Announcement Letter Number 283-389 dated November 1, 1983
US - Last Revised on November 1, 1983

Brief Description of Announcement, Charges, and Availability

Customer Letter Section

       IBM Personal Computer Disk Operating System Version 2.1 is
announced and available. DOS 2.1 operates with all members of the
IBM Personal Computer family.
           Feature #4120
.  Replaces DOS 2.0.
.  Same function as DOS 2.0 and requires same storage.
.  Supports the IBM Personal Computer, the IBM Personal Computer
   XT, and the IBM PCjr.
.  Supports one or more diskette drives or fixed disks.
   Formatted capacity is 180KB for single-sided diskettes, 360KB
   for dual-sided diskettes.
.  Fixed disk initialization program for fixed disk support.
.  DOS can be started from diskette or fixed disk.
.  File space allocated dynamically as data is added.
.  Backup and restore commands to support fixed disk.
.  Tree-structured directories.
.  Command to display the directory structure.
.  Commands to create and remove subdirectories.
.  Sequential and direct access of data files.
.  File recovery utility.
.  Current date and time used in directory entries.
.  Supports job stream sequence of programs as batch files.
   Conditional (IF-THEN-ELSE) logic supported.
.  Automatic execution of program or job stream when system is
   turned on.
.  Graphics screen dump to printer.
.  Global file name characters for file name searches.
.  Multiple disk I/O memory buffers for improved performance.
.  Accepts commands entered in upper or lower case.
.  DOS can be copied to formatted diskettes or to fixed disks.
.  Line editor, debug, disk format, disk check, diskette copy,
   and diskette compare programs.
.  Linker for language compilers.
.  User-installable device drivers may be added for new hardware
.  Optional verify after write.
.  Extended screen and keyboard controls.
.  Redirected I/O (example: keyboard input and direct output to a
.  Piping:  output from program A used as input to program B.
.  Divert parallel printer output to asynchronous communications
   adapter (example: attach a serial printer).
.  Background file print utility permits simultaneous file
   printing with other activity.
.  Extended device error trapping.
       The IBM Personal Computer Disk Operating System Version
2.1 provides the support required for the IBM Personal Computer
hardware and an application program. It operates on the IBM
Personal Computer, the IBM Personal Computer XT, and the IBM
PCjr, and supports one or more 5-1/4" diskette drives, single- or
dual-sided, and one or two fixed disks.
       DOS provides an input/output interface for programs
written for the BASIC Interpreter or any high-level compiler
language supported by DOS on the IBM Personal Computer family.
       DOS 2.1 replaces DOS 2.0. DOS 2.1 contains the same
function as DOS 2.0 and requires the same amount of storage;
however, DOS 2.1 is the only operating system supported by IBM
for the IBM PCjr.
       In addition, DOS 2.1 provides the ability to display a
diskette directory and rename, erase, display, compare, or copy
files. DOS also permits "chaining" a series of programs in a
predefined job stream. A job stream or a single program may be
designated for automatic execution when the system is turned on.
DOS provides line editor and debug utility programs to aid in
program development. A linker program is provided to convert
language compiler relocatable modules to executable load modules.
       IBM Personal Computer DOS Version 2.1 is resident on two
diskettes. These diskettes also contain BASIC Interpreter
extensions for Disk BASIC and Advanced BASIC, as well as sample
programs that demonstrate BASIC and hardware features.
       DOS 2.1 is described in the following publications, which
are part of the DOS 2.1 package:
.  IBM Personal Computer Disk Operating System User's Guide
   (Level 2.1)
.  IBM Personal Computer Disk Operating System Reference (Level
.  IBM Personal Computer Disk Operating System Technical
   Reference (Level 2.1) (must be purchased separately - feature
   # 4125)
       The DOS manuals are required as a companion to any of the
language compiler publications.
       Planned Availability Date: First quarter 1984
       Technical Information
       Specified Operating Environment
       Hardware Requirements: IBM Personal Computer DOS 2.1 is
designed to operate with a member of the IBM Personal Computer
family with a minimum of one diskette drive and 64KB of memory. A
minimum of 128KB is recommended for the IBM PCjr, and for the IBM
Personal Computer or Personal Computer XT if a fixed disk is
       Software Requirements: Because of program requirements,
some applications may need more than the minimum 64KB. DOS is
loaded into memory from a diskette in drive A or from the fixed
disk each time the computer is turned on or "reset" is invoked.
This diskette may be the original DOS diskette, a copy of the DOS
diskette, or any diskette to which DOS has been transferred.
       DOS 2.0: DOS 2.1 has the same function and memory
requirements as DOS 2.0.  The DOS 2.0 manual has been divided
into three manuals. Two manuals (User's Guide and Reference) are
included with DOS 2.1. The third manual (Technical Reference) is
a separately purchased item. The information contained in the
Technical Reference was contained in the DOS 2.0 manual.
       DOS 1.1: DOS Version 2.1 offers function not available in
DOS 1.1 and has a higher user memory requirement. (DOS 2.1 is
approximately 12KB larger than DOS 1.1.) Where standard
(documented) programming protocols have been observed, most DOS
1.1 programs should run under Version 2.1 without change.
Examples of non-standard protocols are access of absolute memory
locations in which DOS resides and direct calls to the basic
input/output system (BIOS) for file operations. Because DOS 2.1
uses more memory, some programs may no longer fit in the same
size machines. The program will still require the same amount of
user memory, but with DOS 2.1 taking more memory, the amount
remaining for the program will be less. In this case, a program
may have to be divided into smaller segments, or more memory may
have to be added to the system.
       Technical Data
                                       DOS Command
Function                               or Utility
Configuration file                     BREAK=ON/OFF
(CONFIG. SYS)                          BUFFERS=
Substitute diskette drive              ASSIGN
Batch file support                     .BAT
Check for ctrl/break interrupt         BREAK
Check diskette or fixed disk           CHKDSK
Clear screen                           CLS
Compare files                          COMP
Copy files                             COPY
Set date                               DATE
Set time                               TIME
Delete files                           DEL, ERASE
List directory                         DIR
Compare diskettes                      DISKCOMP
Copy diskette                          DISKCOPY
Format diskette or fixed disk          FORMAT
Graphics screen dump                   GRAPHICS
Set display or printer options         MODE
Remark within batch file,              PAUSE
then wait
Print files in "background"            PRINT
Change DOS prompt                      PROMPT
Recover file                           RECOVER
Remark from batch file                 REM
Rename a file                          RENAME, REN
Transfer DOS to another                SYS
diskette or fixed disk
Set time of day                        TIME
Display file contents                  TYPE
Display DOS version                    VER
Write-verify data to                   VERIFY

