attiny Turing machine

[Usmar A Padow]

Hi guys. I had an idea last night. How about making a Turing-ish machine using an attiny. The tape would be the SRAM. Only problem with the attiny is it only has 6 pins. I think I can use 4 pins and charleiplex them to display 8 bits using LEDs and use the other 2 pins for input. Is there a safe way to use pins for both input and output simultaneously?

[Boris A.]

Yes, you can switch between the two modes in code.

Or you could use :
  - an LCD module on i2c, 2 wires needed for output;
  - an attiny 2313 : 18 input/output pins.

Even better, why not code in assembly and use flash as a "tape" ? I.e. the normal mode for these ucons. I'm not really sure I understand what you are trying to achieve here. You still have to program the sram right ? Do you copy from flash ? What do you mean by Turing-ish ?

PS: technically, I think you only need 3 pins for 8 bits, if you do it right ...

[Usmar Padow]

the attiny 2313 has only 128 bytes od sram...

the reason why I dont want to program in normal assembly, is because I want to make a user-reporgammable computer

I have decided to use 4 pins for LEDs so I can display a nibble, and marco pinted me to using variable resistors to make a keyboard with a few keys to interact with the attiny85 and it is just connected to 1 pin

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[Marco]

Can I send the gerber files of the PCB to seeedstudio? :)