SAM

The SAM or Synchronous Address Multiplexer is a chip that controls access to RAM memory by the 6809 CPU and the VDG (Video Display Generator).

SAM Registers

Address	Shorthand name	Function	Effect
FFC0	V0CLR	SAM V0 bit clear
FFC1	V0SET	SAM V0 bit set
FFC2	V1CLR	SAM V1 bit clear
FFC3	V1SET	SAM V1 bit set
FFC4	V2CLR	SAM V2 bit clear
FFC5	V2SET	SAM V2 bit set
FFC6	F0CLR	SAM F0 bit clear
FFC7	F0SET	SAM F0 set bit	add $200 to video offset
FFC8	F1CLR	SAM F1 clear bit
FFC9	F1SET	SAM F1 set bit	add $400 to video offset
FFCA	F2CLR	SAM F2 bit clear
FFCB	F2SET	SAM F2 set bit	add $800 to video offset
FFCC	F3CLR	SAM F3 bit clear
FFCD	F3SET	SAM F3 set bit	add $1000 to video offset
FFCE	F4CLR	SAM F4 bit clear
FFCF	F4SET	SAM F4 set bit	$2000 to video offset
FFD0	F5CLR	SAM F5 bit clear
FFD1	F5SET	SAM F5 set bit	add $4000 to video offset
FFD2	F6CLR	SAM F6 bit clear
FFD3	F6SET	SAM F6 set bit	add $8000 to video offset