[sdiy] Yamaha CS-60 issues

[Gordonjcp]

On Tue, Oct 06, 2020 at 07:33:17PM +1000, Adam Inglis (sdiy) wrote:
> 
> Interesting points Mattias!
> 
> What exactly did these chips do that could not otherwise be done?

Cram a bunch of functionality into a single chip, instead of a postcard-sized piece of PCB.

Compare the PCB of the Sinclair ZX80 from around the same time:

https://www.8bity.cz/wp-content/uploads/2011/05/ZX80R_najdi_10_rozdilu_thumb.jpg

with the PCB from the ZX81 where all the "glue logic" was crammed into a single Ferranti ULA:

https://upload.wikimedia.org/wikipedia/commons/thumb/b/b7/Sinclair_ZX81_PCB_Top.JPG/800px-Sinclair_ZX81_PCB_Top.JPG

You'll probably find that Yamaha's "custom" chip was similar to the off-the-shelf ULA used in the ZX81.  All the gates and stuff are there, they just need a couple more layers of metal to wire them up for the user application.

-- 
Gordonjcp