A few scanning tips


Swap file, memory, and disk cache memory usage

In Windows XP, CTRL-ALT-DEL shows the Task Manager, which has a tab for Performance. It shows installed Physical memory as Total, with Available and System Cache (disk cache memory). Available plus System Cache adds to more than Total, the additional memory is in the Page File (least used stuff swapped to disk). The PageFile Usage (PF) is shown at Commit Charge, with current swap size being show as Total (divide by 1024 to get graphed value in MB). PF Peak history and Limit (limited by free disk space) are also shown.

In Windows 9x, use the menu Start - Accessories - System Tools - System Monitor. If you don't find the Monitor, then it was not installed originally. Go to Control Panel - Add/Remove Programs - Windows Setup - Accessories - Details, and select System Monitor, and install from the Windows CD.

If you have not used the 9x Windows System Monitor before, use its menu Edit - Add Item - Memory Manager to add these values to watch:

Allocated Memory Swap File Size
Unused Memory Swap File In Use
Swappable Memory Disk Cache Size
  Maximum Disk Cache

These instantaneous values can be displayed as graphs in the 9x System Monitor, and will show you the real time size of your Swap File and Disk Cache. You can watch it while scanning. As Allocated Memory increases (memory in use), Free Memory decreases (memory available). When Free Memory approaches zero, then the Swap File In Use begins to grow, the disk activity peaks, and the machine slows greatly while waiting on the disk drive. A little swapping is very normal, but a lot is painful. Clicking one of the graphs causes its actual numeric value to show on the Monitor's lower status bar.

Memory Workarounds:

At least 128 megabytes is extremely desirable for a scanner and Win9x, and more for a film scanner. At least 256 MB for WinXP. A good rule of thumb for good performance is those numbers for the system, PLUS additional memory of at least three times the size of the largest image that will be processed. 512 MB is NOT at all unreasonable today for XP and a film scanner. Since memory is so cheap now, I have 640 MB for XP and a film scanner. Older computers (Pentium I or earlier) had memory cache limitations, but since then, motherboard capacity is the only limitation.

Remember when memory was $40 per MB? It's currently only a few cents per MB, and there's really no reason to suffer anymore. Adding memory is the best one single thing you can do to improve your computer, especially for a film scanner.

Copyright © 1997-2003 by Wayne Fulton - All rights are reserved.

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