![](http://datasheet.mmic.net.cn/90000/M32000D4BFP-80_datasheet_3496147/M32000D4BFP-80_7.png)
SINGLE-CHIP 32-BIT CMOS MICROCOMPUTER
MITSUBISHI MICROCOMPUTERS
M32000D4BFP-80
7
PIN DESCRIPTION (2/3)
type
pin name
name
I/O
function
bus
SID
space
output
Space identifier between user space and I/O space.
control
identifier
(Hi-Z)*
SID = "L": user space
SID = "H": I/O space
SID = undefined: when idle
____
BCH, BCL
byte control
I/O
Indicates the valid byte positions of transferred data.
(Hi-Z)*
____
BCH corresponds to the MSB side (D0 to D7), and BCL corresponds
____
to the LSB side (D8 to D15). During a read bus cycle, both BCH
____
and BCL are an "L" level.
____
During a write bus cycle, either BCH and/or BCL is an "L" level
depending on the byte(s) to be written.
When accessing the internal DRAM from an external bus master,
the byte control signal is input from the system bus side.
__
BS
bus start
output
__
When the M32000D4BFP-80 drives an external bus cycle, BS
goes to an "L" level at the start of the bus cycle.
__
In burst transfer, BS goes to the "L" level for each transfer
cycle. When accessing internal resources such as an internal
__
DRAM or internal I/O register, BS is not output.
ST
bus status
output
Indicates whether the bus cycle that the M32000D4BFP-80 drives
is an instruction fetch access cycle or an operand access cycle.
ST = "L": for instruction fetch access
ST = "H": for operand access
ST = undefined: when idle
__
R/W
read/write
I/O
__
Outputs R/W to identify whether the external bus cycle a read or
a write cycle. When accessing the internal DRAM from an external
__
bus master, R/W is input from the external bus.
______
BURST
burst
output
The M32000D4BFP-80 drives two consecutive bus cycles to access
32-bit data allocated on the 32-bit word boundary.
For instruction fetches, it drives 8 (max.) consecutive cycles
(8 cycles in instruction cache mode) to data on the 128-bit boundary.
______
During these consecutive bus cycles, BURST goes to "L" level.
When accessing 32-bit data, an "L" level followed by an "H" level
is output from address A30, because the MSB-side 16 bits are
accessed prior to the LSB-side 16 bits.
When accessing 128-bit data, the addresses are output from an
arbitrary 16-bit aligned address and wraparound within a 128-bit
aligned boundary.
* (Hi-Z): This pin goes to high-impedance in the hold state.
(Hi-Z)*