Donkey Kong Country 2 has a pretty well-known bug in the old SNES emulator ZSNES where some stages have spinning barrels that don’t work properly. One of the earliest pictured here, in the first stage of Krem Quay (third world):
After you jump into the barrel, you’re supposed to be able to completely control its rotation by pressing left and right on the d-pad, with the barrel only rotating while you’re holding left or right.
This is the seventh and final post in a series on emulating the main Sega Genesis sound chip, the YM2612.
Part 1 - Interface Part 2 - Phase Part 3 - Envelopes Part 4 - Digital Output Part 5 - Analog Output Part 6 - LFO This post will cover the envelope generator’s SSG-EG mode.
This is the sixth in a series of posts on emulating the main Sega Genesis sound chip, the YM2612.
Part 1 - Interface Part 2 - Phase Part 3 - Envelopes Part 4 - Digital Output Part 5 - Analog Output This post will cover the hardware timers, the LFO (low frequency oscillator), and synthesized effects powered by the LFO.
This is the fifth in a series of posts on emulating the main Sega Genesis sound chip, the YM2612.
Part 1 - Interface Part 2 - Phase Part 3 - Envelopes Part 4 - Digital Output This post will cover a few aspects of the YM2612’s audio hardware, particularly the DAC (digital-to-analog converter), that are not strictly related to sample generation but do noticeably affect the sound of the final output.
This is the fourth in a series of posts on emulating the main Sega Genesis sound chip, the YM2612.
Part 1 - Interface Part 2 - Phase Part 3 - Envelopes This post will describe how the chip computes operator and channel outputs given the phase generator and envelope generator outputs.
This is the third in a series of posts on emulating the main Sega Genesis sound chip, the YM2612.
Part 1 - Interface
Part 2 - Phase
This post will describe how the ADSR envelope generators work.
ADSR Each of the YM2612’s 24 operators has its own ADSR envelope generator that automatically adjusts the operator’s volume over time.
This is the second in a series of posts on emulating the main Sega Genesis sound chip, the YM2612.
Part 1 - Interface
This post will describe the FM synthesis channels’ phase generators.
Phase Generation Each of the YM2612’s 24 operators contains a phase generator and an ADSR envelope generator.
This is the first post in a series on emulating the main Sega Genesis sound chip, the Yamaha YM2612 FM synthesis chip, also known as the OPN2.
To date, the YM2612 is pretty easily the most difficult-to-emulate sound chip that I have worked on.
The Famicom allows cartridges to modify the console’s audio signal between the APU (audio processor) and the TV. Most games don’t do anything with this capability, but some games included expansion audio chips on the cartridge board to enable enhanced audio beyond what the console is normally capable of.
This is the second of two followups to my post on the Sega CD PCM chip. Where the last post described a way to improve audio quality by applying an audio filter to final mixed PCM chip output, this post will describe an audio enhancement that improves audio quality by changing how the emulated chip itself generates samples.