MSX BASIC
Encyclopedia
MSX BASIC is a dialect of the BASIC programming language. It is an extended version of Microsoft
Standard BASIC Version 4.5, and includes support for graphic, music, and various peripherals attached to MSX
Personal Computers. Generally, MSX-BASIC is designed to follow GW-BASIC
, which is one of the standard BASICs running on 16-bit computers. During the creation of MSX-BASIC, a major effort was made to make the system as flexible and expandable as possible.
MSX BASIC came bundled in the ROM
of all MSX computers. At system start-up MSX BASIC is invoked, causing its command prompt to be displayed, unless other software placed in ROM takes control (which is the typical case of game cartridges and disk interfaces, the latter causing the MSX-DOS
prompt to be shown if there is a disk present which contains the DOS system files).
When MSX BASIC is invoked, the ROM code for BIOS
and the BASIC interpreter itself are visible on the lower 32K of the Z80 addressing space. The upper 32K are set to RAM, of which about 23K to 28K are available for BASIC code and data (the exact amount depends on the presence of disk controller and on the MSX-DOS kernel version).
. It has a command line-based Integrated Development Environment (IDE) system; all program lines must be numbered, all non-numbered lines are considered to be commands in direct mode (i.e., to be executed immediately). The user interface is almost completely command line, except for the function key shortcuts at the bottom and an initial copyright notice at the top of the screen.
MSX BASIC 2.1 exists on computers Yamaha YIS-805 and Sanyo MPC-2300 with Cyrillic keyboard and Cyrillic symbols support.
Exploring the MSX BASIC extensibility it was possible to extend MSX BASIC solely via software. A very interesting extension to the MSX BASIC 1.0/1.1 was Screen IV, a tweak of MSX BASIC adding the mixed graphic/text mode Screen 4 (hence its name Screen IV), with 64 x 24 characters and Screen 2 resolution for graphics (256 x 192 pixels, 16 colors).
Microsoft
Microsoft Corporation is an American public multinational corporation headquartered in Redmond, Washington, USA that develops, manufactures, licenses, and supports a wide range of products and services predominantly related to computing through its various product divisions...
Standard BASIC Version 4.5, and includes support for graphic, music, and various peripherals attached to MSX
MSX
MSX was the name of a standardized home computer architecture in the 1980s conceived by Kazuhiko Nishi, then Vice-president at Microsoft Japan and Director at ASCII Corporation...
Personal Computers. Generally, MSX-BASIC is designed to follow GW-BASIC
GW-BASIC
GW-BASIC was a dialect of the programming language BASIC developed by Microsoft from BASICA, originally for Compaq. It is compatible with Microsoft/IBM BASICA, but was disk based and did not need the ROM BASIC. It was bundled with MS-DOS operating systems on IBM PC compatibles by Microsoft...
, which is one of the standard BASICs running on 16-bit computers. During the creation of MSX-BASIC, a major effort was made to make the system as flexible and expandable as possible.
Distribution
Read-only memory
Read-only memory is a class of storage medium used in computers and other electronic devices. Data stored in ROM cannot be modified, or can be modified only slowly or with difficulty, so it is mainly used to distribute firmware .In its strictest sense, ROM refers only...
of all MSX computers. At system start-up MSX BASIC is invoked, causing its command prompt to be displayed, unless other software placed in ROM takes control (which is the typical case of game cartridges and disk interfaces, the latter causing the MSX-DOS
MSX-DOS
MSX-DOS is a Disk operating system developed by Microsoft for the 8-bit home computer standard MSX, and is a cross between MS-DOS rev 1.0 and CP/M.-MSX-DOS:...
prompt to be shown if there is a disk present which contains the DOS system files).
When MSX BASIC is invoked, the ROM code for BIOS
BIOS
In IBM PC compatible computers, the basic input/output system , also known as the System BIOS or ROM BIOS , is a de facto standard defining a firmware interface....
and the BASIC interpreter itself are visible on the lower 32K of the Z80 addressing space. The upper 32K are set to RAM, of which about 23K to 28K are available for BASIC code and data (the exact amount depends on the presence of disk controller and on the MSX-DOS kernel version).
Development Environment
MSX BASIC development environment is very similar to that of the Dartmouth Time Sharing System associated with Dartmouth BASICDartmouth BASIC
Dartmouth BASIC is the original version of the BASIC programming language. It is so named because it was designed and implemented at Dartmouth College...
. It has a command line-based Integrated Development Environment (IDE) system; all program lines must be numbered, all non-numbered lines are considered to be commands in direct mode (i.e., to be executed immediately). The user interface is almost completely command line, except for the function key shortcuts at the bottom and an initial copyright notice at the top of the screen.
