UNIVERSAL JOYSTICK PRODUCED BY AGF

AGF has produced a programmable version of its joystick board which works on either the ZX-81 or the Spectrum. There are two joystick sockets for standard Atari-type joysticks but they both operate the same keys. There is no longer a need for a specially-modified joystick. The programming is done for each of the five positions of <, >, :, /, and FIRE button by two crocodile clips for each of the positions.

One clip selects one of five 'D' bars and the other one of the 'A' bars. Thus any of the keys on the 40-key keyboard can be simulated by various combinations of the two clips.

A chart is given on the back of the joystick giving the 'D' and 'A' numbers for the various keys.

It would have been far easier to use if it had been set out like the keyboard in a 10 by 4 line matrix instead of an 8 by 5 matrix. It would also have been useful to see that or a picture of the keyboard showing the relative 'A' and 'D' lines in the instructions.

Ten programming cards allow the user to mark the position of the clips for various games, so reference to the instructions is not required every time. Extra packs of 10 can be purchased for £1.

The board has an extension piece on the back for any other add-ons and is easy to use.

One difficulty might occur for people who have fined a ZX-81 or Spectrum into a case; the crocodile clips may not fit between the case and the board which is tight against the back of the computer. The board should be very popular with games users as it means that any software can be converted to use joysticks without special tapes or joystick-adapted programs. It cannot be out-dated as all games have to be designed to use the keyboard.

The joystick board costs £33.95 and includes a demonstration tape. Joysticks cost £7.54 from AGF Hardware, Freepost, Bognor Regis, West Sussex PO22 9BR.

AIMING TO SPEED THE RESPONSE

Stephen Adams looks at the wide range of joysticks that are now the market.

Joysticks are a favourite weapon against space invaders, pirates and in other fighting games. They are also very useful for flight simulation, maze games like Mazog for the ZX-81 or Escape for the Spectrum. That is because they speed the response to the games by up to 300 percent and if the games have been written to obey joysticks, the response to the keyboard has probably made the game run more slowly.

Most work on one of two principles, the commonest being the switched type like the Atari joystick. The other is the proportional joystick, which instead of just indicating the direction of the joystick also sends back a report on its exact position. It does so by giving an X/Y value for the position of the stick in the vertical and horizontal directions. You can write software for those joysticks but no commercial software uses them.

The Atari joystick set a standard by being the first to be used on a video game and since then the style has changed but the connections to the game have not. The Atari joystick has a 9-pin "D" type socket on the end of it which has five pins at the top and four pins at the bottom. They are numbered from one to nine, starting at the top right-hand side - looking at the plug - and only pins 1-4, 6 and 8 are connected. Those pins are connected to five switches in the joystick, one side of the switch being connected to a numbered socket, and the other being connected to a common point, which is connected to pin on the socket.

Operating the joystick in any of the four directions makes that switch operate, connecting the common pin to the socket pin of that switch. The fifth switch is the fire button. Thus only one switch can be operated at a time, plus the fire button. That kind of switch cannot be used directly in place of the keyboard switches, as all the switches are connected together. Therefore an interface has to be used to connect the joystick to the Spectrum without damaging it.

The interfaces are of various kinds but a standard seems to have been set by Kempston, which contacted software companies before it launched its joystick to pursuade them that there should be a standard way of using a joystick on a Spectrum.

That standard way of working has now been written into some of the software by mos of the big companies as an alternative to using the Sinclair keyboard.

The software is easier to write if you have only one address to look at or to control. It is also not difficult in machine code to take one byte from an address and check that a switch has operated. It is much easier than scanning the entire keyboard for several different keys.

The address the Kempstori uses is very simple; it requires only bit A6 to be low using anIN instruction to operate the chip. Address 31 is used to read the value of the joystick. The joystick switches each operate one bit of the binary data returned from the port and as the Kempston Competition Pro joystick allows you to operate two switches directly instead of one - allowing you to go in diagonal directions as well - it is very useful. Only five of the bits are thus used and all the rest are set to 0. If one of the joystick switches is operated, that bit changes to a binary 1 and the number returned will be greater than zero.

The AGF Interface II allows you to simulate a set of keys on the keyboard but they are fixed to the cursor keys and use 0 for the fire button. It also allows you to use other devices on the back of the joystick and is available in ZX-81 and Spectrum versions.

Unlike the Kempston joystick, which works on both the ZX-81 and Spectrum with the appropriate software, keyboard interfaces for the Spectrum cannot be transferred to the ZX-81 as not only is the edge connector too big - 28 ways instead of the 23 of the ZX-81 - but the expansion port has different connections.

The Protek is also a cursor-type interface but like most of the interfaces reviewed has no PCB edge to which to connect anything else like a sound board.

