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With integrating the L2 cache into the die, there was some confusion regarding the functionality of Error Checking and Correction on the L2 cache level. Currently all high-end microprocessors are using Error Checking and Correction. ECC in SRAM is becoming more and more important for the reason of so-called soft errors caused by cosmic rays. The probability for these soft errors increases with the density of any SRAM array, in other words, the larger the L2 cache, the higher is the probability of a soft error. Soft errors are caused when a cosmic ray hits an open bit line which can cause flipping of a bit from 0 to 1 or vice versa.

In most cases, the heatsink / fan combination will provide some shielding against cosmic rays but even a massive block of copper on the front will leave the backplane of the CPU exposed and, especially with aluminum cases, there is hardly any shielding at all.

The BIOS setting pertaining to L2 ECC checking enabled / disabled appears to have no function assigned to it, though. We ran a few L2 cache benchmarks with the Athlon XP2800+ but we were not able to detect any performance Difference with ECC enabled over Disabled which leads us to conclude that the setting is one of those that were simply forgotten and have no more bearing on the current system / cache architecture.

The left column shows SiSoft Sandra L2 Cache benchmark results with ECC enabled, the column on the right shows the same system without ECC. The results are virtually indistinguishable from each other, minor discrepancies can be explained by different temperatures at the time of the benchmarking.

Quick Power On Self Test (Enabled, Disabled for installation and trouble shooting)

During the Power On Self Test (POST) the system BIOS performs a check of all system devices and chipset registers as well as some variable parameters as DIMM slot initialization, memory bank occupancy and state machine. Included in the POST are also recognition of the CPU, keyboard and mouse. The BIOS has a copy of the checksum of the expected configuration and if the hardware encountered does not match, it will generate a checksum error. During the POST, the BIOS does extensive checking of all hardware parameters, including triple memory counts which, in some cases, can occupy quite some time. Most BIOS offer, however, the option of disabling the thorough checking of all parameters and bypassing of some sections by selecting Quick Power On Self Test. In this case, e.g. the memory is counted only once. For the initial setup of a system, Quick POST should be disabled to allow the system to check all parameters. If a system is fully configured, there is no need to run the full POST on a routine basis.

These entries are self explanatory and can be used to select the sequence in which bootable drives are searched for an operating systems. In order to speed up booting, the best selection is to start with the primary hard drive which, in most cases, will be C:

In this case, the BIOS will not even access the floppy drive for a bootable disk. Another advantage is that, particularly in a corporate environment, virus proliferation happens primarily via floppy. If an infected floppy is left in the drive and accidentally activated on boot-up, no virus protection will be available to quarantine the virus which may become resident in memory and, upon removing the disk and continuing to boot, will infect the HDD bootsector. There is no reason to be concerned about not being able to boot from a floppy in case of a HDD failure or reinstallation of the operating system since the BIOS will be accessible anyway, allowing to temporarily reset the options and make A: the first boot device.

Swap Floppy Drive (some neat possibilities)

In the 386 computers, the transition from the large 5 ¼ inch drives and their floppy (which is where the name comes from) disks to the smaller 3 ½ inch drives that are (still) standard took place. This is over 10 years ago and still, there are enough manufacturers unable to read the signs of time and who still supply their mainboards with floppy cables equipped with the bulky connectors.

In addition, even though hardly anyone uses two floppy drives, all current floppy disk controllers are offering support for 2 channels. The selection of the channel (or drive A vs. B) is made by a twist in the floppy cable. Straight through wiring specifies floppy drive B whereas the split and twisted end of the cable designates the A: drive. Often, I have been personally annoyed by the ribbon mess in the case and rewired my own cables. Believe me, doing this is a mess, particularly with the twist and the split enz.

A much easier solution is to cut off the cable (any kitchen scissors will do) right behind the first 3 ½ inch connector and then run a straight through ribbon to the floppy drive itself. The drive will, of course, show up as B: drive in the BIOS and operating system, however, Swap Floppy Drive will allow to reset it as A: drive, not only in the operating system, but also as bootable device.

The only drawback is the human forgetfulness. If you ever have to clear the CMOS, this setting will also be erased and if you forget to enable it again, you will see the puzzling floppy drive error 40 message on boot up which will not allow you to access the a drive for booting.

Boot-Up Floppy Seek (disabled)

Some older floppy drives have only 40 tracks (360 / 720 kBytes) whereas the new drives have 80 tracks (1.44 / 2.88 MBytes). Enabled means that the system will perform a check on whether the 40 or 80 track type drive is installed in the system, regardless of whether a disk is in the drive. In order to increase the life span of any floppy drive, this setting should be disabled.

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