AX (Architecture eXtended) was a Japanese computing initiative starting in around 1986 to allow PCs to handle double-byte (DBCS) Japanese text via special hardware chips, whilst allowing compatibility with software written for foreign IBM PCs. It was developed by a consortium including ASCII Corporation, Sony, Hitachi, Sharp, Oki, Casio, Canon, Kyocera, Sanyo, Mitsubishi Electric, etc. with cooperation of Microsoft. but notably excluding Toshiba and Fujitsu (who were hence the 'opposition'). At that time, NEC PC-9801 system was the dominant PC architecture in the Japanese PC market because the IBM PC/AT could not handle the Japanese language. However, NEC did not tolerate PC-9801 compatible machines and was fighting court battles with Epson which was the only PC-9801 compatible machine vendor. Therefore opposing vendors desperately needed a standard specification for Japanese capable PCs.
To display Kanji characters with sufficient clarity, AX machines had JEGA screens with a resolution of 640x480 rather than the 640x350 standard EGA resolution prevalent elsewhere at the time. Users could typically switch between Japanese and English modes by typing 'JP' and 'US', which would also invoke the AX-BIOS and an IME enabling the input of Japanese characters.
However, soon after the release of the AX, IBM released the VGA standard with which AX was obviously not compatible. Consequently, the AX consortium had to design a compatible AX-VGA. AX-VGA/H was a hardware implementation with AX-BIOS, whereas AX-VGA/S was a software emulation.
As a result, the average price tag of AX computers was much higher than NEC PC-9801 ones, and so NEC PC-9801 remained the most popular system in Japan. AX later came to be superseded by IBM's DOS/V, which accomplished the same goals purely in software thanks to advances in typical PC capabilities such as memory, speed, etc.