The Jiles Electronics interface is a three-way, bare-board device which can he made to look like that from Kempston, a cursor-controlled joystick, or to work Psion programs. The selection is via two little pegs and is probably the cheapest solution to fitting joysticks, at £13.95.

The Sinclair joystick port in Interface Two operates either the first five or the last five of the number keys. The only software which works with the system is that from Sinclair or Psion.

Soundboards like the Fuller Box and the ZXM from Timedata also have joystick interfaces but use different addresses for them.

Programmable joystick interfaces have also begun to appear for the Spectrum which allow you to program the positions of the joystick to operate different keys on the keyboard. That allows you to operate it with any software, whether it be designed for the joystick or not.

The simplest to understand is the Pickard controller, a plastic box on which there are 40 sockets, one for each key on the keyboard. Five jack plugs, the same type as the cassette leads, are used to program the five positions of the joystick by plugging them into the appropriate sockets for the game.

At no time is the keyboard disabled. The connection to the joystick is via an Atari socket on the side and the connection to the computer is made by plugging-in plugs to the keyboard sockets inside the case. The power is obtained by plugging the power supply into the unit and then a flying lead is plugged into the computer power socket. It is a very simple and inexpensive way of doing the job and will work for the ZX81 or Spectrum.

The AGF version also programs it manually by using a set of crocodile clips, one for each data line and one for each address line. It now seems a complicated way of doing things, as it is not as easy to understand as the Pickard, but it does not involve entering the computer. A set of cards is provided to mark the positions of the clips for each game, which seems to prove the point. The unit also tends to be unstable and programming it during a game can crash the system.

Cambridge Computing and Stone- chip have employed a different method to program the joystick. They have used 1K of RAM to store the positions of the keys where the joystick should operate. In the Stonechip design you can even have the diagonals operating different keys, giving nine positions.

The Stonechip is also the easiest to operate and has the advantage over the Cambridge in that it will also operate the Microdrive interface, Interface One. To use it all you have to do is push a three-position switch to PROGRAM on the front of the unit and, while holding down the key for that position, operate the joystick. A quick flick is all that is required for each position of the joystick. Then move the switch to NORMAL and LOAD the game.

To use the joystick just switch it to PLAY and the game will respond to the joystick. The review model also disabled the keyboard when in use but the company says a small modification will be done to all the current units to prevent that and will be informing all customers so far as to when to return units for free modification.

The Cambridge unit requires you to LOAD a tape first, which takes you through a menu to program the joystick. If you touch the joystick while LOADing the program, it crashes. It also appears to crash after programming the joystick completely as it NEWs itself to be ready for the next program and that is not mentioned in the instructions - but the joystick still works.

The joystick settings can also be viewed and recorded on tape. The menu program still has to be LOADed first. It has also a rear edge connector so that other things can be plugged-in. The interface is intended to work with the joystick which accompanies it but can still be purchased separately if you want to use an Atari joystick.

The advantage of using your own is that you not only have an eight-position joystick but two independent fire buttons for games at a cheaper price than Atari. Cambridge says it will change software when it can obtain a Microdrive on which to test it.

Electrotech also uses the same system to program its joystick but its interface board is uncased and will work only with its joystick console. The console contains a four-position joystick and three large 1in. fire buttons and looks as if it should belong in an arcade game. It is very robust but costs at least half as much again as the other two.

Joysticks tend to be personal things, so I asked a few friends at a computer club and my children for their options on the range available. The result is clearly for the Kraft joystick, with Cambridge Computing second with its two fire buttons. The Kempston Competition Pro joystick is a good all-rounder with its eight positions.

The others go to show that an increase in price does not always provide easier control. The Jiles Electronic joystick is probably the least helpful, as its stick becomes more like a flexible toy in use. The Atari shows how much joysticks have developed, as it now seems very stiff and unresponsive compared to the newer types.

INTERFACITS - JOYSTICK INTERFACING INVESTIGATED

A comprehensive round up of the units available - checked out by our team of reviewers.

One of the first add-ons that a computer owner may contemplate buying is a joystick of some kind. The increase in control that this provides is of obvious benefit to the dedicated games player. In addition it is becoming increasingly necessary for some of the complex graphics packages that are appearing for the Spectrum. However if you have not yet taken the plunge and are now contemplating the purchase of some form of controller you have a difficult choice ahead of you. In essence, most of the actual joysticks are very similar, and your eventual purchase will be based upon personal preferences for shape, size, ease of use etc., but the biggest decision to make will be that concerning the vital link between your joystick and the computer i.e. the INTERFACE.

Interfaces allow the use of joysticks with compatible software, and although there is a great variety of material available for use with all the more common interfaces no single one will give you control over every game, unless, of course you opt for a PROGRAMMABLE INTERFACE. These claim to give you joystick compatibility with ALL software.

