Some steps in bank switching and crtc circuits - crtc pixel clock generator - 2k ram, enabling logic (heavily incomplete) - other 2k ram, annotation regarding data bus

Add PDF export script.

Add daughterboard schematics.

Embed new sheets and fix symbols.

Add GPIO uPD8255 wiring for bank switching.

Specialize generic IO sheet to SIO (serial) related.

Add address wires for SIO.

Fix grid aligment for SIO symbol.

README: PCB model from silk screen

Correction in speaker address annotation