HD64570 HITACHI [Hitachi Semiconductor], HD64570 Datasheet - Page 68

• Manufacturer Part Number: HD64570
• Description: Serial Communications Adaptor
• Manufacturer: HITACHI [Hitachi Semiconductor]

Table 2.7
Symbol
BUSY
CPU0,
CPU1
Note: Do not change the mode when the SCA is turned on.
Rev. 0, 07/98, page 52 of 453
CP-84
80
74, 73
System Control Lines (cont)
Pin Number
FP-88
7
88, 87
Input/
Output
Input/
output
(Open
drain)
Input
Description
Bus busy: indicates that the bus is in use.
Slave mode
Master mode
Note: Be sure to pull this line up to V
MPU select: Select the bus interface mode.
CPU1
0
1
0
1
CPU0
0
0
1
1
Input line. An external device
drives BUSY active low to
indicate that it is using the bus.
When the SCA requests the
bus after the HOLDA or
BUSACK input becomes
active, if BUSY is low (active),
the SCA waits until BUSY goes
high (inactive) before taking
control of the bus.
The SCA drives this line active
low as long as it holds the bus.
When it finishes using the bus,
the SCA drives this line high
(inactive) and releases the bus
after which this line becomes
an input line.
CPU Mode
Mode 0 (8086-system 16-bit
MPU mode)
Mode 1 (64180 mode)
Mode 2 (68000-system 16-bit
MPU mode I)
Mode 3 (68000-system 16-bit
MPU mode II)
CC
.