Status registers

Read from status registers. More...

Collaboration diagram for Status registers:

Functions
uint8_t	vdp_get_status (uint8_t reg)
	MSX Read from a VDP status register.

Detailed Description

Read from status registers.

Function Documentation

vdp_get_status()

uint8_t vdp_get_status

(

uint8_t

reg

)

MSX Read from a VDP status register.

Parameters

reg	VDP status register number. MSX : 0 MSX2: 0..9 If any other value was specified, behaviour is undefined.

Returns

Value of the VDP status register.

• If reg != 0, returns the value of the status register #reg
• If reg == 0, returns the value of STATFL instead of reading the status register #0 (S#0).

Note

The MSX SYSTEM interrupt routine reads S#0 to see if an interrupt due to VSYNC has occurred. Also, reading S#0 resets bit #7 (VSYNC interrupt flag) of S#0, so the latest value read from S#0 is stored in STATFL for other uses. Therefore, this function reads STATFL instead of S#0 if reg == 0.

See also

STATFL