Build your own Computer CPU using Logic & Memory, before microprocessor's advent

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• published: 12 Feb 2013
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APOLLO181 Homemade 4-bit CPU Website: http://ygg-it.tripod.com/index.html Copyright © 2012 Gianluca G. Italy. All rights reserved. APOLLO181 is a homemade didactic 4-bit CPU made exclusively of TTL logics and bipolar memories. All employed chips are described in the Bugbook® I and II, in particular the 74181 Arithmetic and Logic Unit. After having intensively explored the Z80 CPU, I decided to design and make a processor from scratch by myself. The Bugbooks® volumes written by Dr. Peter R. Rony in 1974, Virginia, (which were my first study books) inspired and encouraged me to realize this. Peculiarity of APOLLO181 is the effective programmability: like real processors it can be instructed to perform high speed operations at different times and conditions, while exchanging data with the outside world. You will remain astonished to perceive how nowadays electronic components and computers are thousands of times smaller, faster, lighter, more integrated and cheaper, but you can still recognize in them many of the basic principles of operation that you will find in this project. I'm very delighted that Dr. Peter Rony, to whom I have recently communicated this project, has defined my APOLLO181 "a labour of love". Gianluca G., May 2012, Italy APOLLO181 Processor Specification Type: didactic 4-bit minicomputer CPU Designer: Gianluca G., Italy Style: retro-styled 1974 Bugbook® era Release date: June 2012 Technology: TTL 74S Schottky Data word size: 4-bit Instruction word size: 8-bit On-board RAM: 256 byte, bipolar SRAM On-board ROM: 1K-bit, bipolar fuse PROM ALU type: 74S181 Number of basic instructions: 16 (plus 32 arithmetic-logic operations) Addressable memory locations: 256 Clock frequency (max): 3 MHz Processor speed (max): 0,75 MIPS Clock cycles per instruction: 4 Time for register transfer: 2,7 µs Interrupt levels: 256 (without RTI) Number of internal registers: 16 (expandable to 32 using I/O ports) Number of I/O ports: 16 (plus 1 D/A Output) Audio: 4-bit DAC with internal speaker Number of integrated circuit: 60+ DIL Board weight and size: 3,2Kg (7,05lb); 300x300 mm (11,8x11,8 in) On board Power Supply (V/I): 5V / 3150 mA (35 Watt transformer) Everything you see in the video is the result of fifteen months of work (or fun?!). All data reproduced in the video are for educational and non-commercial purpose, following fair-use guidelines. Music is royalty-free for noncommercial. See license in the titles. Text and images from original typewritten Bugbooks I and II in 1974 are permission courtesy of Dr. Peter R. Rony, the original author and sole copyright owner of the Bugbooks I, II, IIA, III, V, and VI. Texas Instruments chip's data are Texas Instruments Copyright and reported by Courtesy of Texas Instruments.