AGF sell a version of this interface for both the Spectrum and the ZX81 and both cost £26.95.

The interface works by duplicating the keyboard layout with a grid of wires. The wires ending in crocodile clips can be attached to the various grid wires to route specific keys to the joystick. This means that all games can be controlled by joystick although you must use the keyboard option and not the joystick one when provided.

The joystick is connected by a standard 9 pin 0 socket so it is compatible with the majority of the sticks on the market, two sockets are provided for two sticks for two players to play alternatively. Both sockets operate on the same keys and both sockets and the keyboard are always operative. A possible cause for dispute when used by two players! A set of quick reference cards, a demo tape and a stick on chart completes the package.

The sight of uncased wires and chips may put off some users, but treated reasonably, this is an almost foolproof method of providing joystick control to any game.

The unit has a through port and further peripherals can be added afterwards, I used a Centronics interface and a speech unit with it and had no problems.

STICKING WITH ADJUSTABLES

There are now several different ways of hanging a joystick on to the Spectrum, and they fall into two distinct categories - the dedicated type, which uses fixed input/output locations, and the more recent programmable type, which can simulate any chosen keys when the joystick is moved. Andrew Pennell, is concerned with the second variety - devices which should, in theory, offer compatibility with all software. He examines products from AGF Hardware, Cambridge Computing, Downsway and Stonechip.

All four of the interfaces looked at allow one joystick (or two in the case of AGF) to be connected to the Spectrum, via the industry standard 9-pin, D-type connector. Any joystick used must be the switched type, and not the proportional variety as used on the BBC Micro, for example. These consist of one switch for each of the four directions, and one for the fire button. Diagonal movement is recognised by two direction switches being activated simultaneously.

AGF HARDWARE SOLUTION

AGF was the first company to produce a programmable joystick, and this device remains the only true hardware-programmable interface. It consists of a large, exposed PCB with four ICs and 13 vertical bars. The back of the PCB is covered with black plastic, and for that reason it looks much neater from behind! To program it, two crocodile clips for each direction must be connected to the appropriate bars. A self-adhesive conversion table is supplied to convert each key into the two required connections. A total of ten crocodile clips must be attached, and probably it's best to do this with the power removed. Ten 'programming cards' are included on to which can be recorded the plugging arrangements for your most popular games.

When first connected, the interface firmly refused to respond to the fire button on the joystick, no matter how it was programmed. A dismantling of the stick showed nothing wrong, but closer inspection of the interface revealed a truly terrible joint to one of the clips. Swift action with the soldering iron soon had it working. One would hope that the interfaces are tested before dispatch to customers. This exercise brought to light another unredeeming feature of the unit - the edge connector that plugs into the Spectrum is incredibly tight, and almost impossible to remove (faced with the same problem, our editor had to resort to deft use of his letter opener). It's hard to imagine any of this palaver being good for the Spectrum's connector, although removal should not be necessary very often as a carry-through connector is provided to allow any further accessories to be plugged in, piggyback style.

AGF actually provides two joystick sockets, but these are connected to each other. The company says that this makes it easier to take part in two-player games, but some may think it's just as easy to pass on a single joystick to the co-player. The sockets are mounted on the top of the unit and therefore the joystick's plug and cable stick straight up in the air - thus easily obscuring one's view of the television screen.

However, once the operation had been figured out and the fault corrected, the interface worked very well. Programming is pretty simple and quick, and is of course retained once power is down. A simple demonstration cassette is included but, even so, at £33.95 it does seem a little on the expensive side.

CAMBRIDGE INCOMPATIBILITY

The next interface in line was the one from Cambridge Computing, and this comes supplied complete with joystick. It's controlled by software, but requires a program to be loaded from tape first. In fact the program allows a library of data for each game to be stored on the reverse side, so each key pattern has only to be entered once. This does mean though that the tape must be run before play can begin. During the first programming sequence a problem soon became apparent - the whole machine 'hung' with the word 'OK' on the screen. It wouldn't even Break, so all that was left was to pull the plug out. Only after running through this loop again did the truth strike - your reviewer is one of the few to possess both a ZX Interface 1 and a Microdrive, and the Cambridge port uses one of the Microdrive I/O locations. Cambridge really has no excuse for this blunder, the Microdrive ports having been documented since the day the Spectrum was launched - take a look at page 160 of the manual, guys!

Interface 1 was removed for the rest of the test and that obviously means that the Cambridge interface will not work with any games that load from Microdrive. Once programmed, however, the joystick interface worked well, with either a normal stick connected, or with Cambridge's own. The latter has a second and independent fire button, which can be programmed to simulate a different key to the first. However, the only game to come to mind that needs two fire buttons is Penetrator.

