American or Taiwanese computers in Japan, but DOS J4.0/V caused some issues on PC compatibles. Its EMS driver only supports IBM's Expanded Memory Adapter. The input method doesn't support the US keyboard nor the Japanese AX keyboard, so it locates some keys at the wrong place. PS/55 keyboards were available from IBM, but it must be used with an AT to PS/2 adapter because AX machines (thus PC/AT clones) generally have the older 5-pin DIN connector. Scrolling text with the common Tseng Labs ET4000 graphics controller makes the screen unreadable. This issue can be fixed by the new /HS=LC switch of $DISP.SYS in DOS J4.07/V. "Some VGA clones did not correctly implement the CRTC address wraparound. Most likely those were Super VGAs with more video memory than the original VGA (i.e. more than 256 KB). Software relying on the address wraparound was very rare and therefore the functionality was not necessarily correctly implemented in hardware. On the other hand, the split screen technique was relatively well documented and well understood, and commercial software (especially games) sometimes used it. It was therefore likely to be tested and properly implemented in hardware." IBM Japan released DOS J5.0/V in October 1991, and DOS J5.0 in December 1991. DOS J5.0 combines Japanese DOS and DOS/V. This is the last version developed for the PS/55 display adapter. DOS J5.02/V was released in March 1992. It added official support for the IBM PS/2 and the US English layout keyboard. The development of MS-DOS 5.0/V was delayed because IBM and Microsoft disputed how to implement the API for input methods. It took a few months to make an agreement that the OEM adaptation kit (OAK) of MS-DOS 5.0/V provided both IAS (Input Assist Subsystem) and MKKC (Microsoft Kana-Kanji Conversion). Microsoft planned to add the AX application support into DOS/V, but cancelled it because its beta release was strongly criticized by users for lacking compatibility. Some PC manufacturers couldn't wait Microsoft's DOS/V. Toshiba developed a DOS/V emulator that could run DOS/V applications on a VGA-equipped J-3100 computer. AST Research Japan and Sharp decided to bundle IBM DOS J5.0/V. Compaq developed own DOS/V drivers, and released their first DOS/V computers in April 1992. On 10 December 1993, Microsoft Japan and IBM Japan released new versions of DOS/V, MS-DOS 6.2/V Upgrade and PC DOS J6.1/V. Although both were released at the same time, they were separately developed. MS-DOS 6.2/V Upgrade