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MSX is a standardized home computer architecture, announced by Microsoft and ASCII Corporation on June 16, 1983.[1][2] It was initially conceived by Microsoft as a product for the Eastern sector, and jointly marketed by Kazuhiko Nishi, then vice-president at Microsoft and director at ASCII Corporation.[3] Microsoft and Nishi conceived the project as an attempt to create unified standards among various home computing system manufacturers of the period, in the same fashion as the VHS standard for home video tape machines.[4][5]

MSX systems were popular in Japan and several other countries. Sony was the primary manufacturer of MSX systems at the time of release, and throughout most of the products’ lifespan, producing more units than any other manufacturer. Eventually 5 million MSX-based units were sold in Japan alone. Despite Microsoft’s involvement, few MSX-based machines were released in the United States.[6]

The meaning of the acronym MSX remains a matter of debate. In 2001, Kazuhiko Nishi recalled that many assumed that it was derived from “Microsoft Extended”, referring to the built-in Microsoft Extended BASIC (MSX BASIC). Others believed that it stood for "Matsushita-Sony". He said that the team’s original definition was "Machines with Software eXchangeability".[7] This seems plausible, although, in 1985, he gave a conflicting definition, that he named MSX after the MX missile.[8]

Before the success of Nintendo’s Family Computer, MSX was the platform for which major Japanese game studios such as Konami and Hudson Soft produced video games. The Metal Gear series, for example, was first written for MSX hardware.[9]

Phillips Music Module

The MSXVR is a computer released in 2020 and compatible with the MSX family of computers. Like the latest Zenmix game consoles, it is also based on a Raspberri Pi card with additional circuitry to connect the original MSX peripherals.

System specifications

MSX[28] MSX2 MSX2+ MSX TurboR
Release Worldwide (1983) Worldwide (1985) Only officially in Japan (available in Europe and Brazil via upgrades) (1988) Only Japan (1990)
Processor Zilog Z80A running at 3.58 MHz Zilog Z80A running at 3.58 MHz Zilog Z80-compatible running at 3.58 MHz (the MSX2+ models from Panasonic can be se

The keyboard is a functionally separate unit which could be connected by non-multiplexed and multiplexed interfaces. Multiplexed keyboard units feature additional data direction line, allowing sending scan line number to the keyboard using same data lines used for return scan code, decreasing overall number of wires between keyboard and machine. Non-multiplexed interface is usually used for internal keyboards (and some external keyboards, like Panasonic CF-3300); multiplexed interface is used for external keyboards (e.g. in Yamaha YIS805 model).

The keyboard is organized as a matrix with maximum 11 input lines and 8 output lines, accounting for maximum 88 keys (including all control, numerical and alphanumerical keys). Each scan line is regularly queried to identify the state of the keys on the line; query speed is identified by the system interrupt frequency. Such organization allows system to sense state of each key, not exhibiting notorious problem with 8042 microcontroller-based keyboards when pressing several keys simultaneously (usually more than 3) generates wrong input characters, or renders inability to sense the press of more keys.

Due to the keyboard scan being controlled by the system interrupts, one of the troubleshooting hints when an MSX machine does not display any image (assuming power is present) is to press the CAPS key to see if the respective LED toggles. If it does not toggle, the system is likely suffering a more serious problem than just lack of image on the screen (i.e. the problem with video cable or video display interface in overall).

In 2009 Kamil Karimov designed the adapter board[29] to connect PS/2 keyboard to the multiplexed MSX keyboard interface. The firmware embedded into its ATTiny chip was tailored for Daewoo CPC machines.

In 2011 AGE Labs embedded a PS/2 keyboard controller unit, based on Microchip microcontroller, into its GR8BIT do-it-yourself machine. Its firmware is developed to directly convert PS/2 scan codes to the MSX keyboard scan codes. Thus it is fully transparent to the applications, allowing use of the controller unit with different MSX-compatible machines and for different localization setups.[20]

Cartridges

MSX standard requires at least 1 cartridge slot, most MSX models have 2. These slots[30] are interchangeable, so in most cases it makes no difference in which slot a cartridge is inserted. The physical connector is a 50 pin (2 x 25 contacts), standard 2.54 mm (0.1 inch) pitch edge connector. Using these cartridge slots, a wide variety of peripherals could be connected.

Regular game cartridges are about the size of an audio cassette (so-called "Konami size"). Despite their higher cost, this was a popular format due to its reliability and ease of use.

Around 1985, Hudson Soft released the credit card-sized Bee Card, which was meant as a cheaper and more convenient alternative to ROM cartridges. But it was a commercial failure, and very few titles were released on the format.

Source files[31] for development of the MSX cartridges are available from AGE Labs for EAGLE.

