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PC Q&A
by Jim Sanders - January 23, 2002 at 23:29:31:
The topic for this months meeting was going to be Linux, but things went wrong. The over-heating AMD Athlon 1.2G CPU finally died. Just like the often heard lament, "But it was working fine the last time I used it!" I turned it off to go to lunch on the day before the club meeting. I pushed the power switch when I returned, and some lights came on, but nobody was home. Conveniently, I had just purchased an Athlon XP 1600+ CPU and motherboard for a new project and had the parts on hand to trouble shoot with. The new CPU got the system running but it was still not stable so on the morning of the meeting I decided to change the motherboard as well. This in fact seemed to make Windows run more reliably, but I was not about to try and do a installation of Linux on a machine that had just undergone heart surgery two hours before. I end up with enough egg on my face doing live demonstrations on hardware that I have some confidence in, this had the potential for complete disaster. I decided to demonstrate the Epson 1650 scanner that I was integrating for a customer instead of the Linux demo. I will do that for the February meeting.As usual we had the Q&A session before the demo. One of the questions I did not know the full answer to and said I would find out. The question was about the BIOS entry "AGP aperture." The question was, "What is the AGP aperture, and what should I set the AGP aperture to?
The following answer is quoted from the VIA web site:
"The AGP aperture is an area of system RAM reserved for use by the AGP card for storing textures if it needs to. The RAM is available for use by the system as normal if not used by the graphics card. This feature was of importance for graphics cards in the past, when cards typically only had 4MB or 8MB of onboard memory. However, as most modern AGP graphics cards now have 32MB or 64MB of SDRAM, the setting is now of much less consequence. It is generally advised to set the AGP aperture to half the system RAM _ i.e. set to 32MB with 64MB of RAM. However, this advice predates the use of systems with more than 64MB of RAM and large graphics cards memories. In most cases you are unlikely to need to set the AGP aperture at more than 32MB, although in order to complete some of the artificial 3DMark200x benchmarks you may need to use an aperture of 64MB to hold all the textures."
This, and a few other articles, leads me to make the following statement; For most people, leave it at the 64Meg default and don't worry about it. For heavy duty gamers, same advice, plus go to the user group for your favorite game and ask if anyone has seen an improvement by changing the value.
On the Epson scanner, a nice piece! At 1600 x 3200 optical resolution, 3.2 Dmax, 48 bit color, built in positive/negative film scanning capability, a nice software package that includes Adobe Photo Elements, a USB interface, and all for about $250, a good buy. A discussion point was whether or not you need that much resolution in your scanner. The answer for most jobs is NO. But when you start talking about scanning a 35mm slide, the answer is yes and more is better. When scanning a 4" x 6" print at 150 DPI in Adobe Photoshop, it takes the scanner about 10 seconds and generates a bit mapped file of 2.69 Megabytes or a JPEG medium compression file of about 225KB. This makes a good looking snapshot when viewed on a 1024x768 monitor. But zoom in even once and you can see it start to pixilate. The same photo scanned at 800 DPI takes the scanner about 65 seconds and generates a bit mapped file of 42.5 Megabytes or a JPEG medium compression file of about 1014KB. From the full screen mode you can zoom in about 6 times before you start getting the jaggies. The same photo scanned at 1600 DPI takes the scanner about 3 min. 45 seconds and generates a bit mapped file of 170 Megabytes or a JPEG medium compression file of about 2550KB. On the print that I was scanning, you could zoom in a little bit more than last time but not see much additional detail.
The transparency unit built into the lid allows you to scan four slides or six negatives in a strip. The light source is wider than that and it should be possible to do a larger film size. For no obvious or stated reason, scans with the transparency unit are considerably slower than the reflective scans. At 3200 DPI, with the cropping box set to .93" x 1.42" you get a 39 Megabyte scan image. Drop it to 1600 DPI, and the size drops to 9.7MB. At the 1600 DPI setting, a slide take four minutes to scan after you have prescanned and set up the crop box. Obviously not a unit that you want to go into volume production with. On the other hand, for a unit that does it all, and does a pretty good job of it, $250 is an attractive price.
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