Here on CircuitGizmos one of the popular products is the CGCOLORMAX2, or as we call it the ColorMax. The ColorMax is a VGA color-output retro computer that is a lot like a 1980’s home computer (TRS80, C64, etc) running on modern hardware.

The ColorMax is based on (and compatible with) Geoff Grahm’s Color Maximite design. This retro computer is very similar to the computers that sold in great number in the 80s. The ColorMax powers up to a BASIC prompt, much like those earlier machines. The BASIC is much more advanced, however. The ColorMax’s BASIC doesn’t require line numbers. It is closely compatible with MSBASIC, but has a lot of extensions. BASIC (4.5) runs at about 30,000 lines per second.

The ColorMax can be plugged into a VGA monitor (8 colors at 480×432 pixels) and a PS2 keyboard. The ColorMax has an SD card slot for up to 32G of program and data storage. The 32 bit processor takes care of the video and SD card interfacing. The VGA output can display graphics or 33 lines by 80 characters of text, or a combination of the two. Graphics support in BASIC includes pixel, line, rectangle, and circle commands. Custom fonts, BLITs, SPRITEs, and BMP files are also supported. As an alternative to VGA, monochrome composite video (in PAL or NTSC) is supported.

More than just a fast and capable retrocomputer, the ColorMax supports a serious number of ways to interface to the real world. A dual-row connector on the back of the board has 20 lines that support digital i/o, analog input, frequency, period, and counting. 20 additional lines are arranged in an area centered on the top of the board in a pattern compatible with the use of Arduino Shields. Analog output and even sound can be achieved by the use of the two PWM outputs.

CGCOLORMAX2 Interface Circuits

A number of communications protocols are implemented. These include I2C, serial (RS232 and RS485 with a suitable driver chip), SPI, 1-Wire and CAN (with suitable driver). The ColorMax has an area on board where the support/driver chips can be installed.

The ColorMax can operate as a stand-alone retrocomputer, or can be linked to a PC (via USB) for development. The time-keeping facility of the on-board BASIC is augmented by the battery-backed-up Real Time Clock.

CGCOLORMAX2 Technical Information

Here is a link to the language manual:
https://circuitgizmos.com/documentation/mmbasic-language/

Next blog: Relay control.