THE JOYSWITCH The joyswitch is a device to switch between the mouse and the second joystick. You may have seen a device for this purpose advertised in the overseas magazines. However the Joyswitch has an improvement over the commercial device. The bought one has a switch on the little box, which is used, as you probably guessed, to switch between the two devices. (e.g. Joystick 2 and the Mouse. As the AMIGA, the mouse, and the Joystick already contain many switches, I could not see the point of adding more. Keyboard control is out, as that would involve software, which would not be compatible with protected games. The obvious answer is to somehow use the switches already provided in the joystick and mouse to operate the switch. This can be done, by using a logic gate to detect the state of any desired line from the mouse or joystick to toggle the switches. The advantage of this is that you don't need access to the switch. The box can be out of the way under your desk or behind your machine. In the circuit provided in the accompanying IFF file, the state of the fire button on a joystick, and the state of mouse button 1 and 3 are used to toggle the flip-flop formed from the quad nand gate. A schmitt triggering nand gate is used to make sure it responds definitely to the possibly cruddy state of the contacts in a cheap joystick. The Q output of the flip-flop enables the switches from one device, and the inverted connection enables the switches from the other. Further presses of the button make no difference to the state of the flip-flop. Two questions may have occurred to you by now. Why mouse button 3? What happens if someone presses the button on the mouse while I am playing Gauntlet/Garrison/Marble Madness? Well, if you check page A-7 in the Introduction to the AMIGA 500 or the equivalent for other models, you will see that the port on the machine supports three mouse buttons. The two which are actually used are 1 (left mouse button) and 3 (right). Presumably input from button 2 is directed to NIL: For the second question, as you may suspect, the other device will take over control, giving unpredictable results, until you recover control by pressing the fire button. No physical harm can occur, except to the culprit, it's just that your AMIGA will try to treat mouse data as joystick data ( or vice versa if the opposite occurs when you are using the mouse). The solution is to keep the unused device out of reach of toddlers. The version described here is called 1.1, because of another feature I forgot to allow for in Version 1. When playing Marble Madness, if you want to adjust features such as number of players, difficulty level and control device type, you need to go back to the mouse. Unfortunately, the pointer will be sitting on the GO device on the screen, and because the pulse from the mouse is passed through as well as operating the switch, the game will promptly restart. The solution to this was to arrange for either mouse button to control the Joyswitch, so if your pointer is sitting on a gadget you don't want activated, you push the right mouse button instead of the left. If this feature was not provided you would be stuck- you can't move the mouse until the joyswitch is switched, and you can't switch the joyswitch without activating the gadget. The current version is now 1.2 because while examining an audio digitiser with ideas of reverse engineering it I realised that the Joyswitch could copy their idea of mounting a socket on the edge of a double sided printed circuit board. The board has been redesigned to do this, and also uses 1 less integrated circuit as I decided that it was actually unnecessary to switch the fire/mouse1 and mouse 3 lines. There is an option here. You can install 8 diodes, 2 of which must be gold bonded low forward voltage drop types for mouse 3 or you can install 5 diodes and 1 link. In the first case, you can plug the mouse in either port. In the second, you must plug the mouse in the port which is wired for it. The main advantage of the first approach is that you will probably find that on power up, the joyswitch habitually selects one port. For convenience, it is nice if this is the mouse. If you have configured the device so the mouse can be in either port, you can just swap it over. If it has to go in one port, you are stuck with whatever comes up first and will have to push the button to change it. This is of course no great hardship. Actually, if you want to bias it so it starts one way, adding a small capacitor from pin 6 of the port you want selected to ground would do it. Probably about 100pf would do the trick. As the Joyswitch is designed specifically to switch between the mouse and the 2nd joystick, it is not necessarily suitable for switching other devices. If you have something exotic, such as a light pen or a joystick port digitiser, I suggest you tread warily. Feel