A weblog focused on interesting circuits, ideas, schematics and other information about microelectronics and microcontrollers.
A simple CP/M system fits in breadboard nowadays. Look at Grant's Work-in-progress version.
Photo: Grant Searle
The CPU is old good Z80 - with a little help of ATMegas. The Z80 is overclocked to 7.3728 MHz. It uses a Z80 SIO/2 chip to provide 2 serial ports. One serial port is available to connect to a PC running at 115200, the second port is connected internally to an ATMEGA88 processor which buffers the data between the CP/M computer and a PS/2 keyboard and an 80x25 character display.
The keyboard interface is internal to the ATMEGA88 processor, along with the serial buffers.
The 80x25 text video controller is created using an ATMEGA32 processor. This is based on a design by Daryl Rictor. Grant adapted the code to use the larger memory of the ATMEGA32 and modified it to make an 80 char display.
Read more about this amazing CP/M machine: Grant's home-designed CP/M machine