I wasn't ready to design circuit boards. Indeed, I'm still not ready. I don't think that I'll ever be ready but I had time and opportunity to push my limits.

After designing boards in Nov 2021 and Dec 2021, ordering boards in Dec 2021 and receiving boards in Jan 2022, I have only looked at them ...

I have two quick items which will otherwise get lost in style, memory map and address decode. If anything bores you then skip to the first memory map.

I forgot to mention the inclusion of six ground test points for the purpose of minimizing loop inductance when viewing signals with an oscilloscope ...

51x30 x 8x8 characters.

Oooh! Is your display is widescreen? Either way, you impress me at every opportunity.

Making video circuitry is currently outside of my ability.

Then G-d help the rest of us.

I'm mostly theory. In practice, AndersNielsen and many others are ahead of me.

Oh wow this ...

Totally Spies X-Powder

After going to the Sheepopolis Toy Exhibition, I discovered the improbably named Miraculous: Tales of Ladybug & Cat Noir . In the manner that ARM is a spiritual continuation of 6502, Miraculous is a spiritual continuation of Totally Spies. In particular, both are created by ...

Shortages are getting serious. Taiwan had a water shortage and many of the chip factories are now using reverse osmosis to reduce water consumption.

Neon, used in chip lithography, was disproportionately supplied by Ukraine but supplies may be disrupted. I assumed that Neon was condensed out of the ...

power lines double width

Firstly, discussing double width power lines on 2022/02/22 is amusing.

Secondly, I intend to prototype as two layer and deploy as four layer with inner power and ground. Dave L. Jones and GARTHWILSON both recommend that power and ground should run between 0.1 inch spaced ...

I planned to write about the chip shortage. We've had a helium shortage for years. Likewise with an avacado shortage. Now the shortages are getting ridiculous. Shipping container shortage. Toilet paper shortage. Used car shortage; partly due to the chip shortage halting car manufacture. GPU prices ...

I have a not so brief message to anyone working on their own computer design: Don't despair if it takes years to complete. I joined the 6502 Forum on Tue Aug 11, 2020 and was working on 64 bit extension for 6502 but unable to maintain interrupt performance as address-space scaled. After reading ...

GARTHWILSON: It occurred to me almost immediately after publication that I might be out by a factor of 10. I thought "Hopefully, one of the amateur radio enthusiasts corrects it. Otherwise, one of the pedants will jump on it." 6502 assembly programming requires a certain level of pedantry. Therefore ...

You're probably over-thinking this problem.

No, actually, I'm under-thinking the problem. The shift register solution requires four signal lines: clock, data, set bits live - and then a programming pulse with controlled duration. I considered bodging this into a NES input peripheral extension ...

I've been working on input peripheral boards. Now available and in stock:


XR0220 (untested): Possibly the world's first gaming hexpad. 20 button keypad which is compatible with most NES and SNES games.
XR0256 (untested): 16*16 keyboard matrix controller.
XR0225/N (untested, but I'd have to be ...