Message-Id: <199802041443.QAA05352@ankara.duzen.com.tr> Comments: Authenticated sender is From: "S. M. Halloran" Organization: User RFC 822- and 1123-Compliant To: djgpp AT delorie DOT com Date: Wed, 4 Feb 1998 16:44:39 +0200 MIME-Version: 1.0 Content-type: text/plain; charset=US-ASCII Content-transfer-encoding: 7BIT Subject: Re: dubble buffering In-reply-to: <01bd30f9$1418c700$a23470c2@siddiqui> Precedence: bulk > sorry about the ignorance, but what is dubble buffering? *Double* buffering is a concept related to the use of memory caches for reading and writing data to disks (your hard disk). I hope you know what purpose caches serve. Think of caches as a time-saving strategy for accessing both code and data quickly from memory rather than trying to access the disk, which is probably 5-10 (?) times slower if you do the latter. If what you want is in your cache (in memory?), you save time; if not, you have to go to disk to get the parts that you need to use for the moment. This whole notion of time-saving by using caches is I think what prompted Intel to put 14 levels of caches (yes, I am being facetious) in their CPUs so that your code and data could be fetched even faster, if you can believe it, than the time it takes to go from RAM to the CPU. Rather than try to botch any further an explanation of what a cache is or is not or why it would be necessary, you can get a MS-DOS prompt and type in 'help smartdrv' and find the parts related to use of double buffering. It doesn't really explain the purpose of double buffering, only if you should use it; why you are not told 'why' but just 'how' may be a Microsoft customer service policy. I will help a little by directly excerpting certain parts of the help screens related to the use of Microsoft's SMARTDRV. ----------------------------------------------------- SMARTDRV.EXE--Notes Double buffering and conventional memory SMARTDrive's double-buffering component must be loaded in conventional memory. It uses 2K of conventional memory, and cannot be loaded in upper memory. The SMARTDrive disk cache can use either upper memory or conventional memory. For more information, see . Determining whether you need to use double buffering If you use EMM386 or run Windows in 386 enhanced mode, you may need to use double buffering. Double buffering is most commonly required with an SCSI (small computer system interface) hard disk or other device, but can also be necessary with an ESDI (enhanced system device interface) or MCA (microchannel architecture) device. Most hard disks do not need to use double buffering. If you are not sure whether your hard disk needs double buffering, follow these steps: 1 Add the following command to your CONFIG.SYS file if the file does not already contain such a command: device=c:\dos\smartdrv.exe /double_buffer This command must appear before the DEVICE command that starts EMM386, if any. 2 Add the following command to your AUTOEXEC.BAT file if the file does not already contain such a command: c:\dos\smartdrv 3 Run the MemMaker program if you haven't already done so. 4 Use the MEM /C /P command to confirm that upper memory is in use. 5 At the command prompt, type SMARTDRV and then press ENTER. SMARTDrive displays information about your system. 6 Look at the column labeled "Buffering." If any line in this column reads "yes," you need to run the double-buffering component of SMARTDrive. (If your system seems to be running slowly, try adding the /L switch to the SMARTDRV command in AUTOEXEC.BAT.) If every line in the "Buffering" column says "no," you can remove the DEVICE command for SMARTDRV.EXE from your CONFIG.SYS file. If any line in the "Buffering" column contains the character "-", then SMARTDrive is unable to detect whether double buffering is needed. Use the MEM /C /P command to confirm that programs are located in upper memory. -------------------------------------------------------- Let this be the final word, since it was Microsoft that spoke them. :) Mitch Halloran Research (Bio)chemist Duzen Laboratories Group Ankara TURKEY mitch AT duzen DOT com DOT tr other job title: Sequoia's (dob 12-20-95) daddy