HD6433044 Datasheet, PDF (562/867 Pages) Hitachi Semiconductor – Hitachi Single-Chip Microcomputer

Section 17 RAM
17.1 Overview
The H8/3048 and H8/3047 have 4 kbytes of high-speed static RAM on-chip. The H8/3045 and
H8/3044 have 2 kbytes. The RAM is connected to the CPU by a 16-bit data bus. The CPU
accesses both byte data and word data in two states, making the RAM useful for rapid data
transfer.
The on-chip RAM of the H8/3048 and H8/3047 is assigned to addresses H'FEF10 to H'FFF0F in
modes 1, 2, 5, and 7, and to addresses H'FFEF10 to H'FFFF0F in modes 3, 4, and 6. The on-chip
RAM of the H8/3045 and H8/3044 are assigned to addresses H'FF710 to H'FFF0F in modes 1, 2,
5, and 7, and to addresses H'FFF710 to H'FFFF0F in modes 3, 4, and 6. The RAM enable bit
(RAME) in the system control register (SYSCR) can enable or disable the on-chip RAM.
17.1.1 Block Diagram
Figure 17-1 shows a block diagram of the on-chip RAM.
On-chip data bus (upper 8 bits)
On-chip data bus (lower 8 bits)
Bus interface
SYSCR
H'FEF10*
H'FEF12*
H'FEF11*
H'FEF13*
On-chip RAM
H'FFF0E*
H'FFF0F*
Even addresses
Legend
SYSCR: System control register
Odd addresses
Note: * This example is of the H8/3048 operating in mode 7. The lower 20 bits of the address
are shown.
Figure 17-1 RAM Block Diagram
553