Updates slowed down a bit for the Saturn core of the MiSTer FPGA, with just two of them hitting developer Sergiy Dvodnenko’s GitHub in the last month.
Last week, Dvodnenko — aka SRG320 — pushed some fixes to the VDP1 graphics chip to fix sprite rendering problems in Battle Garegga and a crash caused by inaccurate VDP1 emulation on Rayman’s final boss. He also worked on the SCSP sound chip’s accuracy as well as the SH2 processor, which had a problem with starting games.
The SCSP fix seems to have perfected the core’s sound emulation. It now passes every test in the sound chip testing tool developed by Celeriyacon that Dvodnenko has been using for the last couple months.
“The core is the first system after the original hardware to pass all the SCSP tests,” said MiSTer Discord community member Zet-sensei last week.
Just like last month, Dvodnenko got some help from another developer on peripheral support. This time, it was Blue212, whose fix to the SNAC adapter’s Stunner light gun support got merged into the core by Dvodnenko on Sept. 29.
Developed by Blue212, the SNAC — which stands for Serial Native Accessory Converter — is a general purpose level shifter for use with MiSTer. One end of it is a USB connector while the other is the original console’s controller port. It allows users to play with original controllers, from gamepads to mice to light guns, on the MiSTer. SNAC adapters for a variety of consoles are sold on websites like Ultimate MiSTer.
The latest updates haven’t been added to the main MiSTer branch yet, so they must be manually applied after downloading them from the official MiSTer Discord server’s unstable nightlies channel.
The core’s GitHub lists the specific updates:
- SCSP:
- some fixes for accuracy (scsptest)
- VDP1:
- fix rendering of sprites with flipping (Battle Garegga)
- fix Distored sprite out of bounds check (Rayman final boss)
- SH2:
- fix the reset interrupt (problem with some games being the first one started in a play session)
- SNAC:
- fix Stunner and nothing connected to SNAC
Dvodnenko first released to the public a playable build of the core in May 2022 and has updated it many times since then. It was first added to the main MiSTer branch in October 2023, indicating that it was mature enough to be available to all MiSTer users rather than as an optional core that had to be added manually.
Anyone interested in supporting Dvodnenko can do so at his Patreon.
The MiSTer is a field-programmable gate array, a chip that can be changed by programming it to physically emulate retro video game consoles. It includes an SD card reader from which “cores” and games can be loaded.
The cores are the programming that tells the FPGA chip how to configure itself to reproduce the performance of a console. There are cores for a wide array of consoles, from the Atari 2600 to the PlayStation — and now the Saturn.
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