Section 2 CPU
Rev. 7.00 Mar 10, 2005 page 29 of 652
REJ09B0042-0700
Refer to the H8/300L Series Programming Manual for the action of each instruction on the flag
bits.
2.2.3 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. The stack pointer
should be initialized by software, by the first instruction executed after a reset.
2.3 Data Formats
The H8/300L CPU can process 1-bit data, 4-bit (BCD) data, 8-bit (byte) data, and 16-bit (word)
data.
• 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.
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