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Manufacture of batteries and accumulators Directive 2006/66/EC of the European Parliament and of the Council of 6 September 2006 on batteries and accumulators and waste batteries and accumulators and repealing Directive 91/157/EEC, commonly known as the Battery Directive, regulates the manufacture and disposal of batteries in the European Union with the aim of "improving the environmental performance of batteries and accumulators". In the 1980s, batteries commonly contained hazardous elements such as mercury, cadmium, and lead, which when incinerated or landfilled, presented a risk to the environment and human health. Directive 91/157/EEC was adopted on 18 March 1991 to reduce these hazards by harmonizing Member States’ laws on the disposal and recycling of batteries containing dangerous substances. Directive 2006/66/EC repealed Directive 91/157/EEC and sets maximum quantities for certain chemicals and metals in batteries; tasks Member States with encouraging improvements to the environmental performance of batteries; requires proper waste management of these batteries, including recycling, collections, "take-back" programs, and disposal; sets waste battery collection rates; sets financial responsibility for programs; and makes rules covering most phases of this legislation, including labeling, marking, documentation, reviews, and other administrative and procedural matters

 

In a computer’s central processing unit (CPU), an accumulator is a register in which intermediate arithmetic and logic results are stored. Without a register like an accumulator, it would be necessary to write the result of each calculation (addition, multiplication, shift, etc.) to main memory, perhaps only to be read right back again for use in the next operation. Access to main memory is slower than access to a register like the accumulator because the technology used for the large main memory is slower (but cheaper) than that used for a register.

The canonical example for accumulator use is summing a list of numbers. The accumulator is initially set to zero, then each number in turn is added to the value in the accumulator. Only when all numbers have been added is the result held in the accumulator written to main memory or to another, non-accumulator, CPU register.

An accumulator machine, also called a 1-operand machine, or a CPU with accumulator-based architecture, is a kind of CPU in which—although it may have several registers—the CPU always stores the results of most calculations in one special register—typically called "the" accumulator of that CPU. Historically almost all early computers were accumulator machines; and many microcontrollers still popular as of 2010 (such as the 68HC12, the PICmicro, the 8051 and several others) are basically accumulator machines.

Modern CPUs are typically 2-operand or 3-operand machines—the additional operands specify which one of many general purpose registers (also called "general purpose accumulators") are used as the source and destination for calculations. These CPUs are not considered "accumulator machines".

The characteristic which distinguishes one register as being the accumulator of a computer architecture is that the accumulator (if the architecture were to have one) would be used as an implicit operand for arithmetic instructions. For instance, a CPU might have an instruction like:

 

From Wikipedia, the free encyclopedia : Manufacture of batteries and accumulators