JOTEGO

(español abajo) Arcade systems have many memory chips working at the same time. Whereas a computer system of the same age will have all devices built around a RAM memory, arcade games had no single central memory. Each subsystem had access to its memory, which often was exclusive. This difference me

I'd like to discuss a technical topic this week: missing elements in emulators and, well, some FPGA cores. Let's use the palette memory of Side Arms for our case study. Side Arms uses a regular RAM chip to store colour palette values. The GPU decides which pixel has priority from the character, scro

This has been the FM week. I have fixed some NeoGeo sound issues, which have been released on MiSTer today and continued work on the YM3526 OPL sound chip. Let me talk about FM sound a bit. NeoGeo, Megadrive and Ghosts'n Goblins have something in common: FM sound chips built around the OPN Yamaha op

(español abajo) We are all in here because we want accuracy. We want no lag. We want the original speed. We even want the original glitches! And FPGA is the technology that provides it. FPGA allows you to make digital hardware at an affordable price. But what if I told you that you have used an emul

MRA files are now the standard way of loading ROM files into FPGA cores. Originally developed for the MiSTer platform, we have taken them to other platforms too via the command line mra tool. The MRA defines a list of files to be transferred to the FPGA. The order in which the files are transferred

Welcome back to one technical article. This time I'm going to talk about DMA (Direct Memory Access) in the CPS system. This aspect is completely ignored in emulators and has a large effect in the effective processor performance because if the DMA is active the CPU is stopped. The result is that emul

It's time for this month's technical post. With the Double Dragon cores we have experienced two games with very intensive use of ADPCM sound effects. Oh, and Double Dragon II even shares the same ADPCM chip than CPS1 games. I'd like to briefly explain how ADPCM worked, comparison to consoles and pro

A nice graphical effect is to have the characters go underneath elements in the screen. Like the soldier behind the palm tress in Commando. One way to create this effect is to have that background drawn directly on the sprite layer, using sprites as though they were tiles. That is the approach follo

Bionic Commando and CPS1 systems feature brightness control. Let's see how that works. Most arcade games have four bits for each colour component: red, green and blue. These four bits are each a digital signal which can be either 5 Volt or 0 Volt. Arcade boards connect resistors to these signals to