Bridging the analog gap

Bridging the analog gap

The investigations up to this point remained entirely in the digital domain. Waveforms like the ones shown in the VLM5030 gate-level design validation and lock-step comparison post were derived from the PCM data right before it enters the DAC. This is most suitable to...
Analysis and a hypothesis

Analysis and a hypothesis

What could cause that the VLM5030 partially behaves non-deterministic for certain frames? The usual suspects are incomplete reset and …randomness. Lots of internal states / flip-flops aren’t affected by the RST input, so that could be a cause for repeated...
Extract, reconstruct, simulate … repeat

Extract, reconstruct, simulate … repeat

When I started to search for the random generator the first challenge was the decision where to begin with. Looking at the die, there are not many landmarks that provide clear guidance. The ROMs are quite prominent due to their regular structure, but they don’t...
ROM extraction

ROM extraction

The previous post introduced a tracing procedure to extract logic gates from VLM5030’s layout information. This post shows how the procedure can be extended to extract VLM5030’s embedded ROMs. Simple ROMs The image below shows a portion of the sequencer...
Logic gates extraction

Logic gates extraction

The technology We need to set the stage first for this post. The VLM5030 is built from depletion-load NMOS logic. This means there are basically two types of devices: Enhancement-mode NMOS transistors for shorting a node to GND (or forwarding voltage between two...
Randomness on a microscopic level

Randomness on a microscopic level

Quite a couple of Konami cores use the VLM5030 chip to generate human-like speech for in-game effects. While the replacement design created for the replay library does its job, it still falls behind the audio of an original chip. This is mainly due to the fact that...
It’s-a me, Mario!

It’s-a me, Mario!

There has been quite a lot of work going on in the background with the FPGA Arcade project, not the least of which is a host of new core releases. As you may have guessed from the image, the NES is now available for the Replay and MKR Vidor4000 platforms. This version...
Acorn Electron Core

Acorn Electron Core

A little over 34 years ago, Acorn Computers Ltd released a budget version of the BBC Micro, the Acorn Electron. For a time it was apparently the best selling Micro in the United Kingdom, although in more recent years the Electron seems to be overshadowed by its big...
New Amiga Core

New Amiga Core

A new Amiga core was just released with a fix on the RTG interrupt + new RTG driver that handle the interrupt correctly....
New Amiga Core

Amiga AGA core stable release

I’ve released a new version of the Amiga core (https://github.com/FPGAArcade). New features : 48M XRAM mapped as Chip and all chipset DMA pointers support 64M addressing (optionally enabled in OSD / .ini file) CPU cache stable – 2 way I + D with full...
New Amiga Core

Cache and RTG operational in Amiga core

A lot of work has been done both on the CPU to increase compatibility, and the core to get the cache working and timing closure. The design is completely constrained and this results in a very stable platform Latest features: 2K Instruction plus 2K Data cache with...
New Amiga Core

Amiga core update – Blitter issues and chipset timing

The AGA core is pretty stable now, but one issue which has been haunting me for ages is some blitter operations go wrong and leave garbage on the screen. I’ve been working with Jim Drew, who pointed me at some source code released by DMA designs for Menace...
New Amiga Core

Amiga core update

I made a few minor improvements to border sprite behaviour (fixes Banshee AGA). The core is in the Amiga news thread in the forum. I intend to get the release SVN area sorted out in the next day or so…
New Amiga Core

Amiga core update

I’ve been testing a new version of my Amiga AGA core. It’s checked into the private repository. I’m working this week to make binary releases (and source ASAP) on the public mirror.   The MIST AGA project has received some great updates...