| Function | Address | Description |
|---|---|---|
| MEMBOT | FF9C | Set bottom of memory |
This routine reads or writes the bottom of memory.
When the Carry flag is set then the bottom memory address is read into the X, Y index registers.
When the Carry flag is clear then the bottom memory address is set to the address in the X, Y index registers.
The value is stored in the MEMSTR variable at 0x281.
Default values
| Machine | Value |
|---|---|
| C64 | 0x0800 |
| V20 unexpanded | 0x1000 |
| V20 with 3K expansion | 0x0400 |
| V20 with 8K or more | 0x1200 |
Example:
Move bottom of memory up 1 page
SECRead memory bottom
JSRMEMBOT
INY
CLCWrite memory bottom
JSRMEMBOT