June 2019 – Catrin Labs

Chroni Part 3: Color Palettes

June 9, 2019August 4, 2020| fcatrin

The color palette can unequivocally identify a computer with a certain aesthetics, think of the vivid but few colors found in the ZX spectrum or the characteristic ’70ish colors found in the Atari to the grayish/blueish look of the C64. In short, the color palette gives the computer a certain personality. Choosing a color palette […]

Chroni Part 2: VRAM access

June 8, 2019June 11, 2019| fcatrin

The CPU can write or read the 128KB VRAM using a 16KB window at address $A000. There is a special register called VPAGE to select which 16KB is visible in that $A000 – $DFFF range of memory. This is a simple example to write to the first byte at VRAM VPAGE = $9009 lda #0 […]

Chroni Video Processor (Part 1)

June 8, 2019June 8, 2019| fcatrin

Finally Compy has a video processor and it is called Chroni! The name comes from “partners in time” and it was suggested by my friend Stuart Law as a variant of the British saying “Cronie, partners in crime”. Why partners in time? Because the CPU must operate in sync with the video processor and it […]