Versions of MSX BASIC
Every new version of the MSX computer was bundled with an updated version of MSX BASIC. All versions are backward compatible and provide new capabilities to fully explore the new and extended hardware found on the newer MSX computers.MSX BASIC 1.0 / 1.1 / 1.2
- Bundled with MSX 1.0 / 1.1 / 1.2 computers
- 16 KB in size
- No native support for floppy disk requiring the Disk BASIC cartridge extension (4 KB overhead)
- Support for all available screen modes:
- Screen 0 (text mode 40 x 24 characters)
- Screen 1 (mixed text mode 32 x 24 characters, sprites and colored custom characters)
- Screen 2 (high resolution graphic mode 256 x 192 pixels, 16 colors)
- Screen 3 (low resolution graphic mode 64×48 - 4×4 pixel blocks over the screen 2 resolution)
- Full support for hardware sprites and interruptInterruptIn computing, an interrupt is an asynchronous signal indicating the need for attention or a synchronous event in software indicating the need for a change in execution....
-driven automatic collision detectionCollision detectionCollision detection typically refers to the computational problem of detecting the intersection of two or more objects. While the topic is most often associated with its use in video games and other physical simulations, it also has applications in robotics... - Full support for the General Instruments AY-3-8910 Programmable Sound GeneratorProgrammable sound generatorA Programmable Sound Generator is a sound chip that generates sound waves by synthesizing multiple basic waveforms, and often some kind of noise generator, and combining and mixing these waveforms into a complex waveform, then shaping the amplitude of the resulting waveform using...
(PSG)
MSX BASIC 2.0 / 2.1
- Bundled with MSX 2.0
- 32 KB in size (First 16 KB directly available, second 16 KB in other slot and has to be paged in/out for usage)
- Added support for new available screen modes (Note: the 424 lines can only be displayed in interlace mode):
- Updated Screen 0 (text mode 80 x 24)
- Screen 5 (graphic mode 256 x 212/424 pixels, 16 colors out of 512)
- Screen 6 (graphic mode 512 x 212/424 pixels, 4 colors out of 512)
- Screen 7 (graphic mode 512 x 212/424 pixels, 16 colors out of 512)
- Screen 8 (graphic mode 256 x 212/424 pixels, 256 colors, no palette)
- Added support for multicolored sprites (16 colors)
- Added support for hardware accelerated graphics functions (copy, fill, blittering, etc.)
- Added support for using the lower 32K RAM of the computer (not directly visible because the BIOS and BASIC interpreter ROMs take over the addressing space) as a limited RAM disk (only certain types of files could be saved).
MSX BASIC 2.1 exists on computers Yamaha YIS-805 and Sanyo MPC-2300 with Cyrillic keyboard and Cyrillic symbols support.
MSX BASIC 3.0
- Bundled with MSX 2.0+ (plus)
- 32 KB in size (First 16 KB directly available, second 16 KB in other slot and has to be paged in/out for usage)
- Added command SET SCROLL for smooth, hardware based scrolling in BASIC
- Added support for new available screen modes:
- Screen 10 (graphic mode 256 x 212/424 pixels, 12499 YJK at once + 16 colors out of 512 RGB in ML)
- Screen 11 (graphic mode 256 x 212/424 pixels, 12499 YJK at once + 16 colors out of 512 RGB)
- Screen 12 (graphic mode 256 x 212/424 pixels, 19268 YJK at once)
MSX BASIC 4.0
- Bundled with MSX Turbo R (only released in Japan)
- Added support for screen modes of 512 x 512 (16 colors out of 512) and 256 x 212 (19268 colors)
- Added _PAUSE command to make delays in BASIC independent of the current CPU and clock
- Added extra commands for the PCM device (_PCMPLAY, _PCMREC)
Extensions of MSX BASIC
Since MSX BASIC was meant to be expandable from inception, it was possible to write add-on modules quite easily. Support for specific hardware was commonly added by means of expansion cartridges, which also served as the interface to the hardware in question. MSX Disk-BASIC is an example, bundled in the cartridge that provides the hardware interface to the disk drives, it adds commands to access the floppy disk drives.Exploring the MSX BASIC extensibility it was possible to extend MSX BASIC solely via software. A very interesting extension to the MSX BASIC 1.0/1.1 was Screen IV, a tweak of MSX BASIC adding the mixed graphic/text mode Screen 4 (hence its name Screen IV), with 64 x 24 characters and Screen 2 resolution for graphics (256 x 192 pixels, 16 colors).
External links
- MSX.bas - A Portuguese website focusing completely on development in MSX-BASIC.