Maximum CD 1999 January

home *** CD-ROM | disk | FTP | other *** search

/ Maximum CD 1999 January / maximum-cd-1999-01.iso / Drivers / CD-ROM / Sony / CORELCDX.TXT < prev next >

Wrap

Text File | 1995-01-03 | 10.3 KB | 276 lines

About CorelCDX ============== To work with your CD-ROM drives, you require a CD-ROM extensions program such as CorelCDX. CD-ROM extensions programs interpret, for DOS, data read from High Sierra and ISO-9660 formatted CD-ROM discs. Unlike other CD-ROM extensions programs, CorelCDX also caches CD-ROM data. Applications can access cached data faster than re-reading the CD-ROM disc. Table of Contents ----------------- 1. Loading and Unloading CorelCDX 2. CorelCDX Caching 3. Configuring CorelCDX 1. Loading and Unloading CorelCDX ----------------------------------- CorelCDX is loaded from the AUTOEXEC.BAT file during the system startup. The configuration of CorelCDX is determined by its command line switches, which are described in the topic, "Configuring CorelCDX". If you need to free the memory or drive letters used by CorelCDX, you can unload CorelCDX. The next time you restart your system, CorelCDX is loaded again. NOTE: CorelCDX may not unload if other TSR programs were installed after CorelCDX was loaded. If problems occur, unload the other TSR programs and then try to unload CorelCDX again. To unload CorelCDX, enter the following at the command prompt: CORELCDX /UNLOAD. 2. CorelCDX Caching --------------------- CorelCDX includes several types of caches to provide faster access to frequently used CD-ROM data. Path table, directory, and data caches provide conventional or expanded memory caching. As an extension to CorelCDX, CDXCACHE provides an extended memory data cache. The path table cache stores information about the name and location of each directory on the CD-ROM disc. Each path table cache buffer accommodates approximately 100 sub-directories. The directory cache stores information such as the name and location of the files in each directory on the CD-ROM disc. Each directory cache buffer accommodates approximately 40 to 50 files. The data cache stores the contents of recently accessed files from the CD-ROM disc and any data that's expected to be required next. CorelCDX uses a read-ahead plus least recently used (LRU) algorithm for its data cache: frequently used data remains in the cache and infrequently used data is discarded from the cache. Data is read into the cache in sector blocks. CDXCACHE, if enabled, is loaded at the same time as CorelCDX. This cache stores information recently read from CD-ROM drives in extended memory. CDXCACHE, like the data cache, uses an LRU algorithm to determine the contents of the cache. CDXCACHE can cache the first 16 CD-ROM drives connected to your system. The cache page size affects the maximum cacheable sector address. CDXCACHE works best with database type applications, which repeatedly read information from the same areas of a CD-ROM disc. CDXCACHE versus SMARTDrive: Both CDXCACHE and Microsoft's SMARTDrive program use extended memory caching. If you're using SMARTDrive version 5.0, provided with MS-DOS 6.2, you can use SMARTDrive rather than CDXCACHE. However, CDXCACHE has smaller overhead and operates faster than SMARTDrive. SMARTDRV.EXE 5.0 is designed to work exclusively with Microsoft's MSCDEX CD-ROM driver. However, Corel's PATCH_SD.COM modifies SMARTDRV.EXE to recognize CorelCDX as a valid CD-ROM driver. PATCH_SD creates a copy of the existing SMARTDRV.EXE program and stores the copy as SMARTDRV.MSC. PATCH_SD works only if the size of SMARTDRV.EXE is equal to 45145 bytes. To modify SMARTDrive to recognize CorelCDX: 1. Enter the following at the command prompt: PATCH_SD. 2. Check your AUTOEXEC.BAT file to ensure that CorelCDX is loaded before SMARTDrive. If SMARTDrive is loaded first, it won't find, and therefore cache, CD-ROM drives. Since SMARTDrive is loaded after CorelCDX, you can't use the CorelCDX /UNLOAD command. 3. Disable the CDXCACHE by setting the CorelCDX command line option /XMSSIZE to 0. If you don't disable this cache, both CDXCACHE and SMARTDrive will cache data, using twice the necessary amount of extended memory. 4. Reboot your system to reinstall SMARTDRV.EXE. 3. Configuring CorelCDX ------------------------- CorelCDX is configured using command line switches. Some of these switches affect the caching features. For more information, see the topic, "CorelCDX Caching". The CorelCDX command syntax includes the path to the location of CorelCDX and several switches. For example, the following command indicates that CorelCDX is located in the CORELDRV directory: C:\CORELDRV\CORELCDX [options] /CACHE:pt;dir;data Defines the number of cache buffers allocated, in blocks, to the path table, directory, and data caches, respectively. Typically, the /M option is used rather than /CACHE. However, the /CACHE option allows more precise control over the use of allocated cache buffers. If both the /CACHE and /M options are