HD6432621 Hitachi, HD6432621 Datasheet - Page 179

• Manufacturer Part Number: HD6432621
• Description: (HD64F262x Series) 16-Bit Microcomputer
• Manufacturer: Hitachi

7.1
The H8S/2626 Series and H8S/2623 Series have an on-chip bus controller (BSC) that manages the
external address space divided into eight areas. The bus specifications, such as bus width and
number of access states, can be set independently for each area, enabling multiple memories to be
connected easily.
The bus controller also has a bus arbitration function, and controls the operation of the internal bus
masters: the CPU and data transfer controller (DTC).
7.1.1
The features of the bus controller are listed below.
Manages external address space in area units
Basic bus interface
Burst ROM interface
Idle cycle insertion
Write buffer functions
Bus arbitration function
Manages the external space as 8 areas of 2 Mbytes
Bus specifications can be set independently for each area
Burst ROM interface can be set
8-bit access or 16-bit access can be selected for each area
2-state access or 3-state access can be selected for each area
Program wait states can be inserted for each area
Burst ROM interface can be set for area 0
Choice of 1- or 2-state burst access
An idle cycle can be inserted in case of an external read cycle between different areas
An idle cycle can be inserted in case of an external write cycle immediately after an
External write cycle and internal access can be executed in parallel
Includes a bus arbiter that arbitrates bus mastership among the CPU and DTC
external read cycle
Overview
Features
Section 7 Bus Controller
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