bitfixer
Veteran Member
Sure, I'll have those schematics ready for you in a couple of days.
If you want to interact with the computer through a serial terminal, with this design you can do a simple Z80 computer with 4 chips - an Atmel ATmega16 uC, a 128k SRAM chip (I'm using the lower half only), a Z80, and an RS232 line driver. The Atmega16 has a built-in UART and can relay characters back and forth from the Z80. To solve the timing issues, the ATmega16 listens for the IORQ signal (when the Z80 wants to interact with IO), and immediately asserts WAIT. I use IO port 0 for terminal I/O, and relay each character received from the Z80 over the UART.
To add the keyboard and composite display capability requires a couple of logic chips and two additional microcontrollers.
I'll let you know when I have the schematics ready.
If you want to interact with the computer through a serial terminal, with this design you can do a simple Z80 computer with 4 chips - an Atmel ATmega16 uC, a 128k SRAM chip (I'm using the lower half only), a Z80, and an RS232 line driver. The Atmega16 has a built-in UART and can relay characters back and forth from the Z80. To solve the timing issues, the ATmega16 listens for the IORQ signal (when the Z80 wants to interact with IO), and immediately asserts WAIT. I use IO port 0 for terminal I/O, and relay each character received from the Z80 over the UART.
To add the keyboard and composite display capability requires a couple of logic chips and two additional microcontrollers.
I'll let you know when I have the schematics ready.