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Not synchronized. Communication without any timing mechanism. Instead of a timing mechanism you have communication rules. There is a start bit and a stop bit to notify the other end when communication starts and stops.

Pros: If one computer needs to send data then it can do so without having to keep stopping during each clock cycle.
Cons: With the use of start and stop bits you have 20% overhead. In other words, if you send 100 KB of information then it takes 120 KB to get it all there.



In this setup, data is sent as strict blocks of information. Because the timing is uniform, there is no need for a start and stop bit.

Pros: No need for extra information.
Cons: There is timing so you could say that there are blank spaces.



Stands for Interrupt ReQuest. This is how a peripheral tells the CPU it needs its attention. There are specific numbers to tell the CPU which peripheral needs time and the priority. The priority is determined from least to greatest (i.e. 0 is the most important and 15 is the least). Most systems have 16 of these IRQs. Some older systems only have 9. This used to limit the numbers of things you can put in a system. Now technology has advanced so there is now IRQ sharing, but be mindful when working with ISA cards and older systems as you can run out fast.


Male vs. Female Connector

A male connector is the side of a connection that has the prongs--like the power plug on your computer monitor. The side that goes from your monitor into the wall is the male. The outlet is the female side of the connector.



This term you will see in the context of DB-25 or DB-9. What this is describing is the shape of the connector. The connector has a definite shape like a capital D (also could be called a trapezoid with rounded angles).