Blog – Catrin Labs

Compy FPGAs and how I got here

September 12, 2021September 12, 2021| fcatrin

This post is part of a series of three post about the recent updates on the FPGA implementation of Compy. Compy FPGA – Palettes and line buffers Compy FPGA – VRAM and Cornet CPU Compy FPGAs and how I got here (this one) I had a lot of problems in the way. A lot! Fortunately […]

Compy FPGA – VRAM and Cornet CPU

September 12, 2021September 12, 2021| fcatrin

This post is part of a series of three post about the recent updates on the FPGA implementation of Compy. Compy FPGA – Palettes and line buffers Compy FPGA – VRAM and Cornet CPU (this one) Compy FPGAs and how I got here Video RAM Simultaneous access to RAM from the CPU and the video […]

Compy FPGA – Palettes and line buffers

September 12, 2021September 12, 2021| fcatrin

A long time have passed since I started implementing Compy in FPGA, and I’ve made a lot of mistakes but also I’ve learned a lot. I knew a lot less about computer architecture and design than I thought I did! After being stuck for a long time with basic issues, these last weeks I’ve been […]

Output video modes for Chroni / Compy

November 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

December 18, 2019December 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

December 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

September 29, 2019September 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

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 […]