9.7.3 TOS

Contents of the stack pointed to by the STKPTR register. This is the value that will be loaded into the Program Counter upon a RETURN or RETFIE instruction.

Note: The individual bytes in this multibyte register can be accessed with the following register names:
  • TOSU: Accesses the upper byte TOS[20:16]
  • TOSH: Accesses the high byte TOS[15:8]
  • TOSL: Accesses the low byte TOS[7:0]
Name: TOS
Offset: 0x4FD

Top-of-Stack Register

Bit 2322212019181716 
    TOS[20:16] 
Access R/WR/WR/WR/WR/W 
Reset 00000 
Bit 15141312111098 
 TOS[15:8] 
Access R/WR/WR/WR/WR/WR/WR/WR/W 
Reset 00000000 
Bit 76543210 
 TOS[7:0] 
Access R/WR/WR/WR/WR/WR/WR/WR/W 
Reset 00000000 

Bits 20:0 – TOS[20:0] Top-of-Stack

The individual bytes in this multibyte register can be accessed with the following register names: TOSU: Accesses the upper byte TOS[20:16] TOSH: Accesses the high byte TOS[15:8] TOSL: Accesses the low byte TOS[7:0]