HD404019R Datasheet, PDF (48/65 Pages) Renesas Technology Corp – CMOS 4-bit single-chip microcomputers

HD404019R Series
Direct Addressing Mode: The program can branch to any address in ROM memory space by executing
the JMPL, BRL, or CALL instruction. These instructions replace the 14 program counter bits (PC₁₃ to PC₀)
with 14-bit immediate data.
Current Page Addressing Mode: The MCU has 8 pages of ROM with 256 words per page. By executing
the BR instruction, the program can branch to an address on the current page. This instruction replaces the
low-order eight bits of the program counter (PC₇ to PC₀) with 8-bit immediate data.
When the BR instruction is on a page boundary (256n + 255) (figure 24), executing it transfers the PC
contents to the next page, due to the hardware architecture. Consequently, the program branches to the next
page when the BR instruction is used on a page boundary. The HMCS400-series cross macroassembler has
an automatic paging facility for ROM pages.
Zero-Page Addressing Mode: By executing the CAL instruction, the program can branch to the zero-page
subroutine area, which is located at $0000 to $003F. When the CAL instruction is executed, 6 bits of
immediate data are placed in the low-order six bits of the program counter (PC₅ to PC₀) and 0s are placed in
the high-order eight bits (PC₁₃ to PC₆).
Table Data Addressing Mode: By executing the TBR instruction, the program can branch to the address
determined by the contents of the 4-bit immediate data, accumulator, and B register.
P Instruction: ROM data addressed by table data addressing can be referenced by the P instruction (figure
25). When bit 8 in the referred ROM data is 1, 8 bits of ROM data are written into the accumulator and B
register. When bit 9 is 1, 8 bits of ROM data are written into the R1 and R2 port output registers. When
both bits 8 and 9 are 1, ROM data are written into the accumulator and B register, and also to the R1 and
R2 port output registers at the same time.
The P instruction has no effect on the program counter.
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