How many? There is no fixed rule about how many computers you need. Successful centers have started with as few as two and have grown gradually. One computer is probably not enough. The exact number of computers that you need is determined by three criteria: the size of your club, the amount of allotted spaces, and the number of children who will participate. (In general, two children work together at a computer terminal. If you make sure to allow for some non-computer activities, six computers should be enough for 15 children).
What kind? ANY kind of computer can be used in the 5th Dimension. We have used Texas Instruments, Kaypros, Apple IIc's, e's and gs', Macintosh and IBM compatibles. The main trick is to get computers for which there is at least SOME software that you can find a use for. Even Nintendo games can be used in a 5th Dimension but they require that you take special care with your task cards.
An added concern is that continued advancements in technology affect the availability and accessibility for possible repairs that might be needed for older computers.
All forms of personal computers can be used in the 5th Dimension. At present there is a good deal of software available for the Apple II series, but this computer is being phased out. IBM PC's and compatibles are useful, as are Macintoshes. Availability of software and prices are the two main criteria you want to consider when purchasing or obtaining different brands of computers.