Table of Contents
Advertisement
MB96300 Super Series Hardware Manual
12.2.6
External Area Select register (EAS[5:2])
The external bus interface supports two types of External address areas:
- Areas with fixed address range (External areas 0 and 1)
- Areas with selectable address range (External areas 2 to 5)
■ Overview
The external bus interface supports two types of address areas:
• Fixed address range (External areas 0 and 1):
- External area 0 is fixed to address range 00.00f0
- External area 1 is fixed to address range 00.0c00
The RAM-Start depends on device configuration and may be different for various devices of the same
series. It cannot be changed by the Software.
The RAM-Start address on EVA-Devices can be configured and depends on the emulated device.
• Programmable address range (External areas 2 to 5):
- The External Address Select register EAS for each area defines the upper 8 address bits of the
corresponding external area, allowing addresses within 64 KB to be specified.
- The EASZ[2:0] bits of the corresponding External Area Configuration register EACH[5:2] define how
many bits of the EAS register are used for the address comparison. Hence External areas from 64
KByte to 8 MByte can be selected.
- The address area below 10:0000
■ External Area Select Register EAS[5:2]
External area select register EAS[5:2]
address: EAS2: 0006EC
EAS3: 0006ED
EAS4: 0006EE
EAS5: 0006EF
These registers are used to set the address decode area for the External areas 2-5. They specify the upper 8
bits of the address value, allowing an address within 64kB to be specified.
Disable the corresponding External area in the External Bus Mode register (EBM) when changing the EAS
register to avoid malfunction.
■ Initial values of EAS[5:2]
The EAS[5:2] registers have different initial values. The initial values divide the memory area above address
H
Figure 12.2-10 External Area Select registers (EAS[5:2])
15/7
14/6
13/5
H
H
A7
A6
A5
H
H
R/W
R/W
R/W
CHAPTER 12 EXTERNAL BUS INTERFACE
...00.00ff
.
H
H
...RAM-Start.
H
however cannot be selected.
12/4
11/3
10/2
A4
A2
A3
R/W
R/W
R/W
9/1
8/0
EAS[5:2]
Initial value
A1
A0
********
R/W
R/W
319
Advertisement
Table of Contents
