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St. Clement Okhridsky University of Sofia












Sofia 1990















PYLDIN 601A is a trademark of Abacus Co.

EduLAN is a trademark of ComseD.





All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic mechanical, photocopying, recording or otherwise, without the prior written permission of SOFTWARE RESEARCH & DEVELOPMENT LABORATORY. Printed in Bulgaria.




5, A. Ivanov Blvd.
1126 Sofia, Bulgaria
phone: (359 2) 70 61 58, 62 77 54
fax: (359 2) 70 62 48




1 Getting acquainted                                7

1.1 Specifications................................. 7

2 UniDOS                                            9

2.1 UniDOS files................................... 9

2.2 UniDOS commands................................ 9

2.3 UniDOS error messages.......................... 16

3 The Text Editor - UniED                           19

4 UniBIOS calls                                     21

5 Assembler Instructions                            23






The realization of the system software for the Pyldin microcomputer is a result of the hard work and the experience of the authors and the whole group participating in the Pyldin project. The aim was a creation of a comfortable and functional software environment in a respect with the computers of this class.

The style of the system software was intentionally directed to what is known as PC-DOS (and run on IBM-PC machines and compatibles). The benefits of such approach is the considerable reduce of time necessary to start over (in case of such experience). This approach was observed also in many technical decisions. One of the great advantages is the physical and logical 100 % compatibility of floppy disks of Pyldin and IBM-PC compatible machines. Thus you can read and write diskettes with Pyldin and/or with other machine. So you can say that Pyldin is file-compatible with an IBM-PC.

This book don't teaches you programming, it is a reference manual. A prior experience with computers is supposed. The book itself consists of several chapters - acquaintance with the computer, description of UniDOS commands, the UniBIOS calls, the Text Editor, the microprocessor instructions and the assembler directives.

The UniDOS commands are very similar to PC-DOS ones, with very exceptions they may be considered a subset of PC-DOS. The Text editor is similar in concept to editors like Word and Word-Perfect or the PE2. Two other products - UniPASCAL and UniBASIC are also similar to the corresponding products found for IBM-PCs.

We hope, that you will enjoy working with our software.







Chapter 1

Getting acquainted

1.1 Specifications

Technical specifications






Chapter 2


2.1 UniDOS files

2.2 UniDOS commands

The following convention is used in describing UniDOS commands:

Redirection of input and output

Input and output of commands and most of the programs may be redirected from/to file or character device. The < symbol is used for redirecting the input of a command (instead of the keyboard) and > or >> symbols are used for redirecting of the output. The >> is used for explicit appending to file (the file may be created if does not exist), otherwise the file is always created (old contents are lost).

Syntax: <command> <redirection symbol> <filename or device>

Example: DIR > PRN:



CD - Change Directory

This command is used for changing current directory. If no parameters are specified, the current directory is displayed. The symbol \ is used for the root directory and for separator between subdirectories. The symbol .. is used for the parent directory.

Syntax: CD [drive:][pathname]

Example: CD \MYFILES

Type: internal


CLS - Clear Screen

This command is used for clearing the screen. The video mode is not changed.

Syntax: CLS

Example: CLS

Type: internal


COPY - copy file(s)

This command is used for copying file(s). Wildcards * and ? are accepted. Omitted parameters are substituted with default drive and directory and the filename(s) are the same. Existing files are overwritten if the target drive/directory differs from the source. The character devices CON:, PRN:, AUX: and NUL: can be used as source (if possible) or target.

Syntax: COPY <source specification> [<destination specification>]


Type: internal

Error messages:


specifications are identical.

PATH NOT FOUND - source specification is not valid.


DATE - set current date

This command is used for setting the current date. If no parameters are given the old date is displayed and the user is asked for the new date. If no hardware clock is present the date is set to January 1-st, 1989. The format of the date specification is
dd-mmm-[yy]yy, so dates after 01-JAN-[19]80 and before 31-DEC-2099 may be entered.

Syntax: DATE [<date specification>]

Example: DATE 03-JUN-90

Type: internal


DIR - DIRectory

This command is used for displaying the contents of the specified directory. If no directory is specified contents of the current directory are displayed. Wildcards * and ? are accepted. The output may be redirected to file or printer.

