SoC

The WonderSwan SoC is a single-chip solution powering the entirety of the system's hardware - containing the CPU, most peripheral logic, as well as the internal RAM.

There exist three variants of the SoC:

• ASWAN, used in the WonderSwan,
• SPHINX, used in the WonderSwan Color,
• SPHINX2, used in the SwanCrystal.

A fourth variant, CAIRO, was planned. It was designed as an ASWAN with a doubled clock speed and a built-in ADPCM decoder, but is not known to have been licensed for any commercial product.

I/O ports

System Control ($A0)

7  bit  0
---- ----
C??? swcl
|    ||||
|    |||+- Boot ROM lockout: 0 = off, 1 = on
|    ||+-- Color model: 0 = no, 1 = yes
|    |+--- Cartridge ROM width: 0 = 8-bit, 1 = 16-bit
|    +---- Cartridge ROM wait state: 0 = +0 cycles, 1 = +1
+--------- Cartridge bus test OK

System Control 2 ($60, color)

7  bit  0
---- ----
c4C. i.sl
|||  | ||
|||  | |+- Cartridge clock speed?
|||  | +-- Cartridge SRAM wait state: 0 = +0 cycles, 1 = +1
|||  +---- Cartridge I/O wait state: 0 = +0 cycles, 1 = +1
||+------- 1 = 4bpp "chunky"; requires all previous
|+-------- 1 = 4bpp; requires all previous
+--------- 0 = mono, 1 = color; also controls access
           to WSC-specific features (extra RAM, DMA, etc.)

System Control 3 ($62, color)

7  bit  0
---- ----
S... ...p
|       |
|       +- 1 = Request power off
+--------- 0 = WonderSwan Color (SPHINX)
           1 = SwanCrystal (SPHINX2)

After setting the "request power off" bit to 1, halting the CPU will cause the console to shut down.

TODO: $AC bit 0 seems to also shut down the console.

System Test ($A3)

Note that this port is only writable as a byte - writing a word to $A2 does not write to this byte.

7  bit  0
---- ----
.... u?vh
     | |+- Enable HBlank Timer test
     | +-- Enable VBlank Timer test
     +---- Enable UART test

The timer tests ignore the reload value and clock the timers at 3072000? Hz. The enable bit is still respected.

The UART test disables the 9600/38400 baud clock divider, instead operating the EXT port's UART lines at 192000 baud.