Rabbit 2000 - 3. Details on Rabbit Microprocessor Features; 3.1 Processor Registers

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Designer’s

Handbook 17

5.

The

Rabbit

BIOS

The

Dynamic

C

programming

system

for

the

Rabbit

uses

the

concept

of

a

BIOS

(basic

input

output

system).

The

BIOS

is

a

separate

program

file

that

contains

the

basic

code

needed

to

interface

with

Dynamic

C.

It

also

normally

contains

a

software

interface

to

the

user’s

particular

hardware.

Certain

drivers

in

the

Dynamic

C

libraries

require

BIOS

rou-

tines

to

perform

tasks

that

are

hardware-dependent.

When

the

user

compiles

a

program

under

Dynamic

C,

the

BIOS

is

compiled

first

as

an

integral

part

of

the

user’s

program.

A

single

general-purpose

BIOS

is

supplied

with

Dynamic

C

for

the

Rabbit.

This

BIOS

will

allow

you

to

boot

Dynamic

C

on

any

Rabbit-based

system

that

follows

the

basic

design

rules

needed

to

support

Dynamic

C.

The

BIOS

requires

either

both

a

flash

memory

and

a

32K

or

larger

RAM,

or

just

a

128K

RAM,

for

it

to

be

possible

to

compile

and

run

Dynamic

C

programs.

If

the

user

uses

a

flash

memory

from

the

list

of

flash

memories

that

are

already

supported

by

the

BIOS,

the

task

will

be

simplified.

If

the

flash

memory

chip

is

not

already

supported,

the

user

will

have

to

write

a

driver

to

perform

the

write

operation

on

the

flash

memory.

This

is

not

difficult

provided

that

a

system

with

128K

of

RAM

and

the

flash

memory

to

be

used

is

available

for

testing.

5.1

Startup

Conditions

Set

Up

By

the

BIOS

The

BIOS

sets

up

initial

values

for

the

following

registers

by

means

of

code

and

declara-

tions.

• The

four

memory

bank

control

registers

—MB0CR,

MB1CR,

MB2CR,

and

MB3CR—are

8-

bit

registers,

each

associated

with

one

quadrant

of

the

1M

memory

space.

Each

register

determines

which

memory

chip

will

be

mapped

into

its

quadrant,

how

many

wait

states

will

be

used

for

accessing

that

memory

chip,

and

whether

the

memory

chip

will

be

write

protected.

• The

STACKSEG

register

is

an

8-bit

register

that

determines

the

location

of

the

stack

seg-

ment

in

the

1M

memory.

• The

DATASEG

register

is

an

8-bit

register

that

determines

the

location

of

the

data

seg-

ment

in

the

1M

memory,

normally

the

location

of

the

data

variable

space.

• The

SEGSIZE

register

is

an

8-bit

register

holding

two

4-bit

registers.

Together

the

reg-

isters

determine

the

relative

size

of

the

root

code,

data

segment

and

stack

segment

in

the

64K

root

space.

• The

MMIDR

register

is

an

8-bit

register

that

modifies

memory

system

functions

having

to

do

with

support

for

battery-backed

memory

and

separate

instruction

and

data

space

control.

• The

XPC

register

is

used

to

address

extended

code

memory.

Normally

the

user’s

code

frequently

changes

this

register.

The

BIOS

sets

the

initial

value.

• The

SP

register

is

the

system

stack

pointer.

It

is

frequently

changed

by

the

user’s

code.

The

BIOS

sets

up

an

initial

value.

All

together

there

are

11

MMU,

MIU

registers

that

are

set

up

by

the

BIOS.

These

registers

determine

all

aspects

of

the

hardware

setup

of

the

memory.

Table of Contents

Other manuals for Rabbit 2000

User Manual230 pages

Instruction & Reference Manual174 pages

Reference Manual120 pages

Getting Started Manual54 pages

Getting Started43 pages