Floppy disk drives

MSX systems generally did not have a built-in disk drive, so games were published mainly on cartridge and cassette tape.[10] Sony created a battery backed RAM cartridge the HBI-55 "data cartridge" for some computers in their "Hit-Bit" line of MSX systems, that could be used to store programs or data as an alternative to cassette tapes.[32]

Floppy disk drives were available for MSX however, in the form of a cartridge containing the disk interface electronics and a BIOS extension ROM (the floppy disk drive interface), connected to an external case with the drive. In South-America, many of these systems used a 5.25 in (133 mm) floppy disk drive, but in Europe, 3.5 in (89 mm) drives were more popular. In Japan, some MSX1 systems included a built-in 3.5" disk drive, like the Panasonic (previously named Matsushita) CF-3000. In Europe, a range of Philips MSX2 systems NMS 8230, 8235, 8245, 8250 and above featured either 360 or 720 Kb 3.5" floppy drives.

In 1985, the MSX2 was released, and these systems often (but not always) included a built-in 3.5" disk drive too. Consequently the popular media for games and other software shifted to floppy disks.

The MSX-DOS disk operating system had internal software mechanisms much like CP/M (so CP/M software could be ported reasonably easily), but had a file system compatible with MS-DOS. Its user commands were also similar to early MS-DOS versions. In this way, Microsoft could promote MSX for home use while promoting MS-DOS based personal computers in office environments.[33]

The MSX 3.5" floppy disks are directly compatible with MS-DOS (although some details like file undeletion and boot sector code were different). Like MS-DOS 1, MSX disks (formatted) under MSX-DOS 1 have no support for subdirectories.[34]

In September 2012, AGE Labs extended the standard by including support for 1.44Mb 3.5” format. The 1.44Mb diskette size goes in two configurations: Standard (1 sector per cluster, 9 FAT sectors), and Compatible (4 sectors per cluster, 3 FAT sectors).[35]

MSX-Audio

  • Yamaha Y8950, commercially released as:
    • Panasonic: MSX-Audio FS-CA1 (32Kb of SampleRAM, 32KB of AudioROM)
    • Philips: Music Module NMS-1205 (32KB of SampleRAM, no MSX-Audio BIOS)
    • Toshiba: MSX FM-synthesizer Unit HX-MU900 (no sample RAM, no MSX-Audio BIOS)
  • 9 channels FM or 6 channels FM + 5 drums. YM3526 compatible.
  • ADPCM record and play, with Hardware acceleration
  • Can be upgraded to 256 KB of SampleRAM

MSX-Music

  • Yamaha YM2413 (OPLL), also known as:
    • MSX-Music (standard name)
    • Panasonic: FM-PAC
    • Zemina: Music Box
    • Checkmark: FM-Stereo-Pak
    • DDX: FMX
    • Tecnobytes: FM Sound Stereo (contains the compatible U3567 chip)
  • 9 channels FM or 6 channels FM + 5 dru

    The keyboard is organized as a matrix with maximum 11 input lines and 8 output lines, accounting for maximum 88 keys (including all control, numerical and alphanumerical keys). Each scan line is regularly queried to identify the state of the keys on the line; query speed is identified by the system interrupt frequency. Such organization allows system to sense state of each key, not exhibiting notorious problem with 8042 microcontroller-based keyboards when pressing several keys simultaneously (usually more than 3) generates wrong input characters, or renders inability to sense the press of more keys.

    Due to the keyboard scan being controlled by the system interrupts, one of the troubleshooting hints when an MSX machine does not display any image (assuming power is present) is to press the CAPS key to see if the respective LED toggles. If it does not toggle, the system is likely suffering a more serious problem than just lack of image on the screen (i.e. the problem with video cable or video display interface in overall).

    In 2009 Kamil Karimov designed the adapter board[29] to connect PS/2 keyboard to the multiplexed MSX keyboard interface. The firmware embedded into its ATTiny chip was tailored for Daewoo CPC machines.

    In 2011 AGE Labs embedded a PS/2 keyboard controller unit, based on Microchip microcontroller, into its GR8BIT do-it-yourself machine. Its firmware is developed to directly convert PS/2 scan codes to the MSX keyboard scan codes. Thus it is fully transparent to the applications, allowing use of the controller unit with different MSX-compatible machines and for different localization setups.[20]

    MSX standard requires at least 1 cartridge slot, most MSX models have 2. These slots[30] are interchangeable, so in most cases it makes no difference in which slot a cartridge is inserted. The physical connector is a 50 pin (2 x 25 contacts), standard 2.54 mm (0.1 inch) pitch edge connector. Using these cartridge slots, a wide variety of peripherals could be connected.

