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Locomotive BASIC was a [http://en.wikipedia.org/wiki/BASIC_programming_language BASIC] interpreter for the Amstrad CPC range of computers.
== Description ==
Locomotive BASIC, was one of the best and fastest BASIC implementation implementations of that the era. It featured The language benefited both from a comprehensive graphic capabilities with it's PLOTclean, DRAWwell-thought out implementation of the core language by Locomotive, PAPER, INK, PEN, BORDER, CIRCLE and FILL commandsby the excellent [[firmware]] of the CPC, a feature that was missing in Commodore which lent most of its advanced features to the BASIC.
Unlike the competing Commodore 64, it featured a comprehensive graphic capabilities with its PLOT, DRAW, PAPER, INK, PEN, BORDER and (in [[BASIC 1.1]]) FILL commands. It had a very extensive sound commands, granting almost full control of the [[AY-3-8912]]via the firmware's volume and tone envelope system. With the SOUND command, you could select channels, set envelopes, pitch, noise and volume. That was something unmatched by other computers of that era.
Also there was simple interface for memory menagmentmanagement, with MEMORY and LOAD commands. The later, alowed latter allowed for loading of raw screen data, thus providing easy picture showing. Also, the LOAD command together Both through this (combined with CALL, PEEK and POKE provided an ) and the firmware's [[RSX]] system, it was easy method for mixing basic to mix BASIC and assembly code, granting possibility to speed thereby speeding up BASIC routinesprograms by coding the slowest parts directly in machine code. Many successful programs, witchincluding games such as [[Radzone]] and applications such as [[PowerPage]], being interpreted were inevitably slowmade use of this technique.
With DEF FN, ON variable GOTO and ON variable GOSUB, Locomotive BASIC provided something that could be called "stub the rudiments of a structure programing"structured programming", feature that was beaten only by though nowhere near the extent of the PROCedures of [[BBC Micro's BASIC]].
All in all, if you compare BASIC interpreters of that era, the Locomotive's seems to be the best 'all-rounder' regarding the combination of speed and complexity, and still some of its features were unmatched by others.
== History ==
The CPC implementation of Locomotive BASIC was developed directly from [[Locomotive Software]]'s existing Z80 BASIC. The existence of this is cited as one of the reasons Locomotive requested that [[Amstrad]] change the CPC's processor from a [[6502]] to a [[Z80]].
The 464 shipped with [[BASIC 1.0]] on ROM.
The language was revised and debugged for the 664, 6128 and Plus machines to become [[BASIC 1.1]]. Changes were minor but significant for the programmer, and included:
* DEC$ bug removed (in BASIC 1.0, it required two opening brackets and was undocumented)
* Better handling of string arguments to RSXs (|DIR,"*.BAS" rather than a$="*.BAS":|DIR,@a$)
* FILL command (fill area with solid colour)
* COPYCHR$ function (fetch character from screen)
* Better garbage collection
* Some number-handling bugs removed (e.g. in FOR loops with negative start/end values)
* FRAME (CALL &BD19)
* Extra, optional 'plotting mode' parameter for DRAW/PLOT commands (supported only through control codes on BASIC 1.0)
* GRAPHICS PAPER, GRAPHICS PEN commands
* ON BREAK CONT (disable ESCape)
* CLEAR INPUT (flush keyboard buffer)
Some parts of 'BASIC' were actually housed in the firmware ROM, but were not officially accessible to other programs. This included the line editor.
The 'pure BASIC' parts of Locomotive BASIC - i.e. those not concerned with CPC-specific firmware and hardware features - were upgraded to become Mallard BASIC, the CP/M language shipped with the [[PCW]]. This also featured exceptionally advanced random-access file handling, a feature missing from the CPC.
== Command list ==
