IA6805E2

Data Sheet

Microprocessor Unit

As of Production Version 00

Copyright

© 2002

ENG21108140100

www.innovasic.com

Customer Support:



The End of Obsolescence

™

Page 6 of 31

1-888-824-4184

Functional Description

Memory:

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.

RAM

(112 BYTES)

I/O PORTS

TIMER RAM

EXTERNAL MEMORY

SPACE (8064 BYTES)

TIMER INTERRUPT FROM WAIT STATE ONLY

TIMER INTERRUPT

EXTERNAL INTERRUPT

SWI

RESET

PORT A DATA REGISTER

PORT B DATA REGISTER

EXTERNAL MEMORY SPACE

EXTERNAL MEMORY SPACE

PORT A DATA DIRECTION REGISTER

PORT B DATA DIRECTION REGISTER

EXTERNAL MEMORY SPACE

EXTERNAL MEMORY SPACE

TIMER DATA REGISTER

TIMER CONTROL REGISTER

EXTERNAL MEMORY SPACE

$1FF6 - $1FF7

$1FF8 - $1FF9

$1FFA - $1FFB

$1FFC - $1FFD

$1FFE - $1FFF

$0000

$007F

$0080

$00FF

$0100

63

64

127

0

127

128

255

256

8191

INTERRUPT

VECTORS

ACCESS VIA

PAGE 0

DIRECT

ADDRESS

STACK

(64 BYTES MAX)

0

1

2

3

4

5

6

7

8

9

10

15

16

Figure 5. Memory Map