free to consult me as I could suggest some ways of switching other devices. However, most of these devices are not used as often - it's not such a hardship to plug in a digitiser before a session, and unplug it after. As dongles are probably not smart enough to press the fire button when they want to be switched on, it is probably of little use to plug one of these into the joyswitch. Adding a button to the joyswitch would defeat the original purpose of the device, which you may remember, was to not add switches. Some of you may be wondering about the power drain of this device. Well, the maximum power drain occurs when the select buttons on both devices are pushed at once, and is 1 ma. Incidentally, while both buttons are pushed the switch will only select one device. When neither button is pushed, the current drain is less than 1 microamp. ( I measured it with a DVM which only has a resolution of 1 microamp). I have since checked with an analog meter which reads 12 microamps full scale. No noticeable deflection occurs, so the current must be well under 0.1 microamp. Anyway A500 owners need not fear the consequences of using it. This is one reason that I wanted to avoid using a mechanical relay- that would increase the consumption by at least 100 ma. The components are all generally available from local suppliers, although Dick Smith has been out of 9 pin D sockets for 6 months out my way. I got mine from Computer Cabling in Wellington. I suggest using ribbon cable with an Insulation Displacement connector for the connection to the computer, although the design of the board does permit mounting the plug direct on the board. If you do this, make sure the joyswitch box is supported by the table or whatever your Amiga sits on. Don't leave the weight of the Joyswitch hanging on the port as it is bad for it, and one day it will get bumped and break something, probably the main board of your Amiga. Also don't be like me and leave the naked printed circuit board sitting working in a drawer under the computer for months. Sooner or later someone will drop something conductive on it and short it all out. (It hasn't happened yet!!) Try the Joyswitch out on a separate power supply using a meter to monitor the current before plugging it into your Amiga. Even a six volt battery will do for a tryout. (The CMOS integrated circuits will run happily on anything from about 3 to 15 volts, but if you are going plug in your mouse try and arrange to have 5 volts.) If the current drain is not excessive, i.e. it is comparable to the figures above, you can safely plug it into the Amiga and try it out. As long as you have checked that the circuit does not draw too much current, faults are not likely to hurt the AMIGA. Do check your circuit board carefully, or better, get someone else to, especially if you are not an experienced constructor. Watch especially for solder bridges between pins which are not supposed to be joined. If you make mistakes with hardware, you can do real damage. For instance, if you short the Amiga's power supply, you could burn out the tracks on the printed circuit board. This is why I emphasize measuring the current on a separate supply before connecting to Amiga. If sufficient people enquire, I will arrange to have the double sided circuit board made commercially. It would cost somewhere about $25.00. The 2 D sockets mount on the board so the only wiring is the ribbon cable to the plug, unless you decide to edge mount that as well. The board will not have plated through holes unless I get an order for several hundred!!! Also, again if sufficient people enquire, I could put together all the parts required as a kit. The electronics is under $10, but the connectors and the jiffy box to put it in are much more expensive. This is of course one of the fundamental facts of electronics - the high tech stuff is cheap, it's the low tech stuff that really costs money. It would probably be about $50 to $60. Of course it will probably save you this much by not wearing out the connectors on the computer. See below for a breakdown of costs. CopyRight Notice: As designer I retain the copyright for this published circuit and printed circuit board design. Individuals may construct this circuit for themselves or their friends on a not for profit basis. The designer accepts no responsibility for any damages resulting from the construction and use of this circuit. Anyone wishing to construct this circuit on a commercial basis should address their enquiries to: J. H. Olsen 1 Raroa Tce, Tawa. Phone Wellington 324-679 Summary: Advantages ** No more unplugging joysticks. ** The joyswitch need not be accessible (no controls). ** Very easy to use- just press fire or select on the device you want to use. ** Low power consumption. ** Compatible with all known versions of the operating system and with all combinations of memory, disk