SAB80C515A-5 SIEMENS [Siemens Semiconductor Group], SAB80C515A-5 Datasheet - Page 10

• Manufacturer Part Number: SAB80C515A-5
• Description: 8-Bit CMOS Single-Chip Microcontroller Family
• Manufacturer: SIEMENS [Siemens Semiconductor Group]

3.2
The data memory space consists of an internal and an external memory space. The SAB 80C515A
contains another 1 kByte of On-Chip RAM additional to the 256 Bytes internal RAM of the base type
SAB 80C515. This RAM is called XRAM (’eXtended RAM’) in this document.
3.3
All registers, except the program counter and the four general purpose register banks, reside in the
special function register area. The special function registers include arithmetic registers, pointers,
and registers that provide an interface between the CPU and the on-chip peripherals. There are
also 128 directly addressable bits within the SFR area.
All special function registers are listed in table 3-1 and table 3-2.
In table 3-1 they are organized in numeric order of their addresses. In table 3-2 they are organized
in groups which refer to the functional blocks of the SAB 80C515A.
Semiconductor Group
– External Data Memory
– Internal 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 a 16-bit
datapointer. Registers XPAGE and SYSCON are controlling whether data fetches at
addresses F800 H to FBFF H are done from internal XRAM or from external data memory.
The internal data memory is divided into four physically distinct blocks:
–
–
–
–
Data Memory
Special Function Registers
the lower 128 bytes of RAM including four register banks containing eight registers each
the upper 128 byte of RAM
the 128 byte special function register area
a 1Kx8 area which is accessed like external RAM (MOVX-instructions), implemented on
chip at the address range from F800 H to FBFF H . Special Function Register SYSCON
controls whether data is read from or written to XRAM or external RAM.
3-3
Memory Organization