MC146805E2CFN INNOVASIC [InnovASIC, Inc], MC146805E2CFN Datasheet - Page 6

• Manufacturer Part Number: MC146805E2CFN
• Description: Microprocessor Unit
• Manufacturer: INNOVASIC [InnovASIC, Inc]

IA6805E2
Microprocessor Unit
Functional Description
Memory:
Copyright
innovASIC
ACCESS VIA
INTERRUPT
ADDRESS
VECTORS
PAGE 0
DIRECT
The MPU is capable of addressing 8192 bytes of memory and I/O registers. The locations
are divided into internal memory space and external memory space as shown in Figure 5.
The first 128 bytes of memory contain internal port I/O locations, timer locations, and 112
bytes of RAM. The MPU can read from or write to any of these locations. During program
reads from on chip locations, the MPU accepts data only from the addressed on chip
location. Any read data appearing on the input bus is ignored. The shared stack area is used
during interrupts or subroutine calls. A maximum of 64 bytes of RAM is available for stack
usage. The stack pointer is set to $7f at power up. The unused bytes of the stack can be used
for data storage or temporary work locations, but care must be taken to prevent it from
being overwritten due to stacking from an interrupt or subroutine call.
2002
The End of Obsolescence
8191
127
128
255
256
0
TIMER INTERRUPT FROM WAIT STATE ONLY
EXTERNAL INTERRUPT
EXTERNAL MEMORY
SPACE (8064 BYTES)
TIMER INTERRUPT
TIMER RAM
I/O PORTS
RESET
SWI
Figure 5. Memory Map
ENG21108140100
$0000
$007F
$0080
$00FF
$0100
$1FF6 - $1FF7
$1FF8 - $1FF9
$1FFA - $1FFB
$1FFC - $1FFD
$1FFE - $1FFF
Page 6 of 31
127
10
15
16
3
0
1
2
4
5
6
9
63
64
7
8
PORT A DATA DIRECTION REGISTER
PORT B DATA DIRECTION REGISTER
As of Production Version 00
EXTERNAL MEMORY SPACE
EXTERNAL MEMORY SPACE
EXTERNAL MEMORY SPACE
EXTERNAL MEMORY SPACE
EXTERNAL MEMORY SPACE
TIMER CONTROL REGISTER
PORT A DATA REGISTER
PORT B DATA REGISTER
TIMER DATA REGISTER
(112 BYTES)
RAM
(64 BYTES MAX)
Data Sheet
STACK
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