Syntax: DIR [<drive:>][<path>]

Example: DIR A:*.TXT

Type: internal



This command is used for copying of diskettes. Only standard 180, 360 or 720 KB diskettes may be copied. Target diskette may be formatted if necessary. The process of copying may be quite tedious on one-floppy system.

Syntax: DISKCOPY <source_drive> <destination_drive>

Example: DISKCOPY A: B:

Type: external


DEL - DELete files

This command is used for erasing disk files. Hidden, system or read-only files are not erased. The number of erased files is displayed.

Syntax: DEL [<drive:>][<path>]<filename>

Example: DEL *.BAK

Type: internal



This command is intended for use in JOB-files. Its purpose is to echo a message on screen or to supress output during processing of a JOB file.

Syntax: ECHO [ON or OFF] or [<any combination of pritable characters>]

Example: ECHO OFF

Type: internal


FORMAT - FORMAT diskette

This command is used for initializing diskettes. Physical format is performed and new FAT (File Allocation Table) and directory are created. The following formats are supported:

If the number of tracks is not specified, the default is 40 tracks, except the case of 80-track FDD, which has to be declared with the corresponding MODE command. If the number of heads is not specified it is assumed that the FDD is double-sided.

Syntax: FORMAT <drive:> [/<number_of_tracks>] [/<number_of_heads>]

Example: FORMAT A:

Type: external



This command is used for specifing the maximum possible amount of open files in one and the same moment. The default is 15 (after bootstrap) and may be increased up to 32. Each new handle uses about 530 bytes of memory, thus reducing the amount of memory available for programs. The number of handles can be increased only, decreasing is ignored. It is recommended to include this command in the AUTOEXEC.JOB file.

Syntax: HANDLES <number_of_handles>

Example: HANDLES 24

Type: internal


MD - Make Directory

This command is used for creating new subdirectories. If the full path is not provided the directory is created as a subdirectory of the current one.

Syntax: MD [<drive:>][<path>]<directory>

Example: MD TMP

Type: internal


MODE - select MODE of operation

This command is used to select mode of operation of specific devices supported by UniDOS. The current release supports display, auxiliary channel (RS-232) and floppy disk drives.

Display mode

User can select between 80-column and 40-column text modes or to return to text mode from graphics. In case of 40-column text mode default attribute can be specified. The attribute is a positive number between 0 and 255 or $FF in hexadecimal notation which is formed by the background color (0..15) added with foreground color (0..7) multiplied by 16 and finally added with 128 for blinking if desired. If no attribute is given black and white mode is selected.

Syntax: MODE <number_of_columns> [<attribute>]

Example: MODE 40

Type: internal

Auxiliary channel mode

User can select baud rate and format of the serial interface (RS-232-C). The following baud rates are supported: 150, 300, 600, 1200, 2400, 4800, 9600, 19200. The eight possible formats (0 to 7) specify the number of data bits (7 or 8), parity control (none, odd or even) and the number of stop bits (1 or 2).


data bits

Parity control

stop bits


































Syntax: MODE <baudrate> <format>

Example: MODE 1200 4

Type: internal


Floppy Disk Drive mode

In case of using of quadro density floppy disk drives (80-track) the user must specify explicitly the type of FDD. This is necessary for proper formatting of diskettes in such drives and reading/writing of 360 KB (double density) diskettes (40-track) in such drives. In this case the FDD is automatically driven in a double step mode. The corresponding command is recommended to be included in the AUTOEXEC.JOB file.

Syntax: MODE <drive:> <number_of_tracks>

Example: MODE A: 80

Type: internal


MON - MONitor

This command is used for invoking system monitor program. The commands of the monitor program are described in the appendix. Returning to UniDOS is done by monitor Q (quit) command.

Syntax: MON

Type: internal



This command is intended for use in JOB-files. Its purpose is to provide pause, which is terminated by pressing a key on the keyboard. When executed the following message is displayed:

Press any key to continue...

User may be asked before this to change diskettes, etc.

Syntax: PAUSE

Type: internal


REM - REMark

This command is intended for improving documentation of JOB-files. Any characters on the line following REM are ignored during processing of the JOB-file.

Syntax: REM [<any text>]

Example: REM This is my comment.

