“Pinstrap support” refers to an alternate mode of execution where code is executed from 4000:0000 or 4000:0010 instead of executing the full boot ROM logic and jumping to FFFF:0000. It is documented in more detail on the WSdev wiki.

The Pocket Challenge V2 uses the same ASWAN SoC as the “mono” WonderSwan, but it repurposes the bit 1 pinstrap (code starts at 4000:0010) in order to bypass the Bandai splash screen, seeing as it is instead a Benesse product. This page documents how to use Wonderful to create a cartridge image that boots on the PCv2.

To add a stub at 4000:0010 which jumps to your program, replace $(WF_CRT0) in your Makefile with $(WF_CRT0) $(WF_CRT0_PINSTRAP1).

For 4000:0000, add $(WF_CRT0_PINSTRAP0) instead. You can also add both.

The pinstrap mode omits certain hardware initialization code that occurs in the boot ROM. In particular, the LCD display driver is never enabled. To solve this, add the following code to your program:

outportb(WS_LCD_CTRL_PORT, inportb(WS_LCD_CTRL_PORT) | WS_LCD_CTRL_DISPLAY_ENABLE);

The default pinstrap stubs disable the boot ROM before jumping to user code, as the pinstrap mode starts with the boot ROM overlaid on top of the cartridge area at 0xFF000 - 0xFFFFF. If you'd like to instead access the boot ROM contents, you have to perform the following steps:

• Replace $(WF_CRT0_PINSTRAP1) with $(WF_CRT0_PINSTRAP1_UNLOCKED).
• Add rom_reserve_bootrom_area = true to the [cartridge] section of wfconfig.toml. This will reserve the final 8 KiB of the cartridge space, preventing any data assigned to the linear ROM bank (but not assigned to ROM0 or ROM1 banks) from being placed there.