Display disk or diskette               VOL
Line editor                            EDLIN
Load, alter, display/                  DEBUG
execute files
Link edit a compiled program           LINK
Change directory                       CHDIR
Substitute screen                      CTTY
and keyboard
Convert .EXE files to                  EXE2BIN
.COM format
Search for string in file              FIND
Create a subdirectory                  MKDIR
Pause after displaying                 MORE
Specify directory paths                PATH
Remove directory                       RMDIR
Set environment                        SET
Sort data                              SORT
Display directory paths                TREE
Initialize a fixed disk,               FDISK
backup fixed disk files                BACKUP
to diskette, restore files             RESTORE
from diskette to fixed disk
       IBM Personal Computer DOS is a prerequisite for the Disk
and Advanced versions of BASIC and provides I/O for the other
DOS-supported languages and application programs created by them.
       Planning Information
       Customer Responsibilities: The customer is responsible for
producing a backup copy of the original DOS diskette and for
copying DOS on the other diskettes or fixed disks as required.
All newly purchased diskettes must be initialized using the DOS
FORMAT utility.  Fixed disks must be initialized with both the
FDISK and FORMAT utilities.
       Installability: IBM Personal Computer DOS 2.1 resides on
the DOS diskette. A second diskette contains the debug, linker,
and sample programs. If the DOS diskette is present in diskette
drive A or if DOS resides on the fixed disk, DOS will
automatically be loaded into random access memory when the system
is started or restarted. DOS can also be copied to a formatted
diskette or a fixed disk to provide the same function.
       If automatic program execution is not used each time DOS
is initialized, the user will be asked for the current date and
time. This information will be used to identify the most recent
update to a file. If the AUTOEXEC option is used and "unattended"
operation is desired, date and time prompting can be bypassed.
       DOS Version 2.1 uses approximately 24KB of random access
storage.  This is not an increase over DOS 2.0 but is an increase
over DOS 1.1. This means that additional memory may be required
to permit an application program to be loaded and run on some
systems. In general, 64KB is a minimum memory requirement for DOS
2.1 systems. The recommended memory for IBM PCjr and for a system
with a fixed disk is 128KB or more.
       Prior to running a BASIC language program performing
diskette I/O, one of the two language extensions, Disk BASIC or
Advanced BASIC, must be loaded into memory or be available on the
IBM PCjr BASIC Cartridge.
       Limitations: DOS 2.1 has the same function and requires
the same memory as DOS 2.0.  However, DOS 2.1 uses more memory
than DOS 1.1 (approximately 12KB more). Some programs may require
adding memory to the system or dividing the program into
       Prerequisites:  On IBM PCjr - 64KB memory; one dual-sided
diskette drive; IBM PCjr Connector for TV with a color or black
and white television, or IBM PCjr Adapter Cable for IBM Color
Display with the IBM Color Display or equivalent.
       On IBM Personal Computer - 64KB memory; one single- or
dual-sided diskette drive; IBM Color Display or equivalent with
the IBM Color/Graphics Monitor Adapter, or a color or black and
white television with an RF modulator and the IBM Color/Graphics
Monitor Adapter, or IBM Monochrome Display and IBM Monochrome
Display and Printer Adapter.
       On IBM Personal Computer XT - 128KB memory; one single- or
dual-sided diskette drive; IBM Color Display or equivalent with
the IBM Color/Graphics Monitor Adapter, or a color or black and
white television with an RF modulator and the IBM Color/Graphics
Monitor Adapter, or IBM Monochrome Display and IBM Monochrome
Display and Printer Adapter.
       Data Security: User management is responsible for
evaluation, selection, and implementation of security features,
for administrative procedures, and for appropriate controls in
application systems.
       If sensitive data is sent over external communication
facilities, user management may wish to pursue the application of
       Administrative Information
       Ordering Information: Orders for any quantity may be
accepted by marketing representatives. Orders for less than 20
may be accepted by the IBM Product Centers. Each Product Center
will accept and process orders within its trading area.
       Charges, Terms, and Conditions
       See announcement letter entitled "IBM Personal Computer
and PCjr Charges, Terms, and Conditions" included in this
announcement package.