Dr.Beep ZX Spectrum-PC iface

A redesign of Dr Beep's project (http://trastero.speccy.org/cosas/JL/DrBeep/PC-ZX.html) for communicating a ZX Spectrum (and possibly related clones) to a PC. This redesign is based on a Raspberry Pico microcontroller instead of a PC and a paralell port

The RPi uses 8 GPIOs for I/O (D0-D7) and a SN74LVC245 as a bus transceiver, for communication with the ZX Spectrum. The rest of the logic is pretty much the same as the original design, including the ROM and the bus/port access logic, based on a few 74LSxx chips.

On this stage only the interface is presented. Two more components are needed: the uPython code to control the RPi, and the ROM routines adapted for the new interface. I expect to finish those two components, together with final tests of the board, in the next few weeks.

In the future, the project could include a Kempston joystick interface, a reset button and possibly a freeze button to allow for savestates and POKEs. Keep tuned for more news!