IBM 600 Calling Convention, Parameter Structure, Uses Stack/data area Directly With Selector When

Calling Convention

The

client

can

invoke the SMAPI BIOS with a far-call to the entry

point

that

is

specified

in

the

header

file. All

parameters

for

the

BIOS

and

other

results are stored in

the

client data

area;

the client

needs

to prepare

an

input parameter and output parameter area in

its

data

area, and informs this area by pushing

those pointers

onto

its stack

before the far-calls.

The

SMAPI

BIOS

uses

the

stack/data area

directly

with

the

selector

when

the

BIOS

is

invoked. Therefore,

the

caller needs

to

define

the

same

privilege

level as

the

BIOS.

Parameter Structure

The	memory			allocation for	the input/output field should be prepared
by the caller. The input					field	specifies		the function	request to the
SMAPI BIOS, and the BIOS					fills	in the return value to			the output
field.
Input	Field
Field					Offset		Length
					(in Hex)
Major		Function		Number	00		Byte
Minor		Function		Number	01		Byte
Parameter			1		02		Word
Parameter			2		04		Word
Parameter			3		06		Word
Parameter			4		08		Double	word
Parameter			5		0C		Double	word

B-6 SMAPI BIOS