Notices by Bread80 (bread80@mstdn.social)

I've been wondering what the 'SP' on the SP/0 key does on the #Datapoint2200 keyboard. Then I realised that the keyboard logic board returns ASCII so the secret will be in the schematics. And for most keys the logic just twiddles a single bit. So top row number keys convert to the one bit different ASCII characters.

And what does '0' convert to? SPACE!! So SHIFT-0 returns a space character. I'm wondering if any other keyboards had this quirk?

@haitchfive I’m somewhat surprised that (some) older processes can’t be retained, cost reduced. They’d be very useful for short run/hobbyist designs (versus the patented cutting edge technology).

Surely lower factory cost must be useful for something? Not every chip needs ultra dense ultra small transistor size.

RIP Z80 🥲

End of life notification letter:
https://www.mouser.com/PCN/Littelfuse_PCN_Z84C00.pdf

That’s what I call a good start to the weekend 🙂🙂🙂

The only soldering error was a short between power and ground on the USB power connector.

Design wise the backplane has a couple of footprint issues, and my attempt to keep the board smaller by placing components under and between the cards is proving less than ideal in practice. The taller components are actually fitting between the cards but it looks messy and there’s potential for damage from soldered pins.

#AmstradModular #AmstradCPC

@mos_8502 @NoelsRetroLab @msh I’m probably spoilt because I’ve been looking at the Enterprise design. It can put any 16k memory block into any bank. And video gets a dedicated 64k block.

In contrast the Amstrads available options are very limited. Also, the restriction to having video in the base 64k. And the system (effectively) also has to go in the base 64k.

Enterprise designed this in from the start. The Amstrad came later but didn’t even consider it.

@NoelsRetroLab @mos_8502 @msh The more I learn about the Enterprise the more disappointed I become that it is so poorly understood.

Bitmap, character and attribute graphics. Multiple video modes on screen *at the same time*, (basic) video pass through capabilities. Just incredible.

@NoelsRetroLab @msh @mos_8502 I think the IO decoding is one of the Amstrads biggest flaws (along with the RAM banking schema).

But they were far from the only company at the time to hack things to keep the cost down.