Purpose: Set/read bottom of system RAM
Call address: $FF9C (hex) 65436 (decimal)
Registers: .X = lsb of MEMSTR .Y = msb of MEMSTR Memory: system map Flags: .C = 0 -> set bot of memory .C = 1 -> read bot of memory Calls: noneResults:
Registers: .X = lsb of MEMSTR .Y = msb of MEMstr Memory: MEMSTR ($A05) Flags: none
Description: MEMBOT is used to read or set the bottom of system RAM, pointed to by MEMSTR ($A05). This call is included in the C128 for completeness, but neither the Kernal nor BASIC utilizes MEMBOT since it has little meaning in the backed memory environment of the C128. Nonetheless, set the carry status to load MEMSTR into .X and .Y, and clear it to update the pointer from .X and .Y. Note that MEMSTR references only system RAM (RAM0). The Kernal initially sets MEMSTR to $1000 (BASIC text starts here).
SEC JSR $FF9C ;get bottom of user RAM0 INY CLC JSR $FF9C ;raise it 1 block