CRISS is a 21st-century CP/M single-board computer based mainly on AVR microcontrollers. The CPU is a 20 MHz ATMEGA1284P, which imitates a 4 MHz Z80 through machine-code emulation. A pair of ATMEGA328s run the peripheral controller and a VGA output, so the CRISS can be used with modern monitors. True to its heritage however, the image is monochrome green-on-black, looking instantly familiar to users of Kaypro's, Osborne's and other contemporary CP/M machines.

Software is loaded through an SD card that holds floppy images. The CRISS can directly run programs written for the Kaypro II and Robotron 1715 computers, although other platforms can be supported as well with a software upgrade. 

Housed in a neat little case, the CRISS can communicate with standard PS/2 keyboards and serial printers. Even an Ethernet port is provided for those willing to experiment with network connectivity (a rare feature in the 1980s).

Features:

OS: CP/M 2.2 = programming languages, text processing, games, business software, ...

Instructions: Z80 (Zilog), extended with MUL, DIV, and floating-point, 1us LD r,r ops

Memory: 55 Kb TPA(!!) from 64 Kb SRAM + 128 Kb EPROM = 3 switchable user sessions!

Video: VGA (!) monochrome 24/25x80 or 30/31x64, 5 symb. sets, 160x96 px + sleep mode (!)

Storage: SD-card

Keyboard: PS/2, 2 layouts + PS/2 mouse (!)

Printer: YES, serial or LPT

Interfaces: RS-232, UART, Ethernet, GPIO

Real time clock

Single-tone melody generator with built-in speaker

Terminals emulation: VT100, Robotron PC1715, Kaypro II, ADM, Microbee, TRS-80, ...

8-bit AVR MCUs based, DIP only, no modules and development boards, 100% open project!

Join us at DISCORD: https://discord.gg/TZgxdAmskw

Take a look at: https://hackaday.io/project/181038-criss-cpm-8-bit-homebrew-diy-computer-avr-based

Official Web site: http://criss.fun