XMGR  - XMS Memory Manager
UHDD  - Hard Disk drive caching driver
UDVD2 - Optical drive caching driver
RDISK - 2-Gigabyte "RAM Disk" Driver

Last Update : 2018-01-24

Binary: UDRIVERS.ZIP (24.4K)

XMGR, RDISK, UHDD, and UDVD2 are DOS drivers for an 80486+ PC system using MS-DOS V5.0+ or a fully-compatible variant. They are derived from the XHDD/XDVD2 drivers that are now PRIVATE, reasons NOT for discussion again! The Closed-Source and more limited UHDD/UDVD2 driver set will be available for all users.

XMGR is a DOS XMS memory manager. It supports V3.70+ UMBPCI by Uwe Sieber and can load directly into UMBPCI upper-memory. It also runs with JEMM386 or other similar "EMS managers". XMGR follows the V3.0 XMS Specifications and handles up to 4 Gigabytes of memory.

RDISK is a DOS RAM-disk driver. It creates a "fast" disk drive from up to 2 GIGABYTES of XMS memory! The AUTOEXEC.BAT file can copy critical files and programs to the RAM-disk, and DOS can access them at memory speeds. RDISK is a small "load it and forget about it" driver, for users who do not need resizing or other features.

UHDD is a disk caching driver for DOS. It runs up to 14 SATA/IDE UltraDMA disks of any size on up to 5 "Legacy" or Native-PCI IDE controllers. UHDD intercepts and caches Int 13h I-O calls for its disks, A: or B: diskettes, and other Int 13h drivers loaded before UHDD. The UDVD2 driver (below) can call UHDD to cache CD/DVD data files. "Read Ahead" is used for SATA or IDE disks with a 20-MB+ cache (10%+ more speed than old UIDE drivers), and Write Through caching is done, NO delayed output! UHDD's cache uses XMS memory and holds 5 Megabytes to 4 GIGABYTES of data! UHDD accepts digital camera CompactFlash cards as SATA or IDE drives and now handles them as UltraDMA hard disks (not "call the BIOS" units as in old UIDE drivers).

UHDD also offers a basic UltraDMA disk driver (no cache) with its /B switch for tests and other non-caching tasks. The basic UHDD replaces old UDMA or XDMA drivers and offers reliable PCI-bus disk detection, many errors corrected, etc.

UDVD2 is a CD/DVD driver for up to 3 SATA, IDE, or old "PIO mode" CD/DVD drives. It reads CD/DVD data files, plays audio CDs, and can input "raw" (trackwriter) data. UDVD2 can work alone; or if the caching UHDD driver is present, UDVD2 will call it to cache CD/DVD data files for MUCH faster speed! UDVD2 will run with no XMS driver for minimal DOS "game" systems. It can replace old XCDROM or GCDROM drivers and provides reliable PCI-bus drive detection, fast CD/DVD caching via UHDD, many errors corrected, etc.

UHDD and UDVD2 can run AHCI disk/CD/DVD drives on controller ports set to "Legacy", "Compatibility", or "Native IDE" mode. See their README file for full details about these drivers, also for example CONFIG.SYS and AUTOEXEC.BAT files that can be used with them.

Revision History
24-Jan-18 /G switch added to UDVD2/RDISK, so "game" PCs need not load any .SYS drivers from AUTOEXEC. Other drivers unchanged (re-dated only).
7-Jan-18 New XMGR /N32 switch to save low memory, new UHDD /O switch for more speed. Other drivers unchanged, re-dated only.
16-Dec-17 UHDD /P switch added for better protected-mode speed and /G added for DOS games. Improved /R switch for RDISK, UHDD and UDVD2. XMGR unchanged, re-dated only.
4-Dec-17 Initial release of the UHDD/UDVD2 driver set for all users, derived from the XHDD/XDVD2 drivers that are now PRIVATE!