Initial Register Values; Data Formats - Renesas F-ZTAT H8 Series Hardware Manual

8-bit single-chip microcomputer

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Initial Register Values

When the CPU is reset, the program counter (PC) is initialized to the value stored at address

H'0000 in the vector table, and the I bit in the CCR is set to 1. The other CCR bits and the general

registers are not initialized. In particular, the stack pointer (R7) is not initialized. To prevent

program crashes the stack pointer should be initialized by software, by the first instruction

executed after a reset.

The H8/300L CPU can process 1-bit data, 4-bit (BCD) data, 8-bit (byte) data, and 16-bit (word)

• Bit manipulation instructions operate on 1-bit data specified as bit n in a byte operand

(n = 0, 1, 2, ..., 7).

• All arithmetic and logic instructions except ADDS and SUBS can operate on byte data.

• The MOV.W, ADD.W, SUB.W, CMP.W, ADDS, SUBS, MULXU (8 bits × 8 bits), and

DIVXU (16 bits ÷ 8 bits) instructions operate on word data.

• The DAA and DAS instructions perform decimal arithmetic adjustments on byte data in

packed BCD form. Each nibble of the byte is treated as a decimal digit.

Rev.3.00 Jul. 19, 2007 page 31 of 532

REJ09B0397-0300