    Regular game cartridges are about the size of an audio cassette (so-called "Konami size"). Despite their higher cost, this was a popular format due to its reliability and ease of use.

    Around 1985, audio cassette (so-called "Konami size"). Despite their higher cost, this was a popular format due to its reliability and ease of use.

    Around 1985, Hudson Soft released the credit card-sized Bee Card, which was meant as a cheaper and more convenient alternative to ROM cartridges. But it was a commercial failure, and very few titles were released on the format.

    Source files[31] for development of the MSX cartridges are available from AGE Labs for EAGLE.

    MSX systems generally did not have a built-in disk drive, so games were published mainly on cartridge and cassette tape.[10] Sony created a battery backed RAM cartridge the HBI-55 "data cartridge" for some computers in their "Hit-Bit" line of MSX systems, that could be used to store programs or data as an alternative to cassette tapes.[32]

    Floppy disk drives were available for MSX however, in the form of a cartridge containing the disk interface electronics and a BIOS extension ROM (the floppy disk drive interface), connected to an external case with the drive. In South-America, many of these systems used

    Floppy disk drives were available for MSX however, in the form of a cartridge containing the disk interface electronics and a BIOS extension ROM (the floppy disk drive interface), connected to an external case with the drive. In South-America, many of these systems used a 5.25 in (133 mm) floppy disk drive, but in Europe, 3.5 in (89 mm) drives were more popular. In Japan, some MSX1 systems included a built-in 3.5" disk drive, like the Panasonic (previously named Matsushita) CF-3000. In Europe, a range of Philips MSX2 systems NMS 8230, 8235, 8245, 8250 and above featured either 360 or 720 Kb 3.5" floppy drives.

    In 1985, the MSX2 was released, and these systems often (but not always) included a built-in 3.5" disk drive too. Consequently the popular media for games and other software shifted to floppy disks.

    The MSX-DOS disk operating system had internal software mechanisms much like CP/M (so CP/M software could be ported reasonably easily), but had a file system compatible with MS-DOS. Its user commands were also similar to early MS-DOS versions. In this way, Microsoft could promote MSX for home use while promoting MS-DOS based personal computers in office environments.[33]

    The MSX 3.5" floppy disks are directly compatible with MS-DOS (although some details like file undeletion and boot sector code were different). Like MS-DOS 1, MSX disks (formatted) under MSX-DOS 1 have no support for subdirectories.[34]

    In September 2012, AGE Labs extended the standard by including support for 1.44Mb 3.5” format. The 1.44Mb diskette size goes in two configurations: Standard (1 sector per cluster, 9 FAT sectors), and Compatible (4 sectors per cluster, 3 FAT sectors).[35]

    MSX computers are emulated on many platforms today. Early MSX emulators were often based on the code of the pioneer fMSX, a portable MSX emulator by Marat Fayzullin. Many emulators removed Fayzullin's Z80 emulation code entirely in later versions to avoid legal problems, as at the time fMSX wasn't free software. Somewhat later fMSX source code became free for non-profit use; however a license was still required for commercial use. On December 31 2013, the Windows version of fMSX 3.7 was released, free for anyone to use.[36]

    The official MSX emulator MSXPLAYer (in Japanese) is produced by the MSX Association, of which the inventor of the MSX standard, Kazuhiko Nishi, is the president.

    As of version 0.146.u, MESS currently supports 90 percent of all MSX Versions.

    Virtual Console

    In February 2007, Nintendo of Japan announced that MSX games will be available for the Wii's Virtual Console emulator. It was confirmed that the games would cost 700 Wii Points and will become available from the middle of 2007. It also became available for the Wii U on December 25, 2013. Ultimately 13 games, mainly Konami titles, for the Wii plus 1 for the Wii U were released for the service in Japan only.


    List of MSX-emulators

    Name Actual version Date System Platform License Website
    blueMSX 2.8.2 14 August 2009 MSX, MSX2, MSX2+, MSX TurboR,

    SpectraVideo SVI318/328, ColecoVision, Sega SG-1000

    Windows GPL [1]
    CocoaMSX <

    The official MSX emulator MSXPLAYer (in Japanese) is produced by the MSX Association, of which the inventor of the MSX standard, Kazuhiko Nishi, is the president.

    As of version 0.146.u, MESS currently supports 90 percent of all MSX Versions.

    In February 2007, Nintendo of Japan announced that MSX games will be available for the Wii's Virtual Console emulator. It was confirmed that the games would cost 700 Wii Points and will become available from the middle of 2007. It also became available for the Wii U on December 25, 2013. Ultimately 13 games, mainly Konami titles, for the Wii plus 1 for the Wii U were released for the service in Japan only.


    List of MSX-emulators