A “fourth generation” microcomputer, in the context of this Workshop, is regarded as a physically small machine, with the Central Processing Unit (CPU) and other specialized logic circuits contained on single Very Large Scale Integration (VLSI) chips. For most applications, the “system”, which includes the microprocessor, will be assumed to be configured with a minimum of 640 kb of Random Access Memory (RAM), a fixed or “hard” disk of 10–20 mb storage capacity, a flexible (floppy) removable diskette of (usually) at least 360 kb of storage capacity, and a printer-plotter (dot-matrix). Ideally, the microprocessor should have the ability to handle both 8-bit and 16-bit data and instructions. This system configuration now costs less than $5000 (US), and costs are being reduced rapidly. Peripherals useful to a geologist include a plotter, a digitizing tablet, a color monitor, and communication devices, the addition of which may bring the cost of the system to about $10,000 (US). Machines with full 32-bit capabilities, although more costly, are becoming available.