Experimental computer for schools

The computer is a small desk-top machine designed for teaching schoolchildren how computers work and how to use them. It works in decimal notation and has a powerful instruction set which includes 3-address floating-point instructions implemented as `extracode¿ subroutines. Addressing can be absolute, relative or indirect. For input it uses a capacitive touch keyboard, and for output and display, a perfectly normal t.v. receiver is used. Another input/output device is an ordinary domestic tape recorder, used mainly for long-term storage of programs. To make the operation of the machine easy to follow, it can be made to stop at certain stages in the processing of an processing of an instruction and automatically display the contents of all registers and storage locations relevant at that time. The paper gives a description of the machine and a discussion of the factors that have influenced its design.