Imported from GitHub: kyllikki/eda-designs · commit 7ed05e5 · license MIT

Description

EDA designs

README

Simple As Possible Register Designs

The SAP computer by Ben Eater uses an 8bit register design based on 74LS173 which is replicated here as the first design.

I have an additional three designs based on slightly more accesible components but missing some functionality:

• The r bus enable ~RENABLE is unused in the SAP design so is unimportant

• more significantly the RESET functionality. This may not be necessary for the A, B or I(nstruction) registers as these are loaded by a program depending on usage but this is up to the reader to decide.

Design	BOM	Notes
Original	2 x 74LS173, 74LS245, 8xLED
273	74LS00, 74LS273, 74LS244, 8 x LED	No ~RENABLE
374	74LS00, 74LS374, 74LS245, 8 x LED	No RESET
377	74LS377, 74LS244, 8 x LED	No RESET or ~RENABLE

Although the 74LS244 is used in the design it is directly replacable with a 74LS245 I just happen to have lots of the 244 myself

The 74LS374 can be replaced with a 74HCT574 but you will then need 330R current limit resistors for the LEDs.

The schematics are Copyright 2017 Vincent Sanders released under CC BY-SA licence.