What is MSX?
This page was last modified 19:22, 1 September 2016 by Rderooy. Based on work by Snout and Jorito and others.



MSX is a Zilog Z80-based family of home computers which appeared in autumn 1983 as an attempt to establish a single standard in home computing similar to VHS in video. MSX machines were produced by a large list of industry giants as Sony, Yamaha, Panasonic, Toshiba, Daewoo, and Philips.


The MSX standard was designed by ASCII Corporation in cooperation with Microsoft. The latter provided a firmware version of its BASIC for the machine. Because this BASIC version was an extended version of MicroSoft Basic, it was called "MicroSoft eXtended BASIC", thus explaining the abbreviation MSX.

MSX computers proved to be popular in Asia (Korea, Japan), South America (Brazil, Chile), Europe (Netherlands, France, Spain, Finland) and the former Soviet Union. They were virtually unknown in the USA, however. The only MSX machines ever sold in the USA were an early SpectraVideo model and the Yamaha CX-5M, which while essentially an MSX, was marketed as a musical instrument rather than a home computer.

While MSX did not become the intended worldwide computer standard, it remained a versatile and easy to use computer. Thanks to its rich BASIC instruction set and uncluttered operating system, it proved to be especially useful for educational purposes. The Russian Ministry of Education bought hundreds of MSX1 and MSX2 computers, all grouped into "computerized classroom systems" of 10-16 machines, connected into a simple network. Entire generations of Russian programmers have grown up using these computers.

The MSX1 standard died quietly in 1988, but had already been superseded by the MSX2 standard two years earlier. By then, the MSX2+ standard had also entered the market, followed by the MSX turboR in the early nineties. More than a decade after the turboR, the 1chipMSX was conceived. The name refers to having all the MSX logic programmed into one big FPGA chip. It is debated whether this 1chipMSX with its reprogrammable logic is a real MSX or a kind of emulator, as the chip can also be used to emulate another computer. The fact remains that the 1chipMSX carries the official MSX logo.

The name 'MSX'

According to Kazuhiko Nishi, the 'inventor' of the whole MSX concept, "MSX" can mean a lot more than just MicroSoft eXtended. In an article published in a Japanese business magazine in 1997, he stated that he had used the abbreviation MSX to contract a lot of companies saying that it meant "Matsushita Sony X-machine", in which the X could refer to the company Nishi was talking to at that moment. Nishi also pointed out that he initially wanted to name the standard "NSX" (Nishi Sony X) or "MNX" (Matsushita Nishi X), but the name "NSX" had already been taken by Honda. Following this logic, Nishi could also say that the MS refers to MicroSoft. According to Nishi, Matsushita and Sony are the most important companies that have produced MSX machines and MSX hardware.

Other possible meanings included "Matsushita Sony Shake-hands (X)". But actually, MSX does not really have a meaning; it is just a nice-sounding 3-letter combination. During the MSX fair in Tilburg on 21 April 2001, Nishi gave a lecture in which he stated that MSX meant "Machines [hardware] with Software eXchangeability". A funny observation was that when MSX seemed to be successful, Microsoft said the "MS" in "MSX" meant "MicroSoft", but after 1986, when it was clear that MSX had not become the intended world standard, Microsoft denied that the MS in MSX referred to their name.


MSX represents a hybrid of a videogame console and a generic CP/M-80 machine. Its main CPU is a Zilog Z80A running at 3.58MHz. The video subsystem is built around a TMS9918 or TMS9928 VDP chip, which was also used in the Texas Instruments TI-99/4, Colecovision, and Coleco Adam computers. In later MSX models this chip was upgraded to the V9938 (MSX2) and V9958 (MSX2+ and TurboR). The latest version of this chip is the V9990, which unlike them, is not upwards compatible with its predecessors. The audio system is handled by the AY-3-8910 chip by General Instruments, the same one used in the Sinclair ZXSpectrum128. The AY-3-8910 provides 3 channels of synthesized sound, noise generation, and two general purpose parallel I/O ports which are used for joysticks and some other things in the MSX design. Due to their hardware structure, MSX machines were perfectly suitable for games, and many good games were either written or ported to them.

Nowadays, there are many expansions for the MSX system, such as the Moonsound cartridge which is based on the OPL4 chip, the GFX9000 cartridge based on the aforementioned V9990, SCSI and IDE interfaces. New hardware developments are still in the pipeline. It is not uncommon to distribute new games on cartridges. The VSU project aims to provide an all-in-one expansion, combining OPL4, V9990 and V9958 chips.

A different concept

The main difference between the MSX and its contemporary counterparts is the presence of a very well-developed hardware abstraction layer implemented as the MSX-BIOS. It provides extensibility, device independence and instant plug & play with zero user intervention. The MSX technical handbook states that chips of the MSX system (except for the VDP) can be replaced by different ones, and the BIOS I/O routines can be rewritten to accommodate the changes accordingly, making the differences transparent for the user programs.