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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 |