73S1217F Data Sheet
DS_1217F_002
Table 4: Internal Data Memory Map
Direct Addressing Indirect Addressing
RAM
Addres
s
0xFF
0x80
0x7F
0x30
0x2F
0x20
0x1F
0x00
Special Function
Registers (SFRs)
Byte-addressable area
Byte or bit-addressable area
Register banks R0…R7 (x4)
External Data Memory: While the 80515 can address up to 64KB of external data memory in the space
from 0x0000 to 0xFFFF, only the memory ranges shown in Figure 2 contain physical memory. The
80515 writes into external data memory when the MPU executes a MOVX @Ri,A or MOVX @DPTR,A
instruction. The MPU reads external data memory by executing a MOVX A,@Ri or MOVX A,@DPTR
instruction.
There are two types of instructions, differing in whether they provide an eight-bit or sixteen-bit indirect
address to the external data RAM.
In the first type (MOVX A,@Ri), the contents of R0 or R1, in the current register bank, provide the eight
lower-ordered bits of address. This method allows the user access to the first 256 bytes of the 2KB of
external data RAM. In the second type of MOVX instruction (MOVX A,@DPTR), the data pointer
generates a sixteen-bit address.
14
Rev. 1.2
TERIDIAN [ TERIDIAN SEMICONDUCTOR CORPORATION ]
