Siemens EF 88H Series Manual de usuario descargar pdf (Pagina 11)

Semiconductor Group 3 - 3

Memory Organization

3.2 Data Memory

The data memory space consists of an internal and an external memory space. The SAB 80C517A

contains another 2 kByte of On-Chip RAM above the 256 Bytes internal RAM of the base type

SAB 80C517. This RAM is called XRAM in this document.

– External Data Memory

Up to 64 Kbyte external data memory can be addressed by instructions that use 8-bit or 16-

bit indirect addressing. For 8-bit addressing MOVX instructions in combination with registers

R0 and R1 can be used. A 16-bit external memory addressing is supported by eight 16-bit

datapointers. Registers XPAGE and SYSCON are controlling whether data fetches at

addresses F800

to FFFF

are done from internal XRAM or from external data memory.

– Internal Data Memory

The internal data memory is divided into four physically distinct blocks:

– the lower 128 bytes of RAM including four banks containing eight registers each

– the upper 128 byte of RAM

– the 128 byte special function register area

– a 2Kx8 area which is accessed like external RAM (MOVX-instructions), called XRAM

implemented on chip at the address range fromF800

to FFFF

. Special Function

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Siemens EF 88H Series Manual de usuario Pagina 11