HR Invaders

ZX Computing

Nick Pearce

THE BEST THREE OF '83 Nick Pearce and James Walsh take a fond look back at the three best software packages they've seen during 1983. THE ZX81 OVERVIEW With 1983 fast drawing to a close, this is the time of year when it is traditional to look back over the past twelve months and take stock. I have seen a considerable number of cassettes during 1983, Some have been pretty mundane, many were very good and a few were outstanding, either in terms of their originality or because they broke new ground in the software market. It must be said that many of the major advances in ZX81 software were made in 1982 - I'm afraid 1983 is unlikely to be remembered as a vintage year for software. But, then again this is hardly surprising as the ZX Spectrum and a host of other cheap computers have been primary attractions, and the ZX81, introduced nearly three years ago and still extremely popular, is beginning to feel its age in computing terms. SPOILT FOR CHOICE I have chosen my three best packages using the following criteria: longevity, a program which survives constant use and remains as interesting as it first did; technical innovation, as to how well the programmer has used the capabilities of ZX BASIC and the limitations of the ZX81's memory; and originality. The kind of program that any ZX81 user would be happy to find in their Christmas stocking. I have not interpreted my brief too literally, in that some of the chosen three were in fact produced late in 1982 although their impact on the software market was only felt in 1983. Also, I have been unable to resist mentioning more than the stipulated three (perhaps I will be permitted to look back at four packages in '84 and five in '85!). Equally, for fear lest this short summary become a little more than a catalogue of ZX81 software, I have not made too many references to many other great cassettes which I'm sure you will have come across this year. My selection is very much a personal one, and for the benefit of users of both the unexpanded and the expanded ZX81, I have chosen a cassette of 1K games, a 16K game and for the more experienced programmer, Artic's FORTH implementation. THE NAME OF THE GAME Taking the game for the 16K ZX81 first, Odyssey's 'Invaders' package continues to provide enjoyment and I also use this game to demonstrate to sceptics that high resolution games really are feasible on the ZX81. As well as the impressive display, the action is fast and responsive, and as a game is great fun. Only Artic's 'Namtir Raiders' comes to mind as being as exciting to play, but this version does not have the same Hi-res display. Some users of Odyssey's game seem to have had some problems with the Hi-res display - it appears that access to the horizontal hold on the TV is sometimes necessary to correct the distortion. Persevere - you'll find it's worth it! You could also check out some of Odyssey's other Hi-res games, which I have heard rumoured are equally good. Someone with just 1K of RAM might appreciate a cassette such as Selec's 'Maze Guzzler' in their Christmas stocking. (They might prefer a RAM pack, but Selec's offering comes a lot cheaper.) 'Maze Guzzler' is a game after the 'Pacman' style, and all the usual facilities found on the 16K games available. The restricted memory has dictated a small screen display, but it is nevertheless a very good game. On the B-side of Selec's cassette is a game called 'Super-breakout'. This is a good 1K version, again with a less than full-size screen display. All Selec's 1K games cassettes are of a very high standard, although they have perhaps arrived a little late on the software market to achieve much penetration... which is a shame. Another excellent version of Breakout is New Generation Software's Gamestape 6 (formerly JK Greye's Gamestape 6). This uses a full screen display and is a first class game, and good value for money too! However, since it was produced well before 1983, it doesn't really qualify for too much of a mention here. GO FORTH So much for games. For the ZX81 programmer who feels like a change from BASIC, how about taking a closer look at Artic's FORTH package. Originally selling for around £30, this implementation now sells for £14.95 and should keep you more than busy over the Christmas holiday. The manual which comes with the cassette is not really intended for the complete novice, so if you're new to FORTH you will probably need a book on the subject to help you through the teething stages. I did not find this FORTH package particularly easy to use - not, I hasten to add, a fault of Artic's - because of the slow ZX81 cassette system. The FORTH compiler takes about six minutes to load, and the four screen editors take a further 20 or so seconds each. Apart from the initial wait to get the FORTH loaded, if you should crash the system half-way through a programming session, you will have a frustrating wait while you reload the compiler/editor and start all over again. Various versions of FORTH have been developed, but this version is an implementation of Fig FORTH. Artic supply a 'peel-off' keyboard overlay which is intended to be stuck on the ZX81 keyboard. The keys are similar to those normally found on the keyboard with a few exceptions such as the FORTH words and '!' on the 'W' and 'Q' keys. It doesn't have to be used - I didn't use it as I have a File-Sixty keyboard with moving keys - but it does help you get used to the package. FORTH is considerably faster to run than BASIC, and its power lies in the ability to allow you to define your own words (or functions). FORTH already has an extensive range of words and the programmer can use these to create additional words to do whatever is required. Once a new word has been defined, it becomes part of FORTH's vocabulary. The compiler takes up something like 9K of RAM, and what with the screen editors this only leaves about 2K left for the user to work within. However, as I mentioned before FORTH is a very economical language and you can achieve a lot within this confine. ZX FORTH is a first class implementation of this language and provides a good insight into its peculiarities. If it bites you, it should be easy to progress onto a dedicated FORTH machine or another FORTH system as Artic have kept very closely to the standard language. XMAS ADVENTURES Apart from the software mentioned here, I've got plenty to keep me out of mischief over Christmas. I have still yet to complete all of Artic's adventures - Espionage Island alone should keep me from overdoing the food and drink - and I shall need a clear head to brush up on my flying using Psion's 'Flight Simulation'. On a last not, happy Christmas to all ZX Computing readers, and good computing! Nick Pearce.

Sinclair User

GENUINE HI-RES IN SPACE INVASION Odyssey Computing has achieved the remarkable feat of producing, with no extra hardware, a genuine high-resolution version of Space Invaders for the 16K ZX-81. Invaders offers superior graphics and allows one or two people to play and provides a choice of missile-firing and bomb-dropping rates. The result is an absorbing game which should satisfy trigger-happy space fighters. Invaders is from Odyssey Computing, [redacted]. It costs £4.95.

ZX Computing

Nick Pearce

THE '81 SOFT SELECTION Nick Pearce casts his eyes over the latest software packages for the ZX81. INVADERS - ODYSSEY COMPUTING Invaders from Odyssey Computing is a high resolution yes, high resolution on your ZX81 - version of the popular arcade game. Unbelievable? Well, its true, and no expensive hardware either, just the standard computer with 16K RAM. None of the usual ZX81 characters to represent the alien fleet, in this game they are the genuine article. Action is fast and smooth too, and the explosion when your ship is hit really is shattering! After LOADing - which takes about five minutes - the program runs automatically. As well as the Hi-res display the facilities offered are impressive. The game required is first set up: a one or two player game can be selected (two players can either take turns or play simultaneously); the keyboard mode is selected; and the missile firing rate and bomb dropping rate are chosen. Selecting a high missile firing rate and a low bomb dropping rate gives a relatively easy game in which even the beginner can achieve a high score; increasing the bomb rate and or reducing the missile firing rate makes the game more difficult for the experienced player. The game is robust but will crash if, for example, invalid entries are made in the setting up sequence. A small price to pay for an excellent game. I am afraid your existing library of arcade games for the ZX81 is likely to lose much of this one. No sound or colour, of course, but the Hi-res display really does break new ground. An outstanding achievement. The use of high resolution graphics will almost certainly open up a whole new generation of ZX81 software as other software houses follow suit. An excellent game. Invaders costs £4.95 from Odyssey Computing, [redacted].