SDA5250 Datasheet, PDF (49/143 Pages) Siemens Semiconductor Group – TVTEXT 8-Bit Microcontroller

SDA 525x
6.3.2
Memory Organization
The processor memory is organized into two address spaces. The memory spaces are:
– Program memory address space
– 256 byte plus 128-byte internal data memory address space
– Extended internal data memory (XRAM) for storing teletext and display data.
A 16-bit program counter and a dedicated banking logic provide the processor with its
512-Kbyte addressing capabilities (for ROM-less versions, up to 19 address lines are
available). The program counter allows the user to execute calls and branches to any
location within the program memory space. There are no instructions that permit
program execution to move from the program memory space to any of the data memory
space.
6.3.2.1 Program Memory
Certain locations in program memory are reserved for specific programs. Locations 0000
through 0002 are reserved for the initialization program. Following reset, the CPU
always begins execution at location 0000. Locations 0003 through 0051 are reserved for
the seven interrupt-request service programs as indicated in Table 7.
Table 7
Source
External Interrupt 0
Timer 0 Overflow
External Interrupt 1
Timer 1 Overflow
Serial Interface
Teletext Sync Signals
Analog Digital Converter
Address
03 (03_H)
11 (0B_H)
19 (13_H)
27 (1B_H)
35 (23_H)
43 (2B_H)
51 (33_H)
Depending on the selected type, the user can access a part of the internal/external ROM
for the application software. Please note that another part of the Program Memory is
reserved for the TTX firmware.
Table 8
Type
SDA 5250
SDA 5251
SDA 5252
SDA 5254
SDA 5255
Available User ROM Space
480 Kbyte
8 Kbyte
16 Kbyte
16 Kbyte
24 Kbyte
externally
internally
internally
internally
internally
Semiconductor Group
49
1998-04-08