case, you must specify whether you want 15K or &4K RAMTUP initialization, default paper, ink, and border colors, etc. That's the lazy way cut, though, An EPROM programmer is a really handy gadget to have around, and represents a aodest investment. JLÜ's programaer is a snap te asse&ble- it uses plated through holes. Building up a motherboard & EPROM programmer is good practice- it'll sharpen up your soldering skills (and confidence) before tackling the Video Project. And you'll learn a lat more.

ADVANCED FEATURES: So far, We've discussed only how compatible the VP is with existing software, By executing certain RAND USR coamands, you can choose hatween normal IX characters, or lower case instead of inverse on the screen. The old system variable MARGIN is now the COLOR system variable: you cai poke different values to this address to select INK and PAPER fron {4 different colors. That's the limit of the extra comaands available from BASIC, but hy using aachine code to communicate with the VDP, it is capable of 32, 40, or 54 coluan screens, true hi-res colar graphics which are in some respects superior to 2058 graphice rapahilitiss, end real sprites, definable on 32 differant planes! In addition to this, the VP removes virtually all the funny display-dependent limitations of the machine. Minor modifications will perait machins code ta run anywhere in 64K, and even Mode 2 interrupts can be used. For machine code programmers, the IX register is now available for use, and the R register is used in the noreal 780 fashion, Ne limitations exist on the location of OFILE in RAM, and illegal" characters fi.e. tokens) can even be poked inta the DFILE without causing a crash. Since the character patterns are stored in video RAM rather than in ROM, it is possible to have progrags load in with user-defined character sets- excellent for games and wordprocessors. l'a now running Word Sinc II.3 with upper and lower case onscreen, as well as special symbols for control characters. Prospective software support is exciting, too: Silicon Mountain Software now have a tape version of Memotext with a 44 col. onscreen viewing option, as well as a &4-col. hi res color extended BASIC for release in the not too distant future. And Callisto Software will be producing an exotic graphics toolkit for use with BASIC, as well as a hi-res screen, color version of Sinc-artist!

IN CONCLUSION: The JLO Video Upgrade Project is an extreaely well conceived and executed product. For the 2%81/781000 hobbyist, this is an excellent opportunity. It gives you speed and video capabilities at least equal to the 2028 {the video is actually MUCH aora stable), and iaproves the perfarsance af aost existing saftware. You get SUPPORT, too. If you can't get your kit ta work, you can send it back to JLO along with $15.00, and he will locate & fix the problea for you.

FEATURED NEXT ISSUE: THE AERCO FD-IX FLOPPY DISK

PAGE 5

197/23/35 - Wed

TELECOMPUTING 5 by David C. Rig First I would like to citar us s couple of Bees

that in lazi ticis lI told you 2 r2ed to = t xcept = ts iain sigi! sorry

a You Simply type GO LUE at any <1) prompt and you ill be taken to the land af

the orphaned computers. Aisa I

n

mentionez that a one year sabzcmription to AN LINE TODAY magazine is included with your

gs. CompuServe starter kit, The subscriotion is actually free for as long as you are an active user. Ok, you’ve all been crying "where’s the beef!" sa in this article we will learn a little maden magic. Nothing up my sleeve...herse we go! Certainly the most misunderstood and poorly documented aspect af using the Westridge 2940580 modem is the area of sending and receiving programs, especially machine code. Before I get into that area however I think I should first clear up the confusion surrounding the parameter settings for your modem. I will "at give an in-depth explanation of what Duplex, word size and Parity mean as that would require much more space than we have here and besides even I'm not totally sure what some of the details! Instead I will simply give you the settings that you will need for the vast majarity of your telecommunicatinsg. iI have found that the almost inivergsel settings for communicating with any BBS are as follows:DUPLEX-full, CR-off, F-off, CON-none, STOP-1, UOFRD-7, PARITY-even. Experience has shown that these settings Thay not be the best for other madems (although I don’t see way not) but will work just fine for the Z959g. The only time these settings need to be

Fy. 6

changed is when ,ou are communicating directly with another micro such as another 2682S user or when you are Sending/receiving a program, or when the BBS that you are connected to recommends different settings. Bare in mind however that T have found that even when they do recommend different settings, the ones described above work just fine.

When you are cannected to another micra, your Parity must be set to odd and tie dunlex ta half, While we are an the subject of micro to micro madening, I should mention the easiest way of accomplishing the connection. The simplist wey that I have found is ta first communicate with the other person by voice. Then both of you should enter a MODEM CMD M (caps shifttenter while in the terminal mode) at the same times. Do not hang up the phone at this point. When the screen tells you that you are connected, you may bath hang up the phone. At this paint, anything that either of you type will appear con both screens!

