2 years ago they wrote about a homemade computer with a processor on separate integrated circuits - BMOW1 . From an architectural point of view, he was very advanced, but extremely difficult to repeat.

The author of BMOW1 (Steve Chamberlin - Steve Chamberlin) developed the Nibbler computer, consisting of only 17 chips. Moreover, the processor there is also assembled on discrete logic.

Well, let's see what's inside.
')

Architecture

Nibbler - 4-bit processor. 2 ROMs are used to store microcode, 1 ROM for command memory - 12 bits address, 8 bits command.
RAM - 12 bits address, 4 bits data. Arithmetic considers the standard ALU 74181 (our analogue K155IP3).

With the outside world Nibbler communicates through the speaker, the standard text LCD screen HD44700.

Clock frequency - 2 MHz, each team takes 2 clock cycles. Of course, the inability to write code in memory imposes serious restrictions on the complexity of programs - but something has to be sacrificed for the sake of simplifying the design. In addition, it is impossible to read / write memory at an arbitrary calculated address - because corny there are no registers of the desired length.

A rare case when the computer scheme fits on one screen:

Design

Like BMOW - Nibbler is assembled by twisting wires, not by soldering.


In comparison with its predecessor:

Video work

I think, to assemble such a computer from discrete elements is completely within the power of everyone without spending half the life on it :-)