This is on NP21Kai (git version, from about a month ago)... Amaranth III, IV and KH all work fine, but the two older games have graphical corruption (all versions the .HDI files from the Neo Kobe set):
amaranth2.png
Amaranth (1) is virtually identical. Tried with GDC clock speed at 2.5 and 5MHz (Amaranth 2 detects if it's set to 5MHz and displays a message to change it back).
Haven't tried either on my 9821An yet.
You need to go to bios. Start the emulator. Select the option to Emulate select Reset and press the End key on your keyboard. In the BIOS in the second list of options to select GDC 2.5 MHz.
(https://img-fotki.yandex.ru/get/16178/2374305.1f/0_d1f60_cbad11f9_XL.jpg)
(https://img-fotki.yandex.ru/get/15504/2374305.1f/0_d1f61_f0c3bae_XL.jpg)
Yeah, thanks; I found that setting the emulated BIOS option to GDC 2.5MHz fixed it, even though using gdc.exe claimed it was being set to 2.5MHz. Both Amaranth 1 and 2 now work.