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SAM
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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 |