Now if you are sending a BASIC program, you must go ta the data buffer menu and empty the buffer then change ta CON: HEX. Next get back to the main menu and exit to BASIC. Load the program just as you normally would. When loaded, cail up MTERM with PRINT USR 34916 and connect with your party as described above. Make sure that the person you are sending to has their CON:HEX and the buffer is empty. The receiving party does not have to open the buffer manually. I vill show you how the sending party can do this. ünce you are both Communicating on screen, the receiving party can sit back and leave the driving to the sender,

The sender will now open the buffer af the receiver by

sending a gontrol "R". As decribed in the MTERM manual, a gontrol character is invoked by first pressing caps shitt/7 and then thz desired letter. After openiogs the receiving buffer, go to your data buffer menu and press T for transmit. Hit enter three times to get back to terminal mode and lines of hex Should start scrolling across the screen. When the scrolling stops, the transmission is Complete. You must now close the receiving buffer by sending a control "T", That"s it!! The person at the receiving end Should have the same number of Bytes as vou in the buffer. They can now simply exit to BASIC and there should be a program there, ready to run or save! Note that directly after the receive buffer is closed You can type to them to indicate that you are finished the upload and to check the results.

Sending and receiving machine code is by no means complex but it is a little trickier than BSGTIC gm iisten up. [he settings should be the same as sending a BASIC pragram however, you must expand the sending buffer to the same number of bytes that you are sending. The method for doing this is as follows.

First find the number of bytes wou are going to send and plug it into the formula below. This farmula will give you the pokes you need to expand the buffer. LB=A-256XINT(A/256) HBsINT(A/254)

where A is the number of bytes you wish to send + 26718.

Now that you have the correct pokes you must follow this procedure exactly. Load MTERM II and clear the Suffer, then exit to EASIC. Next make the fcliowing pokes-23527,LB and 22622,HH8. Call up MTERM II and axit to BASIC again. Mow da the pokes again. I don’t understand why these pokes have to be done twice but you do not get an

Pa. 1

accurate buffer expansion unless you do. Now at lang last

you can load in the machine code but you must load it in at location 25719. You can do tris b; using the following command: LCAD "filename" CODE 26°18. After the code has loaded you can call up MTERM II and connect with the receiving RPariy. jain, the receiving Darty must have the butter empty. The sending procedure is the same as BASIC. Now the person at the receiving end has to fool around a little. First they must write dawn the number of bytes in the buffer then exit to BASIC. Mext they must Save the bytes with this command: SAVE "filename" CODE 24/7ig, bytes in buffer. Now, the receiving person has to know the correct location for the coda to run at. The code is then loaded back in to the correct location with this command: LOAD "filsname" CODE flocation>. Then the code can be resaved now from it's carrect location. Whew! Wasn't that easy? You can send TASWORD files with the same method as sending Machine code but your CON Should be NONE and you may have to hit ENTER after every line goes by an the screen as it is being transmitted because TASWORD does nat embed a line feed or carriage return at the end of each line. I will be covering TASWORD file transmisson in a later column. There is an alternative to all this fooling around to send machine code and TASWORD files. There is now a fantastic utility for MTERM II available called LOADER IV by Kurt Casby. This utility not only makes sending M/C and TASWORD files a snap, it also provides an extra 28 auto-dial numbers and auto redial when busy! I highly recommend it. The best part of ali is the price. Just $7.75 U. s. Send to:kKurt Casby

25 Battle Creek Court,

St. Paul, MN. SSL1i? Well that’s all for this time!

TAPE AMPLIFIER FOR LOADING WEAK TAPES

Tapes which are recorded at a very low level are difficult + This little amplifier wil any tape output areater ;iaif a volt and convert i Square wave of about Av a peak. This fits nicaly he 2868's preferred range It also works with

x permitting a great tude in volume control ings for a successful load. e tape head alignment seems to be more critical than with hovever.

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The circuit is extremely simpla, using a 741 op amp as a standard inverting amplifier with a gain of 18 operating from a Singis power supply. I mounted mine on a small piece of perfboard and enclosed it and the battery in a

1"*2'»4" project box. I used a jack for the input and a short length of shielded wire with a male phone plug for the output. The entire circuit draws lees than óma with no signal so the battery should last a fair length of time. The battery

could be replaced with a 9v plug

Back if you had a spare wall outlet.

ZX-SHlers who need a non- inverted cutput for FASTLOAD

could simply use a 1458 dual 741 and add a second inverting stage.

