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80186 Microprocessors: Introduction and Architecture

Hello friends, today we are going to discuss the 80186 microprocessor with integrated peripherals. The Intel 80186 is an improved version of the 8086 microprocessor. 80186 is a 16-bit microprocessor with a 16-bit data bus and a 20-bit address bus. It has a programmable peripheral device integrated into the same package. The instruction set of the 80186 is a superset of the instruction set of the 8086. The term super-set means that all of the 8086 instructions will execute properly on an 80186, but the 80186 has a few additional instructions. The following figure shows the block diagram and pin diagram of 80186. The CPU is divided into seven independent functional parts. 80186 internal block diagram  80186 68-pins pin diagram  Functional parts of 80186 Microprocessor The Bus Interface Unit (BIU) Execution Unit (EU) Clock Generator Programmable interrupt controller Programmable Chip Select Unit (CSU) Programmable DMA Unit Programmable counter/timers The Bus Interface Unit
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Coaxial Cable

Hello friends. today we are going to see the another Common transmission medium the coaxial cable. Coaxial cable, commonly called as coax is a type of copper cable. It has better shielding than twisted pairs. 

Structure of Coaxial Cable

Coaxial cable consists of a stiff copper wire surrounded by an insulating material. The insulator is encased by a braided mesh cylindrical conductor. The outer conductor is covered in a protective plastic sheath. Coaxial cable gives a good combination of high bandwidth and excellent noise immunity. The bandwidth is depends on cable length. E.g. 1km cables, data rate of 1 to 2 Gbps.
This cable is commonly used in telephone system, cable television and some LAN.
Coaxial cable
coaxial Cable

Types of Coaxial cable

Coaxial cable is commonly used in two types depending on their impedance and ohms. Impedance is the amount of resistance the waves proceeding through the coaxial cable. The lower the impedance, the more easily the waves flow through the cable. Standard coax impedances are 50-75 ohms. This has been tasted as a great balance between power handling a low loss. These  two types are as follows.

Baseband coaxial cable

50-ohm cable, called baseband coaxial cable, is commonly used for digital transmission. It transmit a single signal at a time with very high speed. The transmission of digital signal on the cable is bidirectional. For 1Km distance, baseband cables bandwidth is 1-2 Gbps but for longer distance, cable can used with low data rates or use amplifier to increase the power of signals.

Broadband coaxial cable

Another 75-ohm cable, called broadband coaxial cable, is commonly used for analog transmission on standard cable television cabling.


Broadband networks (a) Dual cable, (b) Single cable.
Broadband systems typically cover a large area and therefore need analog amplifiers to strengthen the signal. These amplifiers can only transmit signals in one direction, so a computer outputting a packet will not be able to reach computers upstream from it if an amplifier lies between them. To solve this problem, two types of broadband systems have been developed: Dual cable and single cable systems.
Dual cable systems have two identical cables running in parallel. The root of the cable tree is head-end. All computers transmit data on cable 1 and receive data on cable 2.
Single cable system allocates different frequency bands for inbound and outbound communication on a single cable. The low frequency band is used for communication from the computers to the head-end, which then shifts the signal to the high-frequency band and rebroadcast it. for inbound traffic, 5 to 30 MHz frequencies are used, and for outbound traffic, 40 to 300 MHz frequencies are used.
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