Loading the Microsoft Mouse Driver 9.0 in Upper Memory (98235)

This article was previously published under Q98235

Version 9.0 of the Microsoft Mouse driver uses an average of 24 kilobytes (K) when loaded. It attempts to load in upper memory by sending a request to MS-DOS for an upper memory block (UMB). If the request to MS-DOS fails, the driver calls the UMB manager (for example, EMM386.EXE) to request a block of memory.

NOTE: A UMB manager must be loaded to move the driver into upper memory.

The entire driver, with the exception of the Program Segment Prefix (PSP) address, is then loaded into upper memory. The PSP resides in conventional memory.