FreeDOS help system (hhstndrd 1.0.8 en)[udma2]

Command: udma2.sys / udma2s.sys

UDMA2.SYS / UDMA2S.SYS are DOS hard-disk caching driver for UltraDMA hard-disks. UDMA2.SYS / UDMA2S.SYS has to be loaded in CONFIG.SYS / FDCONFIG.SYS. When FreeDOS is already running, you can load UDMA2.SYS / UDMA2S.SYS later with DEVLOAD. UDMA2.SYS / UDMA2S.SYS are out of date. There is NO MORE support by the author! You should use UIDE.SYS instead.


DEVICE = [path]UDMA2.SYS [/O] [/L] [/S] [...] DEVICE = [path]UDMA2S.SYS [/L] [/S] [...] DEVICEHIGH = [path]UDMA2.SYS [/O] [/L] [/S] [...] DEVICEHIGH = [path]UDMA2S.SYS [/L] [/S] [...]


/O For UDMA2.SYS only, enables output overlap. This REQUIRES an XMS manager (HIMEMX, etc.) and 128K of XMS memory. If /B is also specified, or if XMS is not available, overlap will NOT be enabled, as UDMA2.SYS must then use "DMA only" mode. /L Limits DMA to "low memory" below 640K. /L is REQUIRED to use the UMBPCI upper-memory driver, or any similar drivers whose upper-memory areas do not support DMA. If /L is specified, UDMA2. SYS or UDMA2S.SYS must reside in LOW memory (as their command- list is accessed via DMA), or the driver will ABORT loading! /L causes I/O requests past 640K to go through the driver's XMS buffer. If /B is specified with /L or if XMS memory is not available, such I/O is "passed" to the BIOS for execution. /S For UDMA2.SYS, enables the driver local-stack for "DMA only" mode. For UDMA2S.SYS, enables the local-stack for all cases. NOTE that the two drivers handle /S differently! UDMA2S.SYS usually does not enable a stack (for compatiblity with old versions!) and requires /S whenever a stack is wanted. UDMA2.SYS always sets a stack (and ignores /S) for normal or output-overlap usage, so it requires /S merely for "DMA only" mode. /S is meant for systems with one or more user programs which set "short" run-time stacks. /S and /B are independent and both may be specified together. /B Causes XMS memory to be IGNORED, for "backward compatibility". /B forces UDMA2.SYS or UDMA2S.SYS to use "DMA only" mode. Thus, /B cancels /O (UDMA2.SYS output overlap is not enabled), causes the initialization "read tests" in UDMA2.SYS to be omitted, and also affects /L as noted above. /Mn Specifies the MAXIMUM UltraDMA "mode" to be used by all disks, where n is a number between 0 and 7, as follows: 0 = ATA-16, 16 MB/sec. 4 = ATA-66, 66 MB/sec. 1 = ATA-25, 25 MB/sec. 5 = ATA-100, 100 MB/sec. 2 = ATA-33, 33 MB/sec. 6 = ATA-133, 133 MB/sec. 3 = ATA-44, 44 MB/sec. 7 = ATA-166, 166 MB/sec. Disks designed to a "mode" LESS than the given value will be limited to their own highest "mode". At present, "mode 7" ATA-166 is not yet implemented, but any driver CAN handle it if UltraDMA disks ever use it. /X For UDMA2.SYS only, disables initialization "read tests". This switch is a LAST-chance "scheme" of forcing UDMA2.SYS to load on "problem" systems! Any errors detected by the "read tests" should be CORRECTED, wherever possible! For each switch, a dash may replace the slash, and lower-case letters may be used.


UDMA2.SYS is the most full-featured driver. It offers "output overlap" which buffers all output and does NOT await output end, so user work may overlap the DMA! Depending on the user's system and software, output overlap can yield a significant speed boost. For any output error or if a 400-msec timer expires, an error message will display. Output overlap must be enabled with a /O in the CONFIG.SYS line that loads UDMA2.SYS (see above for switch options). UDMA2S.SYS is the PREFERRED "small driver", for systems not using out- put overlap. It omits overlap and initialization "read tests", thus it achieves an object-file size of 3072 bytes. All other capabilities of the larger UDMA2.SYS (including an 80386 test) are retained. UDMA2S.SYS uses the same 640 byte resident "core" as UDMA.SYS or UDMAJR.SYS



See also:

autoexec.bat config.sys devload fdconfig.sys himemx (udma.sys) uide.sys (xdma.sys) ------------------------------------------------------------------------------ Copyright (C) 2007 Jack Ellis, updated 2011 by W. Spiegl. This file is derived from the FreeDOS Spec Command HOWTO. See the file H2Cpying for copying conditions.