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#tinytapeout

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Had some fun testing Ricardo Nunes's 12bit SAR ADC on #TinyTapeout 7 this afternoon.

A SAR ADC is a nice mixed signal example, with the digital section coordinating the binary search of an internal DAC, homing in on the input signal.

Glad I could test it myself and see it working!

Tapeout as a handicraft seems to have died out not long after there were computers "bootstrapped" for CAD. It's pretty eye-opening to look back on the early history of integrated circuits now: jocelynhyt8 on Instagram has made an incredible reproduction of some MOS 6502 masks that give a sense of complexity:
instagram.com/jocelynhyt8/p/DB

Here's an era-appropriate MOS SRAM mask to compare:
computerhistory.org/revolution

I wonder if any hobbyists have tried something like this for #tinytapeout?

Continued thread

This is the QSPI clock being output from my TinyQV design on #TinyTapeout 06.

It's a 32MHz clock, which should be within spec of the Tiny Tapeout outputs, which are rated to 33MHz.

As you can see, a couple of the clocks are rather low. This does just about work, but definitely warranted further investigation!

Continued thread

In the video above, it is acting as an 8 bit shift register with feedback, so in theory, we could build another layer now :D

I also did a time multiplexed nand gate on #tinytapeout 4, but then I didn't have the shift registers so I could only fit 128 bits of state compared to the 880 (in 2 tiles) here.

Of course, the tradeoff is time. Me and a friend think we will be able to fit an RV16I on this, but it will run at literal HZ with the ASIC clocked at MHz

Continued thread

What is it you may ask? It is a time multiplexed NAND-gate and a giant shift register. Schematically, it looks like this.

Every clock cycle, it can read a value from the top of the shift reg to either the left or right operand, and write an input or the current NAND output back into the shift register.

This is able to emulate any circuit with <880 bits of state+wires, but it won't be fun to program, nor fast.