Tandy 600 User manual

TANDY

Reference D

CUSTOM MANUFACTURED FOR RADIO SHACK, ADIVISION OF TANDY CORPORATION

16 Bit Hand-Held Operating System

Programmers Reference Guide

Licensed to Tandy Corporation

BIOS and BIOS Specification

Licensed to Tandy Corporation

All portions of this software are copyrighted and are the

proprietary and trade secret information of Tandy Corpora-

tion and/or its licensor. Use, reproduction or publication of

any portion of this material without the prior written authori-

zation by Tandy Corporation is strictly prohibited.

Tandy 600

Programmers Reference Guide

BIOS and BIOS Specification

Reproduction or use, without the express written permission

from Tandy Corporation and/or its licensor, of any portion of

this manual is prohibited. While reasonable efforts have

been taken in the preparation of this manual to assure its

accuracy, Tandy Corporation assumes no liability resulting

from any errors or omissions in this manual, or from the use

of the information contained herein,

Tandy is aregistered trademark of Tandy Corporation.

10987654321

TANDY 600

PROGRAMMERS REFERENCE

BIOS AND BIOS SPECIFICATION

GUIDE

Table of Contents

Page

Section 1—Programmers Reference 1

Interrupt Vectors used by HH O/S 1

Descriptions of Interrupts 2

Error Codes 10

HH O/S Function Calls 11

HH O/S Database Function Calls 76

Applications Programs Under HH O/S 111

Device Drivers Under HH O/S 117

Section 2—BIOS Specification 123

Appendices:

A-Summation of O/S Functions 185

B-Changing Main Menu Labels 191

C-Program Transfer and Conversion 195

D-MS-WORKS Utilities for Development 197

Section 1

PROGRAMMERS

REFERENCE

Interrupt Vectors Used by HH O/S

The following interrupts are used by HH O/S:

INT No. Function

40h Reserved

41 h Reserved

42h HH O/S Function Call

43h DBMS Function Call

44h Free AMI File Space

45h File System Moving

46h Get File Address

47h Translate Address

48h Reserved

49h Reserved

4Ah Reserved

4Bh Reserved

4Ch RS-232C Receiver Hook

4Dh Interval Timer Hook

4Eh Power Low/Off Hook

4Fh Keyboard Queue Hook

Descriptions of Interrupts

INT42h Function Cal

SP:

BP:

SI:

Dl:

XXXXXXXX Entry; AH -Function Code

Other registers are function specific

Exit Function specific

IP:

FLG

See the section on Function Calls for descriptions of the available functions and their entry

and exit parameters.

INT 43h -DB Function Call

XXXXXXXX XXXXXXXX

SP:

BP:

SI:

Dl:

IP:

FLG

Entry: AH -Function Code

DS:DX -Parameter Block

Exit AX -Return value or error code

See the section on DBMS Function Calls for descriptions of the available functions and their

entry and exit parameters.

INT 44h -Free AMI File Space

SP:

BP:

SI:

Dl:

IP:

FLG

XXXXXXXX XXXXXXXX

Entry: CX -Number paragraphs of memory

needed

Exit: AX -Number of paragraphs of memory

released

This hook is provided as amechanism for the HH O/S to request that an application program

release memory space from its AMI. Whenever amemory request has occurred during the

execution of an O/S function call, and there is not sufficient free memory to satisfy the

request, HH O/S will invoke this interrupt with parameters specifying the amount of additional

memory required to satisfy the memory request. The application program may then free up

memory in its AMI file if possible, and return to HH O/S informing it of how much memory may

be recovered from the AMI file.

Some programs may run more efficiently if they can initially allocate alarge block of memory

to their AMI, and then incrementally release it back to the system as required. This hook is

provided to support such applications. It is never necessary for an application program to use

this hook vector.

On entry, CX will specify the number of paragraphs of memory that the O/S requires to

complete the current memory request. The segment registers DS and ES will contain the

same value as on the original entry to the O/S function being executed. The stack registers

SS and SP will point to the stack that was in effect on entry to the O/S function.

If the application program is able to release any memory from its AMI file, it should do so. The

space freed will always be taken from the end of the file, so that any internal data structures

necessary should be moved down to place the free memory at the end of the file. The

application program should then return to the O/S by doing an IRET instruction and return in

AX the number of paragraphs of memory actually made available to the O/S to recover from

the end of the AMI file. If no memory was made available, AX must contain 0.

Any changes to DS, ES, SS, or SP within this hook routine will be remembered by the O/S

and those changed registers will be restored before returning to the application when the O/S

function call completes. If, for example, the application program's stack were at the end of the

AMI, the hook routine could copy the data on the stack down by the requested amount, adjust

SP to point to the new stack location, and then perform the IRET. HH O/S would then

remember the new location of the application program's stack, and that stack would be in

effect when the interrupted function call completes.

HH O/S will have pushed some critical information onto the application program's stack before

performing the INT 44h instruction. For this reason, the hook routine must preserve the

contents of the stack, although it is allowed to move its location.

HH O/S is not reentrant. For this reason, the INT 44h hook routine may not make any HH O/S

function calls. The INT 44h hook routine is allowed to perform any of the HH O/S interrupts

that are explicitly listed as being reentrant.

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