NXP Semiconductors
P89V51RB2/RC2/RD2
8-bit microcontrollers with 80C51 core
6. Functional description
6.1 Special function registers
Remark: SFR accesses are restricted in the following ways:
• User must not attempt to access any SFR locations not defined.
• Accesses to any defined SFR locations must be strictly for the functions for the SFRs.
• SFR bits labeled ‘-’, ‘0’ or ‘1’ can only be written and read as follows:
– ‘-’ Unless otherwise specified, must be written with ‘0’, but can return any value
when read (even if it was written with ‘0’). It is a reserved bit and may be used in
future derivatives.
– ‘0’ must be written with ‘0’, and will return a ‘0’ when read.
– ‘1’ must be written with ‘1’, and will return a ‘1’ when read.
P89V51RB2_RC2_RD2_5
Product data sheet
Rev. 05 — 12 November 2009
© NXP B.V. 2009. All rights reserved.
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