Overview

M21 is a multi-user programming system which includes a high-level programming language, comprehensive database management facility, and flexible operating system. The high-level programming language used in M21 is a fast and powerful implementation of the ANSI standard M programming language. The M language is used in general business, financial management, process control, order entry, and other areas of information processing.

Some of M21's main features include the following:

• Conformance to the 1995 ANSI standard.
• A comprehensive package of utility, reporting, and database integrity routines.
• Pre-compilation of code for increased performance.
• Individual process per user takes advantage of symmetrical multi-processing architecture.
• API using TCP/IP for access to M data and routines - uses an ActiveX control so can be used from any Microsoft Windows front end tool including Visual Basic/Delphi etc.
• Efficient internal data and routine caching algorithm, including special area of buffers for jobs hogging the system.
• Networking, Journaling, Interjob Communication and Host operating system file and procedure access.

General Features

• Numeric and String collating sequence globals
• Global data length of 1023 characters
• Local variable length of 32K
• Up to 250 UCIs
• External Calls
• Cross UCI global referencing
• Cross system global referencing
• Global protection
• ANSI standard error trapping mechanism
• MSM compatible error trapping mechanism
• MSM compatible Z commands/functions/special variables
• Cross-system JOB command
• Global translation
• Global replication
• After image journaling - globals and routines
• Before image logging (BIL)
• On-line backup - resilience
• Mnemonic namespaces
• Device translation for foreign language terminal support
• Cross-system UCI mirroring
• Access to UNIX commands from within the M environment
• Configurable database block size
• Ability to run multiple versions of M21 on the same machine
• Multiple UNIX files for a single database
• Database can use UNIX files or raw disk devices

Devices

• Terminals
• Null device for discarding output
• TCP/IP and UDP socket devices, using the ANSI standard socket specification
• Host operating system file access
• Printers using the host operating spool device and queues - dynamically set up
• Inter-job communication using named pipes
• View buffer for direct low level memory and disk access
• Tape devices
• Routine interlocks for synchronization

Networking

M21 to M21 using TCP/IP

DDP to legacy MSM, ISM, DSM-11 and DSM-VAX systems using link level

M21 networks to M21 using a private protocol. However it links to other M implementations using the DEC standard for inter M communications. This protocol is supported by MSM, Caché, ISM, and DSM.

Utilities

• Extensive system configuration using utilities or configuration file parameters - dynamic wherever possible
• Utilities written with silent entry points for calling from other routines
• Vectors to the M21 utilities generated for MSM/ISM/DSM compatibility
• Concurrent backup and full restore capabilities to tape. Full, incremental, journal and BIL
• Link to visual editor
• Interactive routine debugger
• Programmer shell which is also integrated into all utilities
• Database repair
• Database validate
• Recover lost blocks
• Histogram performance monitoring of the M21 system
• Comprehensive system information utilities