According to experts from the Standards and Standards Technology Co., Ltd., Norway is not a member of the European Community and the European Union. Its requirements for environmental protection are different from those of the EU, and even more stringent than the EU. Although this regulation applies only to Norway, it may become a de facto RoHS standard for the use of electrical and electronic products exported to Europe, as few companies will exclusively produce a targeted product for a market separately, unless Do not intend to sell the products to Norway. The two regulations are different in the following ways:
First of all, the two seem to be different. The PoHS name looks similar to the EU RoHS Directive, but the two are very different. First limit the range of products containing hazardous substances. Norwegian PoHS regulations cover a wider range of products than RoHS. Because it is a regulation on consumer products, PoHS covers all consumer products except food, food packaging, fertilizers, medical equipment, tobacco, transportation and ancillary equipment. It includes product categories in addition to electrical and electronic consumer goods, including clothing, luggage, construction, toys and so on. RoHS only includes electrical and electronic equipment and component electrical components.
Second, the types of substances that are restricted are different. There are 18 types of substances restricted by the PoHS regulations, and the EU RoHS Directive restricts six types of substances: lead, mercury, cadmium, hexavalent chromium, polybrominated biphenyls and polybrominated diphenyl ethers. There are two types of PoHS regulations - lead and cadmium are included in the RoHS Directive, and 16 substances are prohibited from being used.
Again, the restricted substance concentration is different. The PoHS regulations are more restrictive than the EU RoHS Directive on hazardous substances. For lead limit requirements, the EU RoHS Directive requires a lead limit concentration of 0.1% (1000 ppm), while the PoHS regulations require a lead limit concentration of 0.01% (100 ppm).
Fourth, the PoHS regulations also have a list of exemptions, but the exempt list is different from the EU RoHS. In addition, the monitoring and control equipment excluded by the EU RoHS is not excluded in the Norwegian PoHS and needs to be met. The PoHS regulations comply with most of the previously existing rules, including the battery and battery directives and packaging directives already in the EU RoHS. This means that electrical and electronic products within the EU RoHS Directive do not need to meet more stringent lead content requirements, but they must meet the requirements for the use of 16 substances that are not required by RoHS. As can be seen from the above, PoHS requirements are more stringent than RoHS.
Small computer system interface (SCSI) is an independent processor standard for system level interfaces between computers and intelligent devices (hard disks, floppy drives, optical drives, printers, scanners, etc.). SCSI is an intelligent universal interface standard.
The maximum synchronous transmission rate of the original SCSI standard was 5MB / S (scsi-1, also known as narrowscsi, in 1986, the maximum support for seven devices, the clock frequency was 5MHz), and the later SCSI II specified two options for increasing the speed. One is to increase the frequency of data transmission, namely fast SCSI (in 1994, the maximum support for 7 devices) is 10 Mb / S (10 MHz) because the frequency is doubled; the other is to double the transmission frequency and increase the width of the data path from 8 bits to 16 bits. The maximum synchronous transmission speed of widescsi is 20MB / S (the clock frequency is 10MHz, in 1996, the maximum support for 15 devices).
The third generation of SCSI appeared around 1995, but there was no unified standard
1. Ultra SCSI with maximum synchronous transmission speed of 20MB / S (also known as FAST-20 SCSI, clock frequency of 20MHz);
2. Ultra wide SCSI with maximum synchronous transmission speed of 40MB / S (same as 1);
3. Ultra2 SCSI with maximum synchronous transmission speed of 40MB / S (also known as fast-40 SCSI, clock frequency of 40MHz, 1997).
Later, some newer SCSI standards appeared
1. Ultra2 widescsi with maxmum synchronous transmission speed of 80mb / S (clock frequency of 40MHz);
2. Ultra 3 SCSI with maximum synchronous transmission speed of 160MB / S (also known as ultra-160 or fast-80 wide SCSI, clock frequency of 40MHz plus double data rate, 1999);
3. Ultra 320 SCSI with maximum synchronous transmission speed of 320mb / S (also known as ultra 4 SCSI, clock frequency of 80MHz plus double data rate, 2002); 4. Ultra 640 SCSI with maximum synchronous transmission speed of 640MB / S (clock frequency of 160MHz plus double data rate, 2003, is the latest SCSI standard)
This interface is a convenient interface standard for system integration, cost reduction and efficiency improvement. More and more devices will use the SCSI interface standard. Therefore, there are many hard disks and SCSI CD-ROM drives with SCSI interface. However, due to the cost problem, they are mainly used on medium and high-end servers and workstations.
Metal Male SCSI Cover Section
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