SCSI

In this video from ITFreeTraining, I will look at the Small Computer System Interface or SCSI. SCSI has been around since the 80’s, however it is being replaced by other standards like SAS which I will look at later in the video. Although SCSI is not used in new computers nowadays, it is important to have a basic understanding of it if you are repairing old equipment.
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SCSI
0:22 SCSI stands for Small Computer System Interface. As the name suggests, it is an interface designed to connect devices to a computer. SCSI has different levels of success in the marketplace and is fundamentally used to connect hard disk drives to computers. However, it could also be used to connect other devices to computers, like optical drives and scanners.
Computers sold on the market today no longer use the SCSI interface. Later in the video, I will look at how SCSI has changed and where you may encounter it today. For the exam, it is good to have an understanding of how SCSI is used today. For the technician, it is good to have a basic understanding, in case you have to fix an old computer that still uses SCSI. To start with, I will have a look at how SCSI works, so you can understand why it was used in the marketplace.
Parallel
1:10 The SCSI interface uses parallel technology. So essentially this means that multiple bits are transferred at once in sync with each other. You may be thinking that there were a lot of other interfaces that also transferred data in parallel, so what made SCSI different?
SCSI generally transferred data faster than its competitors. Although there are many different versions of SCSI which have different speeds, let’s consider an example of what sorts of speeds we are looking at, compared with a competitor.
Back in the 90’s, SCSI was transferring data at 320 Mega Bits per second whereas IDE was transferring at 133 Mega Bits per second. There were different versions of each which ran at different speeds, however this will give you an idea what speeds were available at the time. The main take away is that SCSI ran faster than the competing products. This extra speed cost more money to implement, and thus SCSI devices cost more than their competitors.
Due to the higher cost, SCSI devices tended to be used on high-end workstations and servers. Some manufacturers like Apple used them for a while. Essentially, in the old days, if you wanted more performance you would get SCSI; however, you would pay more for it.
SCSI Connectors
2:26 There were many different versions of SCSI over the years. Each version of SCSI offered increased speed, and with the different versions came many different connectors. You can see some of the connectors that SCSI uses. There are too many to go through and there is not much point learning them since SCSI is not used in new computers any more. If you are fixing a computer and see a connector like one of those shown, you are probably working with SCSI.
It is unlikely that you will get tested on the old SCSI technology in the exam, but I will go through some basic things so you will have an idea how to support it if you come across it.
Description to long for CZcams. Please see the following link for the rest of the description. itfreetraining.com/ap/1c45
References
“The Official CompTIA A+ Core Study Guide (Exam 220-1001)” Chapter 3 Position 11012-11292
“CompTIA A+ Certification exam guide. Tenth edition” Page 303
“Picture: External SCSI Connectors” www.scsi4me.com/scsi-connector...
“Picture: Picture of rear of SCSI device” en.wikipedia.org/wiki/File:Sc...
“Picture: SCSI terminator ” commons.wikimedia.org/wiki/Fi...
“SCSI (Small Computer System Interface)” www.linktionary.com/s/scsi.html
“Picture: SAS Connector” commons.wikimedia.org/wiki/Fi...
Credits
Trainer: Austin Mason ITFreeTraining.com
Voice Talent: HP Lewis hplewis.com
Quality Assurance: Brett Batson www.pbb-proofreading.uk