The Hard(ware) Facts

by John J. Smith


Issue 11

Sep/Oct 84

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Ever thought about monitoring the sound produced by your computer on headphones? This is okay if you have a TV with a headphone socket but it is not really hi-fi because it is usually wired by the manufacturers into the speaker circuit and any hiss or hum present is more noticeable. So what can you do to improve quality or if you do not have a TV with a headphone socket? Firstly you can forget any ideas you might have of adding a socket to a TV which was not designed to have one. Definitely not on. You have a choice of simply connecting a small amplifier to the audio output of the computer externally and letting this drive your headphones as shown in Figure 4 or fit a small special purpose amplifier inside the computer with a socket for headphones fitted in a convenient position. The latter is of course the neatest solution but requires more work and involves drilling holes and soldering. The choice is yours.

To prevent any problems with possible leaky batteries it is suggested that batteries are not put inside the computer. Possibly a plug and socket arrangement at the rear or a separate low voltage power supply unit driven from the mains. Such a project is for experienced constructors only though.


One of the lesser known parts of the Atari is the peripheral connector at the side into which your 410 or other peripherals plug. It is a 13 pin Molex plug, part number MX 7514-4.13 - a non-standard plug if ever I saw one! A pity Atari did not put on a nice standard D-type connector.

Not only is the number of pins non-standard, the diameter and spacing is also different so any ideas you may have about cutting down a 15-way D-type socket simply will not work, I have tried it. If you want to plug anything in to this socket you have a problem. I have not yet been able to find a supplier in the U.K. for the socket to fit the 13-way I/O plugs but you can buy these sockets with any length of shielded (screened) cable attached from Elite Digital, P.O. Box 1414, Melville, New York 11747. For those of you who are interested in trying expansions through the I/O port details of the connections are given in Figure 1.


The advantage of games cartridges is that they instant load, however you still have to open the lid to change cartridges. With tape or disk it is possible to load a particular game by typing in its name and the computer will search the tape or disk for the program required. It would be nice to select cartridges in this way but of course you can only have one cartridge inserted at a time. Even on the 800 the second slot is of no use in this connection.

The solution is, I think, to have a separate box containing its own low voltage power unit and say 10 sockets wired in parallel, except for the CS pins which are individually wired. A multiway ribbon cable is then fitted with a suitable connector and plugs into the left hand ROM socket of the computer. It should be possible for someone to write a short program and with the aid of an EPROM burner put it on ROM which would be put in slot 1 of the expansion box. This ROM would contain a menu. The BASIC cartridge would be put into slot 2 with various other games or languages taking up the remaining slots. The Menu program would ask which of the available cartridges you wished to load and exiting a program by using SYSTEM RESET would bring you back to the Menu for a new selection. I thought of this idea about six months ago and keep meaning to try it out but available time does not permit. On this occasion perhaps I can pass the idea over to PAGE 6 readers and maybe one of you could come up with a finished product or prototype. Figures 2 and 3 give a little more information to get you started.