Re-started PCB design, in SMD

A project log for Isetta TTL computer

Retro computer built from TTL, with 6502 and Z80 instruction set. Includes video, file, and sound system. No microprocessor.

roelhroelh 01/28/2024 at 09:200 Comments

Since I last worked on the PCB design, there have been many changes.

And after looking at the availability of the chips, I found that several of them were not in stock (in DIL version). And since the design has become faster, it is not as easy any more to switch between the TTL logic families, because for many chips, the speed is critical.

This made me decide to switch to SMD devices. Only the microcode flash chips will stay in DIL, so they can be easily taken out to program them (although there will be a system to program them while they stay on the board).

Here is a preview of the new design:

Dimensions are 12 x 15 cm ( 4.7 x 5.9 inch). It will be a 4-layer board. It is designed to fit in a Hammond RM2055S enclosure.