P89V51RD2 Philips Semiconductors, P89V51RD2 Datasheet - Page 14

• Manufacturer Part Number: P89V51RD2
• Description: 8-bit 80C51 5 V low power 64 kB Flash microcontroller with 1 kB RAM
• Manufacturer: Philips Semiconductors

Philips Semiconductors
7. Functional description
9397 750 12964
Product data
7.1.1 Flash program memory
7.1.2 Data RAM memory
7.1.3 Expanded data RAM addressing
7.1 Memory organization
The device has separate address spaces for program and data memory.
There are two internal flash memory blocks in the device. Block 0 has 64 kbytes and
contains the user’s code. Block 1 contains the Philips-provided ISP/IAP routines and
may be enabled such that it overlays the first 8 kbytes of the user code memory.
The 64 kB Block 0 is organized as 512 sectors, each sector consists of 128 bytes.
Access to the IAP routines may be enabled by clearing the BSEL bit in the FCF
register. However, caution must be taken when dynamically changing the BSEL bit.
Since this will cause different physical memory to be mapped to the logical program
address space, the user must avoid clearing the BSEL bit when executing user code
within the address range 0000H to 1FFFH.
The data RAM has 1024 bytes of internal memory. The device can also address up to
64 kB for external data memory.
The P89V51RD2 has 1 kB of RAM. See
structure.” on page
The device has four sections of internal data memory:
Since the upper 128 bytes occupy the same addresses as the SFRs, the RAM must
be accessed indirectly. The RAM and SFRs space are physically separate even
though they have the same addresses.
Table 5:
Not bit addressable; Reset value 00H
Bit
Symbol
1. The lower 128 bytes of RAM (00H to 7FH) are directly and indirectly addressable.
2. The higher 128 bytes of RAM (80H to FFH) are indirectly addressable.
3. The special function registers (80H to FFH) are directly addressable only.
4. The expanded RAM of 768 bytes (00H to 2FFH) is indirectly addressable by the
move external instruction (MOVX) and clearing the EXTRAM bit. (See ‘Auxiliary
Register (AUXR) in
AUXR - Auxiliary register (address 8EH) bit allocation
7
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Rev. 01 — 01 March 2004
17.
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Section 6 “Special function registers” on page
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Figure 5 “Internal and external data memory
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8-bit microcontrollers with 80C51 core
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© Koninklijke Philips Electronics N.V. 2004. All rights reserved.
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