P5A: the ALU/Execution Units (2)

A project log for Discrete YASEP

a 16-bits YASEP computer (mostly) made of DIP/SOIC chips like in the 70s and 80s... with 2010's twists!

Yann Guidon / YGDESYann Guidon / YGDES 11/29/2015 at 17:530 Comments

This continues the previous log P5A: the ALU/Execution Units board and the operands

Once the 2 operands are selected and latched, the Execution Units can work. This YASEP has 3 EUs:

Overall, these 3 units perform most of the defined opcodes:

The P5A board has another distinctive feature: this is where you plug all the extensions, including SR (Special Registers) or IO (external memory, peripherals...). A MUX4 steers all those data to the output (8× 74HC253 with tristate output)