Autor: fcatrin | Catrin Labs

Output video modes for Chroni / Compy

Noviembre 22, 2020| fcatrin

The FPGA implementation of Compy has started, and it’s been a good way to confirm if the design ideas are feasible or not. One of the goals for Compy is to have a 4:3 display mode suitable for porting games from other systems using the 320×240 resolution as base as well as allowing processors like […]

Advanced Audio for Compy: FM synthesis and more

Diciembre 18, 2019Diciembre 18, 2019| fcatrin

As I said in my post about the dual POKEY included with Compy, I’ve been in the search of the advanced audio option for this 8 bit computer and I finally have made a decision! But as I love telling stories and retrieving some knowledge from them I will explain the whole process, the candidates […]

Porting games to Compy and its dual CPU

Diciembre 12, 2019| fcatrin

One of the goals for Compy is not only to provide a computer for new retro-games, but also to port existing games from different computers of the 8-bit era adding improved options for graphics and sound. One of the key elements to help on this goal is the dual CPU feature, the system will boot […]

POKEY and the future of Audio in Compy

Septiembre 29, 2019Septiembre 29, 2019| fcatrin

Today this project has reached a milestone: For the first time there is a full program running on Compy, not just a simple test code to check if some feature is working or not, but an application that uses several areas of this computer: the operating system, storage access, screen and keyboard handling, and more […]

Chroni Part 3: Color Palettes

Junio 9, 2019Agosto 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

Junio 8, 2019Junio 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)

Junio 8, 2019Junio 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 […]

Compy system architecture and video display

Abril 22, 2019| fcatrin

Before reading this entry I recommend you to read this introductory post to understand how video display works. I’ve seen several attempts to make new video display hardware for older computers or processors, and many of them have taken the approach to focus on the hardware first. Although I think this is the realistic approach, […]

Early Computer Architecture and Video display generation

Abril 22, 2019Abril 22, 2019| fcatrin

Sometimes we think that we know a lot of how computers work because we know how to code for them at a very low level – directly to the chips registers – we imagine our code almost driving every pixel on the screen, but digging into how to make the display work prove me that […]

CLC-88 Compy – The 8 bit computer

Abril 11, 2019Abril 13, 2019| fcatrin

Now it’s time to start making some decisions for the 8-bit computer. One of the hardest decisions is what CPU to use, because any option would leave out half of the potential coders. Most of the coders with asm abilities are skilled in only one of the two most popular processors, the 6502 or the […]