Imagine your computer equipment to be ComputerLand with a few counties/provinces like PC, Monitor, Printer, Scanner and Hub. The most important is PC-County, where life is centered around the CPU-Factory. The workforce of that factory is located in the nearby Software-Town. And PC-County features a modern harbor where ships called FloppyDisks, CD or DVD arrive with raw material for the CPU-Factory. Likewise, the ships would also return with material for further use in Cupboard-County. The harbor featured a huge warehouse (HDD), where most of the raw material and (semi)finished products from the factory ends up being stored.
Factory & Shops
Another asset of PC-County is a somewhat older train station (Super I/O chip) where trains arrive from the local mines (Keyboard and Mouse) and there are trains importing raw material (bits) from Scanner-county or exporting semi-finished merchandise (other bits) to Printer-County, where they are processed in dpi's and eventually printed paper. Next to this old station there was a new station (USB) that housed High Speed Trains that one hoped would improve traffic.
PC Country also hosts a brandnew airport (WLAN-Client) where products come and go from another airport called WLAN-Host, situated in Hub-County. At WLAN-Host typically trucks arrive by road from Router-County or directly from Modem-County.
The airport replaces a road-network called LAN which is still there, but no longer used.
Apart from the growing exports by plain, train and boat, the largest customer of the CPU-Factory still is the local 'Graphics' shop, where the inhabitants of the nearby Monitor-County come to shop for pixel-feed. Actually, 'local shop' may be a too modest name for the huge commercial activity employed. They boost their own fast-growing assembly-plant (Graphics processor) to elaborate the raw bits from the CPU-Factory into pixel-feed, using considerable 'DRAM' warehouses of their own.
In fact, the CPU-Factory glad was glad that this part of the production was now handled by the shops and they could concentrate on the core-business. This assembly-line at the shops boosted their production tremendously. Furthermore, it helped to solve the problem of containing the heat production during manufacturing and of course the energy problem related to running the millions of machines (transistors), the airconditioning (fan) , the main loading docks of the plant (chipset, with the Northbridge and Southbridge platforms), its smaller storage rooms on the factory ground (Cache-memory), the 'DRAM' warehouses at the edge of the county and the traffic of bits.
The main factory was growing at a neck-breaking pace. Only 20 years ago, they were producing 8 bit units at a maximum (clock)speed of 16 MHz. Now, the units were 4 or 8 times bigger (32 or 64 bits) and the speed had grown to around 3000 MHz (3 GHz). The factory grounds (Socket) had of course expanded to 4 or 5 times their original size, but still this wasn't enough. Over the years, they had miniaturized the machines until now they were built with thin materials of a mere 130 or even 90 nanometres (90-130 nm) and in 2006 they would be built with parts not bigger than 65 nm. The same goes for the trucks and the roads. The fastest road, now called AGP-8x, between the Northbridge loading platform and the shops, had now carry loads at ... Mbps (million bits per second). After that, the road called 'Front Side Bus'-also through the Northbridge loading platform-from the CPU to the DRAM warehouse-now could carry 800 Mbps. The road from the Southbridge to the HDD Warehouse (called ATA), albeit slower than the roads from the Northbridge, was also improved considerably. And even the harbor could handle its ships faster and the ships themselves were much faster. The old FloppyDisk ship could carry only 1.44 MB (Megabyte = ca. 8 million bits) whereas the newer vessels like CD or DVD could carry 700 resp. 4200 MB.
With the increase of production, the air conditioning plant had grown, the shops got their own air conditioning and there was even talk to put a separate air conditioning at the fastest loading-platform, The Northbridge. Needless to say, that the main power plant ('Power Supply') also grew bigger and bigger and that their energy bill went through the roof. PC-County had a power plant of 350 W with a full-load efficiency of 65 to 73%. But at part load (<50%) this efficiency could drop below 40%. To make things worse, the voltages of the power plant were OK for the airconditioning and some other devices, but it was too high for the CPU-factory itself.
To remedy this, they needed an extra power supply (transformer) called VRM (Voltage Regulator Module) that also had an efficiency no higher than that of the central power plant. In short, for each Watt that entered the CPU-factory, they often consumed 3 Watts of electricity.
Already in 1995 the people in PC-County started an energy conservation programme, called APM (Advanced Power Management). And they made Mr. BIOS responsible. Mr. BIOS is the local town caller who every morning woke the people, telling them the time from the real time clock (RTC) and placing road signs all over PC-County, telling people where to go. He lived in a special house (NVRAM/CMOS chip) with its own small power generator (battery). Because of his special role in PC-County, power management came to him naturally. He wouldn't just tell the time-of-day, but at times there was no supply of raw material from the local mines, the ships, boats and planes, he would also tell the people to take a break or even go home to sleep.
Most of the times this went OK, but especially the imports and export suffered some hick-ups. To remedy these complaints, factory designers decided to appoint a group of people at the Southbridge platform to take make serious work of power management.
They had the ability to slow down the machines when work was slow to speeds as low as 500 MHz or a mere 20% of the maximum. Instead of heating all the warehouses (Cache and DRAM) all of the time, they would just heat the parts where people worked. The would slow down traffic on the roads to match the reduced production speed, ordering also other counties, like e.g. Monitor-County etc.. to temporarily use less energy. Naturally air conditioning needs would also be reduced. Yet, when boats, ships or trains would arrive with batches of new raw material or when the Monitors placed a big order, they would have the factory up and running in no time.
With all this intelligence available, there were only a few things that could go wrong. The first question was what the future would bring: Would clock speeds go up, would units become bigger to feed the pixel-hungry people at Monitor-County, would airports be the new standard not only in ComputerLand but everywhere else, etc..
But the second question was in the present: The ACPI programme could be controlled by the president of ComputerLand. Its effect could be severely diminished by only one person: you.