LD Crawford London T/S Club

IOK

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LARKEN DISK CONTROLLER FOR THE TS2068 A REVIEW

by GF. Chambers

The LARKEN disk controller is a relative newcomer to the Timex/Sinclair scene, However four of our club members now have the LARKEN system up and running, and it is appropriate that

its performence be reviewed,

The specifications for the Controller are as follows: = 160K bytes per Disk ~ 125K bits per second loading speed. - Uses a SHUGART SA455 Drive or compatable - Provides single density, double sided operation. - Handles 3 data types: i.e. BASIC programs, arrays, and machine code, = Disk contro] possible from immediate mode, from within a program, or from M/C routine. - Disks are formatted for 80 1960-byte tracks. - System holds a maximum of 54 files per disk. - Provides commands DIRECTORY, FORMAT ,LOAD, SAVE DELETE, EXIT on the EPROM DOS - Provides above commands pius MOVE,COPY, and BADBLOCK in the Disk version of DOS. ~ Six error messages are provided, - Handles both 132068 and Spec/ROM modes, - Relocatable DO0S'es, including a SCREEN DOS. ~ Controller requires 5VDC/400ma. - Drive reqires 5VDC/400ma. and 12V0C/800ma,

The controller is supplied as an unhoused board, and includes a short connectorized cable that plugs into the rear connector of the 2068. The other end of the board has a male connector, and the unit fs supplied with a short connectorized cable to connect it to the disk drive. In addition, a connector with 4 short wires was provided as means of supplying power to the drive, The power supply is not provided, though a Schematic is supplied to permit you to construct

your own.

LARKEN ELECTRONICS R.R. #2 NAVAN, ONT, z CANADA K4B 1H9

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A 10 page (8 1/2" X 11") instruction manual is supplied, This provides both the installation instructions as well as the operating

instructions. The manual, such as it is, is a bit sketchy and will require careful reading to glean the necessary information requireD to get the system up and running. Some improvements are required here, i

The LARKEN controller is supplied uncased. Lying flat on a table in that state is both unsightly and an invitation to accidental electrical shorts, etc. The sketch provided in the manual shows dt lying parallel to the 2068, projecting out on the right rear corner of the 2068, I found this to be an entirely unsatisfactory approach, Instead I installed it in a second drive housing, running it straight out at the rear of the computer. The drive rests on top of the housed controller board, with the TV set on a platform above it. This makes for a neat compact installation. The 2040 printer plugs into an edge connector on the controller board, resting in just about its normal position. The only difference is that the Printer connector is turned to face rearwards and plugs into the controller board.

The board is provided with no means of mounting. There are no holes for standoffs, and the traces are too close to the edge for convenient rall mounting. I did mount mine in a set of rails; however it was necessary to move one of the soldered connecting wires to provide enough clearance.

The system is supplied with a 2K EPROM which holds the resident DOS. Via bank switching this DOS occupies the top 2K of memory, and reserves a further 2K of memory for data manipulation. Three other DOS! are supplied on disk. If the DOS in upper memory overlays data that you wish to SAVE or LOAD, then you call in one of the other three DOS. These DOS's are designed to be located at the 28K, 48K,and in the display file areas of memory. You choose the particular DOS to be used in tne SAVE/LOAD operation so that it does not conflict with the program/ data being SAVEd,

How does it work out in actual practice. Very well in fact. I have successfully SAVEd to disk a Spectrum program called SCRABBLE, that has a short BASIC program plus 40951 bytes of code starting at address 24380. | also have successfully placed TASWORD II on disk, which as some of you may know is spread out all over memory. As well, I have SAVEd one disk of games, with a front end menu to call up any game with a single key operation.

This may sound simple, but in practice it takes a bit of careful manipulation, What this

means is that once you have your drive,your problem aren't over, you still have some work

ahead to get your programs onto disk; its more than a matter of ur pressing a few keys. I wound up writing several software routines (in BASIC) to make the system relatively user-friendly. Not that

this is a problem unique to the LARKEN system. I'm sure al] systems need the same sort of massaging.

Py 9

The system has a COPY facility. On a single drive system, this means that it can copy one program (or block of data) at a time, and requires Swapping disks during the process. There is a constraint that a program to be copied be not longer than sixteen 1960-byte blocks.

There is a MOVE capability. This allows you to LOAD data into a differest location than it was SAVEd from, a useful capability. `

There is no MERGE function, Initially I thought this to be a minor shortcoming, however | now see that it would be useful in placing utilities in programs on occasion, The designer, KENNY Larken, says that it could be provided, if there was sufficient interest.

What do I think of the system? Just great. I would wholeheartedly recommend this system for the type person who feels capable of providing a Power supply; to housing the unit; and to writing or otherwise obtaining userefriendly (BASIC) operating routines, For those who want a ready-to-use system, better look elsewhere. However, may I make a caution, For the 2068 you