SM8521 Datasheet, PDF (14/56 Pages) Sharp Electrionic Components – 8-Bit Single-Chip Microcomputer

SM8521
Data Format
The SM85CPU supports four data types : bit, 4-bit
BCD, byte, and word data.
REGISTER FILE DATA FORMATS
The register file (0000H-007FH) and RAM (0080H-
00FFH) accessible with register file R and register
file pair RR addressing support processing for all 4
data types : bit, 4-bit BCD, byte, and word data.
Fig. 3 shows the data layout in the register file.
• Bit data (register file)
Bit manipulation instructions access bit data in the
register by register file R addressing, which gives
the byte address in the register file (0000H-007FH),
or RAM (0080H-00FFH), and the operand b, which
gives the bit number within the byte.
• Byte data (register file)
Instructions access the byte data in the register file
by register file R addressing, which gives the byte
data address in the register file (0000H-007FH) or
RAM (0080H-00FFH).
• Word data (register file)
Instructions access word data in the register file by
register file pair RR addressing, which gives the word
address, even and 2 bytes address, in the register
file (0000H-007FH) or RAM (0080H-00FFH). The
address must be even (0, 2, 4,…, 254). Specifying an
odd address leads to unreliable results.
• BCD data (register file)
The decimal adjust instruction (DA), used to adjust
BCD digits after an odd or subtraction, accesses a
BCD data byte in the register file by register file R
addressing.
• Notice for the general register on register file
The general registers are the first 16 bytes (0000H-
000FH) in the register file. They can be accessed
as byte-sized by register file R addressing and as
word-sized by register file pair RR addressing.
MEMORY DATA FORMATS
The memory area (ROM and RAM 0000H-FFFFH)
supports processing for all 4 data types : bit, 4-bit
BCD, byte and word data. However, bit data is
limited to the ranges (0000H-00FFH, FF00H-FFFFH),
and 4-bit BCD data to the ranges 0000H-00FFH.
Fig. 3 shows the data layout in memory.
• Bit data (memory)
Bit manipulation instructions access bit data in
memory by register index n(r) addressing, which
gives the byte address in the range (0000H-00FFH),
or by direct special page DAp addressing, which
gives the byte address in the range (FF00H-FFFFH),
and the operand b, which gives the bit number
within the byte.
• Byte data (memory)
Instructions access the byte data in memory by
shorthand (0000H-00FFH or FF00H-FFFFH) or full
(0000H-FFFFH) address.
• Word data (memory)
Instructions access the word data, continue 2
bytes, in memory by shorthand (0000H-00FFH or
FF00H-FFFFH) or full (0000H-FFFFH) address.
Unlike word data in the register file, the address
can be even or odd.
• BCD data (memory)
The decimal adjust instruction (DA), used to adjust
BCD digits after an odd or subtraction, accesses a
BCD data byte in memory by register index @r
addressing.
• Notice for general register on memory
The general registers are actually in a RAM area
specified by register pointer RP, so they can be
read and modify directly as RAM. While
programming, the programmer must take care to
arrange program data so that other RAM
operations do not destroy general registers content.
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