To test the device thoroughly it was used on one of the toughest games for any joystick - Jetpac by Ultimate (your reviewer's normal rig being the Kempston non-programmable interface plus Competition-Pro joystick). Opinions on joysticks are very personal things, and one man's loathing is another man's love. However (to digress a little from interfaces) after playing with the Cambridge stick for some time it seemed to me the device somehow failed to make the grade. It's noisy and not very sensitive and the two fire buttons are quite small (in fact it seemed best to program them both to the same key). The shape of the case looks as if it is designed to be held in one hand and operated with the other, but cramp set in after a while and the only resort seemed to be to rest it on a table instead.

The Cambridge interface does have a carry-through edge connector, but if it is incompatible with the Microdrive it is possibly incompatible with most other add-ons too. That aside, it works well, the only hangup being the tape that needs to be loaded before use. It comes reasonably priced at £24.00 for the interface only, or £29.90 if the joystick is bought as well.

DOWNSWAY - IN REAL TIME

The Downs way unit is programmed in a very different way to the previous two - namely in 'real time'. There is a 2-way switch on the back of the unit, which is normally in the 'up' position for program mode. To program it, the memory in the interface must first be cleared - which is achieved quite simply by moving the stick to all its positions in turn, and pressing fire each time. This done, each of the eight positions may be programmed by the holding down of the relevant keys and the moving of the joystick to the required positions, each time letting it return to the centre position. The instructions say that the diagonals should be programmed first, but it seemed to me that any order would do, provided the fire button is left until last. A total of nine positions are required, and the diagonals in particular can demand a lot of finger dexterity as you press two keys with one hand and hold the stick exactly diagonal with the other.

Once programmed and switched back into the play mode, you're ready to start. However, one great advantage with the device is that the interface can continue to be programmed after a game has been loaded, and therefore any mistakes can be corrected as you go along.

The Downsway interface is easy to use, quick to program and also the cheapest, at £22.95. My only quibble is that there should be an indicator label near the programming switch.

STONECHIP DEXTERITY

The final interface to come under scrutiny, by Stonechip, at first glance seems very similar to the Downsway one. It's programmed in the same way, the only apparent difference being that there is a 3-way switch - selecting normal, program or play modes. However, in use it proved to be rather different to the Downsway device. When in program mode, the Spectrum behaves strangely. It makes unusual buzzing sounds, and the border flashes. But the sequence of operations to program it remains the same, although with the one important difference - twice as many operations are required, as the joystick has to have all eight positions programmed once with the fire button pressed and again with it released. As well as taking some time, the task proved not an easy one. To program each diagonal with fire held down requires three keys to be pressed with one hand while the other holds the stick diagonal and presses the fire button. And now, with my teeth...

As with the Downsway unit it can be re-programmed after a game has been loaded, to correct any errors - a useful facility. Once all is ready the unit must be switched to the play mode for the joystick to be able simulate the keys. But this in itself presents problems for now you will notice that no keys on the keyboard work, and the ear socket is disabled. That means programs will not load and the switch has to be continually flicked back in order to re- enable the keyboard and thus allow the choosing of options from menus.

The Stonechip interface seems to offer similar facilities to the Downsway one, but with several disadvantages to weigh against it. It's also more expensive, at £24.95.

MODUS OPERANDI

How do they all work? Well, the Spectrum keyboard is based on an eight by five matrix, and was designed to be as simple as possible to read electronically. The AGF interface duplicates the matrix, but instead of having keys on it you can connect each directional switch at a particular point to simulate any key. This is electronically quite easy, but difficult to manufacture because of the matrix connections. The other interfaces are all basically similar to one another, showing just minor differences. They each contain 1K of RAM, not (as normal) in the memory map but in fact in the keyboard I/O space. This enables them to be programmed, ie. have the RAM written to, and then simulate the keys when they are read.

The actual method of switching between modes differs widely between the three. Cambridge uses another I/O port as a switch whereas the others just use a switch. The Stonechip design only has three ICs, excluding the RAM chips, but one can't help feeling that too many features have been cut to reduce the chip count.

TAKE YOUR PICK

In conclusion, it's worth the potential purchaser first deciding whether a cheaper, dedicated interface will suffice. There are three main types, produced by Kempston, Sinclair and AGF. If it will not, then choose the method you wish to use to program it - hardware, software or real-time. My personal view is that the Downsway unit takes the chequered flag, being cheapest and most easy to use.

However, the AGF interface may be worth the extra expense for those preferring something that's hardware programmed - even if, as in this case, the result is a little unsightly.

REC. PRICE: £33.95

PROGRAMMED BY: Hardware

COMMENTS: Over-tight connector, rather expensive, somewhat unsightly, works well.