Saturn MiSTer Core Gets Tons of Updates in Last Month

There have been a flurry of updates to the Saturn core of the MiSTer FPGA over the last month now that its developer, Sergiy Dvodnenko — aka SRG320 — is in a safer part of Ukraine.

The new builds for single- and dual-RAM setups are not available in the main MiSTer branch — they must be downloaded from the unstable nightlies channel of the MiSTer’s official Discord server.

Dvodnenko has updated the core 10 times since SHIRO! last reported on his progress on Jan. 11. The core’s development Github lists all of the fixes:

• VDP1:
  -add support “Rotation 8” screen mode (Grandia, battle screens)
  -fix drawing of Scaled sprite with zero size (menu Vandal Hearts – Ushinawareta Kodai Bunmei)
  -add frame buffer rotation modes (Shienryu, Power Drift, Hang-On GP)
  -rework of drawing sprite with zero size (fix regression)
  -fix the drawing start position (flickering in Grandia intro, NBA JAM Tournament Edition)
  -fix MSB ON mode (Asuka 120% Limited, Zoop shadow)
• VDP2:
  -add support Color calculation window (Magical Drop III)
  -fix Extended color calculation (Linkle Liver Story transparency bug)
  -fix Color calculation in hires mode (Sonic Jam, menu)
  -fix Line window hit (Panzer Dragoon II Zwei, episode 3)
  -fix transparent window position (line on the left in Sonic Wings Special, Street Fighter Collection, Waku Waku 7)
  -fix DMA write to VRAM (missing tiles in Darius Gaiden)
  -fix Transparent shadow (menu Puyo Puyo 2)
  -fix Color calculation (playfield Kanzen Chuukei Pro Yakyuu Greatest Nine)
  -add support for rotation reading of frame buffer (Shienryu, Power Drift, Hang-On GP)
  -add support for single density interlace mode (Shienryu)
  -fix vertical scrolling changes in the middle of the screen (Shienryu)
  -fix latching of screen mode settings (Gokujou Parodius Da! Deluxe Pack)
  -allow CPU to access VRAM during Rotation parameter slots reading when RBGs are disabled (Senken Kigyouden)
  -fix vertical cell scroll function (Magical Night Dreams Cotton 2)
  -don’t update the vertical scroll value for NBG0/1 in the middle of the screen (Bug! regression)
• SCU:
  -fix A-BUS DMA with invalid address (Tactics Ogre-Let Us Cling Together)
  -fix DSP DMA to DSP program RAM (Shining Force III)
• SMPC:
  -enable RTC
  -add delay to abort INTBACK command (Terry Pratchett’s Discworld,Primal Rage)
• SH7604:
  -hold DMAC cycle during the external vector read cycle to avoid conflict (Croc – Legend of the Gobbos intro)
• DDRAM:
  -fix ddr3 controller (fixed some regressions)
  -rework ddram controller to speed up writing in time-critical game code (Sega Rally Championship 2 player battle)

Video Game Esoterica, as always, has been making videos showing off all the games newly working or working better with each update. His latest one was just uploaded today:

The sheer number of updates Dvodnenko has cranked out represents significantly progress on making the core emulate Saturn hardware as closely as possible. Before escaping Russian occupation in eastern Ukraine at the beginning of this year, there had been only occasional updates every month or two since he first released to the public a playable build of the core in May 2022.

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, at least in an early form, the Saturn.