The applets in this chapter demonstrate a simple 8-bit microprocessor, called PRIMA, built from the Hades register-transfer-level simulation components. The processor is used as a first example of the von-Neumann architecture in our introductory lectures on computer architecture.

As its name implies, the primitive machine is a minimal accumulator machine with just four registers (accumulator, program counter, instruction register, address register) and a main-memory of 256x8 bits. The instruction set and encoding is so simple that the control unit (stw for "steuerwerk" in German) consists of just four flipflops and a few gates.

	PRIMA processor (primitive machine)	applet	webstart	print
	PRIMA sequencer	applet	webstart	print
	PRIMA Steuerwerk (control unit)	applet	webstart	print
	PRIMA processor (increment/decrement loop)	applet	webstart	print
	PRIMA processor (factorial calculation)	applet	webstart	print