used, the /CACHE values override the /M value. You can set path table and directory caches from 2 to 64 blocks. Each block requires 2K. The data cache can be set from 2 to 64 blocks. The size of each block is determined by the /DATABLK option. Minimum, maximum, and alignment requirements may require that the actual number of buffers differ slightly from those you specify. /DATABLK:sectors Defines the number of 2K sectors assigned to each data cache block. You can set this value to 1, 2, 4, or 8 sectors. If you don't specify a size, the data cache block size is set to 2 sectors by default. This option is useful for applications that read data from compact discs in contiguous segments. Unless you're using CDXCACHE, setting the /DATABLK value to 1 disables read-ahead caching. However, an additional 4K of conventional memory is required. The internal read-ahead caching logic of some CD-ROM drives may be adversely affected by changing the default data cache block size. /D:name... Displays the required name of the CD-ROM device driver. If you enter more than one CD-ROM device driver name, separate each name with a comma and remove any blanks between names. If you're using Corel's DOS CD-ROM device drivers, names are numbered starting from MSCD001. If you're using Corel's NetWare CD-ROM device drivers, names are numbered starting from MSCD099. If driver names aren't included in the command line, CorelCDX will try to locate and initialize the CD-ROM device drivers named, by default, MSCD001 or MSCD099. /E:value Indicates whether code, data, or cache buffers are to be stored in expanded memory. This option doesn't affect cache buffers used by CDXCACHE. The option /E:1 loads code and data into expanded memory. Only a small footprint remains resident in conventional memory. This option may be incompatible with some CD-ROM applications; for example, those that perform absolute disk reads into expanded memory buffers. The options /E:2 and /E load only cache buffers into expanded memory. The option /E:3 loads code, data, and cache buffers into expanded memory. In rare cases, this value may cause problems when you try to read data from a CD-ROM drive. Some applications, when loaded in expanded memory, may create memory conflicts. If you experience problems, change the option to either /E or /E:2. If cache buffers are loaded in expanded memory, a small amount of conventional memory may be allocated to store required tables, and so on. To make the most efficient use of allocated memory, the driver may slightly increase the number of specified cache buffers. /CORELDRV=NO This option when specified =NO will disable the unique I/O Call made by CorelCDX during it's initailization stage. Some IDE CD-ROM drivers are unable to handle the unique I/O Call and hang. If this happens, add the /CORELDRV=NO switch on the CorelCDX statement in the Autoexec.bat. Default is YES and no command line switch is needed. /FILES:num Sets the maximum number of CD-ROM files that can be open at the same time. Each file requires approximately 16 bytes. If you don't specify this option, the maximum number of open files is set to the same value as the FILES command in your CONFIG.SYS file. /L:letter Indicates the drive letter, from A to Z, at which CorelCDX starts assigning letters to CD-ROM drives. If the letter you specify isn't available, the next available drive letter is used. This option is useful for software that requires specific drive letters for CD-ROM drives. /M:buffers Indicates the approximate number of cache buffers allocated, in blocks, for all CD-ROM drives. Typically, the /M option is used rather than /CACHE. However, the /CACHE option allows more precise control over the use of allocated cache buffers. If both the /CACHE and /M options are used, the /CACHE values override the /M value. /NOFILE Prevents CorelCDX from looking for a CRLSCSI.INI file for configuration options. This file isn't required when you configure CorelCDX using command line switches. /SHARE /S Permits CD-ROM drive sharing with Windows for Workgroups. /VERBOSE /VB Displays information onscreen about CorelCDX as it's loading during the system boot. /XMSBLOCK:size Sets the maximum size of read request in sectors that will be cached by CDXCACHE. The cache performance may benefit from larger values. However, the cache may fill up more quickly. A size of 4 is recommended. /XMSPAGE:sectors Indicates the number of sectors per cache page, which determines the read-ahead operations. This option affects only CDXCACHE. The value of 4 is recommended for smaller cache sizes; it's more important to cache separate disk reads than to perform read-aheads. Use the value 8 for larger cache sizes; more data is stored in one operation. /XMSSIZE:size Indicates the size, in kilobytes, of the CDXCACHE cache. Set the size to 0 to disable this cache. A size of -1 creates a default cache size equal to one-quarter of the free extended memory. You can also set the size to a value from 64 to 16384.