Weekly Tweaks Archive V

Current CPU Temperature
Indicates current CPU temperature if you have a monitoring system. Bear in mind, though, that the CPU is not working hard while you are in the BIOS setup.

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Pentium IV
Uses NetBurst micro-architecture, and SSE2 (Streaming SIMD Extensions 2), but will need special software to use them properly. It uses clock rates of 1.4 Ghz or higher, with no upper limit as yet, with a 400 MHz Front Side Bus, which is three times faster than the Pentium III's (133 MHz) and twice as fast as the Athlon's, just to put it in perspective. These speed increases are best seen with applications that are disk- and screen-intensive, however. Although Intel's idea is to use RDRAM with it, through its 850 chip set, you can expect to see other chipsets that support different memory. AMD's answer is a variation of the Athlon, called the Mustang.

AMD
The Athlon, or K7, uses Slot A (now Socket A) technology and has three super-scalar fully pipelined execution units for floating point, with allowance for MMX and 3DNow! instructions, together with 128K of L1 cache and 512K of half-speed off-chip L2 cache (on earlier models) with its own special bus. Later models have 256K of L2 cache on-chip, so expect to see a total of 384K. The L1 is four times larger than that on the PIII, and the Athlon can decode any three x86 instructions at a time, where as the PIII can only do this if two of the three are simple and relate to a single internal operation. It can also send up to nine internal instructions per clock cycle compared to the PIII's five. A variation called the Mustang is AMD's answer to the Pentium IV.

The system bus (between CPU and system logic) also runs at 200 MHz (266 for the Mustang), being developed from the EV6 bus used with the DEC Alpha, so a new chipset is required, supplied by AMD initially. A side benefit of using this bus is that multiprocessor chipsets for the Alpha 21264 will also support the Athlon. Slot A looks like Slot 1, but the pinouts are different, partly for copyright reasons and partly because AMD felt it was time to blaze new trails. The result is a bus design that is technically superior.

The release of Socket A makes Slot A redundant, but newer Athlons will be released in limited numbers for Slot A, though you should use them with AMD chipsets, because the 750 chipset was designed for future processors. There will, no doubt, be plenty of slocket converters available. The Duron uses Socket A as well, and a 200 MHz Front Side Bus, against the Celeron's 66 MHz. Its 192K of cache (128K L1 and 64K L2) certainly helps it give the PIII a run for its money.

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WAIS
Wide Area Information Server. A way of searching huge distributed database servers over the Internet, but any network will do. Think of gopher as a table of contents, and WAIS as an index.

WAN
Wide Area Network. A network operating over long distances, with a third party involved in its operation, such as the telephone company. A network spread over a large campus, but operated internally may be over a wide area, but is still technically a Local Area Network.


WASHITO
Wait And See How It Turns Out.


Wavelength Multiplexing
Used in fibre, where more than one wavelength of light is used to multiplex signal on to a fibre.

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Byte Merging
This exists where multiple writes to non-contiguous memory addresses are merged into one PCI-to-memory operation by the host controller, letting devices sort out the ones they want, which increases bus throughput and hence performance for devices that support it-not all PCI video cards do, so enable this unless you get bad graphics (this setting is intended to improve video performance). When enabled, the controller checks the CPU Byte Enable signals (8 of them) to see if data from the PCI bus can be merged. See also Byte Merge Support (next) and CPU-PCI Byte Merge.

Byte Merge Support
In this case, enabling means that CPU-PCI writes are buffered (Award). 8- or 16-bit data moving between the CPU and PCI bus is accumulated, or merged, into 32-bit chunks and held in a buffer, being written to the PCI bus when time permits.

CPU to PCI Byte Merge
Consecutive 8- or 16-bit writes in the same double-word address en route from the CPU to the PCI bus are held in a posted write buffer, from where they are sent as a single double-word, giving faster video performance, as byte merging is performed in the compatible VGA range only (0A0000-0BFFFFh).
-Enabled is best.

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Speed Model
For BIOSes that auto detect the CPU. Speedeasy does it for you. Jumper emulation is for the settings as taken from the manual, in terms of bus clock, multiplier, voltage and CPU speed.

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The link between the CPU and Northbridge is called Front-side bus, which is (usually) the same speed as the Memory Bus, and can be varied, as when overclocking. The Back-side bus connects the CPU with L2 cache. But even this is changing, because the essential problems that plagued the original PC still haven’t gone away, in that some parts of the machine simply run too slowly, notably the PCI bus, which, at 33 MHz, is 10 times slower than even a 333 MHz CPU. 

If that weren’t bad enough, all the I/O, including USB and Firewire, go through the Southbridge and hence the PCI bus, losing all that speed advantage. Intel's intention (starting with 800 series chipsets) is to have three major components, namely a memory controller hub, an I/O controller hub and a firmware hub, all tied together with a 266 Mbps interface. The CPU and AGP would talk directly to the memory controller, and any ISA slots would run through the firmware hub.

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AGP Fast Write Transaction

As an addition to the last newsletter's mention of AGP, this is an optional feature that allows data to be sent directly from the corelogic (i.e. chipset) to the AGP master (graphics chip) instead of keeping a copy in system memory and making the AGP master fetch it. Enabled is best for performance.

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Soft-off by PWR-BTTN

Instant-Off allows the system to switch off immediately the power button is pressed. Otherwise, it will only do so after you press it for more than 4 seconds. Below this, the switch acts as a suspend button, leaving a small amount of power on the system so that power can be restored not only by the power switch but also by ring detection-your PC is therefore potentially subject to voltage surges on the power line 24 hours a day, whereas a conventional power switch physically disconnects the PC. This option may also leave power on the parallel ports and prevent printers from entering their own power saving modes.

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