Video display

Replacement card for VGA LCD display. From left to right: Baud rate generator based on ATtiny84, Z80-SIO dual-USART for interfacing to Raspberry Pi (top right) and providing a second serial COM port.

The Raspberry Pi is running a special program turning it into a display generator.

Raspberry Pi emulation code https://github.com/eyalabraham/vga-rpi , baud rate generator AVR C code https://github.com/eyalabraham/baud-gen , and schematics in this Git repository.

Schematics in PDF: Bus buffers, IO address decode, Z80-SIO interface, BAUD rate generator, extra RS232 interface, component placement.

This repository https://github.com/eyalabraham/rpi-bare-metal/tree/master/vga-rpi implements the same emulation code but runs on the Raspberry Pi as Bare-Metal (no OS). This implementation removes the OS boot process and starts the emulation within a couple of seconds after power up.

A Mandelbrot fractal image generated by a small demo program. The program uses BIOS INT 10 graphics calls and should be portable to PC machines. The program has two version one for each color palette.

Screen shot of GW Basic.