Type: internal


REN - REName files

This command is used for renaming files. Wildcards are accepted, but should be used carefully. The new name must be unique.

Syntax: REN [<drive:>][<path>]<oldname> <newname>


Type: internal


RD - Remove Directory

This command is used for removing subdirectories. The directory must be empty (all files, including system, hidden and subdirectories must be removed before that). The main directory can not be deleted.

Syntax: RD [<drive:>][<path>]<directory_name>

Example: RD TEMP

Type: internal


TIME - set current time

This command is used for setting current time. If no clock card is present the time is set to 0:00:00 after power on. Time must be specified in 24 hour format i.e. 0:00:00 to 23:59:59 are valid entries.

Syntax: TIME [<time specification>]

Example: TIME

Type: internal


TYPE - display contents of a text file

This command is used for used for displaying contents of text files. Wildcards are NOT accepted. If the length of text lines exceeds the screen width the line is splitted at the corresponding position i.e. at the 40-th column. The process is terminated upon physical end of the file or coming upon EOF character - CTRL-Z. The rest of the file (till the physical end) is skipped.

Syntax: TYPE [<drive:>][<path>]<filename>


Type: internal


VER - VERsion of UniDOS

This command is used for displaying the version of UniDOS loaded. The logo of UniDOS is displayed.

Syntax: VER

Type: internal


2.3 UniDOS error messages


Access denied (Запрещен доступ)
Появляется когда атрибуты файла не позволяют доступ к нему.

Address failure (Ошибка в адресном поле диска)
Появляется когда поврежден диск.

Attempt to remove the current directory (Сделана попытка уничтожить текущую директорию)

AUX: framing (Хардверная ошибка серийного интерфейса)

AUX: overrun (Перекрытие байтов, идущих по серийному интерфейсу)

AUX: parity (Контроль по четности - неудовлетворителен)

AUX: timeout (До конца контрольного времени обмен не реализован)

Bad command or file name (Неверная команда или неправильно введенное имя файла)

Cannot execute .CMD file (Невозможно выполнить .CMD файла)
Самый обычный вариант появления - когда уже стартирован .CMD файл.

Data failure (Ошибка в поле данных при обращении к диску)
Появляется когда поврежден диск.

Directory exists (Уже существует такая директория)

Directory not empty (Не пустая директория)

Disk full (Диск заполнен до конца)

Disk write protected (Диск защищен от записи)

Failure in .PGM file (Ошибка при стартирование .PGM файла)
Появляется при повреждении .PGM файла.

FAT failure (Ошибка в FAT-е - в таблице описаний файлов)

File already open (Попытка открытия открытого файла)

File cannot be copied onto itself (Файл невозможно копировать на себя)

File creation failure (Ошибка при создании файла)

File exists (Файл существует)

File opening failure (Ошибка при открытии файла)

File not found (Файл не найден)

General failure (Невозможно обращение к диску)
Вероятно диск не форматирован или получилась хардверная ошибка.


Insufficient memory (Не хватает памяти)

Invalid date (Невалидная дата)
Неверная формат введенной даты.

Invalid drive (Неправильно задан идентификатор дисковода)

Invalid media type (Неправильной тип формата дискеты)

Invalid name (Неправильное имя)

Invalid number of parameters (Неправильное число параметров)

Invalid parameter (Неправильный параметр)

Invalid sector (Неправильный сектор)

Invalid time (Неправильно заданное время)

Not disk file (Это - не дисковый файл)
Вероятно использовали неправильно резервированное имя.

Not same device (Не то устройство)
Проверьте синтаксис команды.

Path not found (Нет такого пути)
Проверьте, правильно ли набрано имя.

Printer general failure (Невозможно обращение к принтеру)
Вероятно принтер не включен.

Printer out of paper (Кончилась бумага в принтере)

Printer timeout (Ошибка при обращения к принтеру)

Root directory full (Главная директория заполнена до конца)

Too many open files (Число открытых файлов больше допустимого)
Вероятно сделана попытка открыть файл когда уже открыты столько файлов, сколько указано в команде HANDLES.







Chapter 3

The Text Editor - UniED






Chapter 4

UniBIOS calls







Chapter 5

Assembler Instructions



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