drives, processors, and coprocessors. (Provided there is still room on your desk for the little box!) ** Not able to be harmed by Virii, Bacteria, or Fungii!! Disadvantages ** Can be switched by others when you don't want it. (But you can easily switch back by hitting fire. If you are playing a shooting game you may not even notice.) ** Not suitable for switching Dongles or Digitisers. ** Not available in Amiga beige. (Unless you find a box that colour.) Incidently, if when you boot up the initial Dos window outline is flashing, it will be because you have left the 2nd Joystick switched to Autofire. This is a convenient reminder to switch it off so you can use the mouse! PARTS LIST Prices from 89/90 New Zealand Dick Smith catalog. Parts can be obtained cheaper, but Dicky has plenty of outlets and these prices provide a good guide as to what is reasonable. Catalog Numbers are shown. Foreign readers (i.e. Australians) should note that prices are likely to be very different due to exchange rates in their catalogs. Description Number Quantity Price Each Jiffy Box H-2853 1 $5.95 $5.95 D Socket 9 pin P-2685 1 $4.95 $4.95 D Plug 9 pin P-2684 2 $4.95 $9.90 CD 4093 Z-5693 1 $1.50 $1.50 CD 4066 Z-5666 2 $1.95 $3.90 10 K resistor R-1098 2 $0.10 $0.20 .1 Microfarad Greencap R-2100 1 $0.22 $0.22 Diodes either OA47 Z-3232 2 $1.75 $3.50 plus 1N914a Z-3120 6 $0.20 $1.20 or 1N914a Z-3120 5 $0.20 $1.60 Which comes to $28.22 for the choice with the cheaper diodes. As noted above, this only means that you will have to plug your mouse into the correct socket for the mouse three button to work, and it may wake up when turned on with the joystick selected, which will suit game players but will mean mouse users have to push a button to activate the mouse. This is no inconvenience, so I suggest going the cheap way. I have tried both and find the whole thing works very well either way. I have not included a price for the printed circuit board as this would depend on the scale of production. If hundreds of local people ring me up wanting one I will assume that demand will be vast and arrange quantity production which would be cheaper. If no one rings up I will assume no one likes the Joyswitch, or that you all built it on VeroBoard. (which is perfectly O.K. for those who want to do it that way) If enough people want a kit, I will arrange that, and because I would be able to make quantity purchases the overall price would probably be less than the prices above. This is not a commercial venture !! but there would neccessarily be a profit margin on the kits, partly because I would probably pay students to pack the components, and partly so I could pass a few dollars on to the User Group. Future Projects Under Development and/or Consideration Stereo Digitiser. I have done some preliminary work on the design of a digitiser which would be capable of stereo samples to about 10KHz or mono to about 20kHz, using two cheap readily obtainable A/D convertors. It would be compatible with the Audiomaster software, which is commercially available without a digitiser, and if possible with public domain software as well. A500 expansion. It should be possible to build a device to allow the use of A2000 cards on an A500. In fact it has been done commercially, but I have some ideas of my own. The commercial one only accomodates 2 cards, and I would like to provide for more. My thinking at present is along the lines of :- Take one IBM Pc or Clone thereof (EECCCHHHHH!!!) While struggling to overcome nausea, remove everything except the power supply. (All we want is the case and power supply, and hard drive if one is available.) Build a new "motherboard" which has a connector on a short lead which plugs into the side of the A500 Plug in some A2000 cards, such as the hard drive controller, and the memory card (if you are rich!!). The one I want to use is the A2090A hard drive controller as this will support readily available ST506 hard drives drives such as are used in IBM Pc's and clones, as well as the better, more expensive and rarer SCSI drives. There is a lot of work needed on this idea yet, so don't hold your breath, but if someone offers you an unwanted IBM Pc or clone (and aren't they ALL unwanted!), especially with a hard drive, then grab it provided of course you don't have to pay too much. Any hardcore hardware techies in the Wellington area who would like to work on this with me are welcome to ring. Incidently the zorro interface on the A1000 is very similar to the port on the A500, (which is very similar to the CPU slot on the A/B2000), so A1000 owners who wish to use A2000 cards could be interested too. Actually the A500 slot effectively IS an A/B2000 Cpu slot except that the 28MHz clock is not connected, and it is male instead of female, so it should be possible to connect up an A2620 coprocessor to your A500 if you really need the speed. (and have the money)