RS 232 C

The RS 232 C is a standard for serial data transfer.

It specifies standard for 25 signals & hand shake signals which are used between DCE & DTE. The voltage levels, maximum capacitance for there signal lines are also described in this standard.

The standard RS-232 C interface is usually provided in computers for serial data transfer. A voltage between -3 V & -15 V under load is used for high logic or mark.

A voltage between +3 V & +15 V under load is used for low logic or space.

The voltage levels are not TTL compatible.

Magnet-Optical Storage Media

There are used for erasable disks. MO system includes basic principles of both magnetic & optical storage systems.

MO systems write magnetically & read optically.

It has two standard forms : 5.25 inches & 3.5 inches.

Flip Flops

A device is said to be bi-stable if it has 2 stable elements.

A flip-flop is a bi-stable device. It has 2 stable stales. Its O/P remains either high or low.

The high stable state is called SET. The other stable state is called RESET.

It can store binary bit,rather 0 or 1. Thus, it has storing capability, i.e., memory.

Shift Registers

In a shift register, the flip-flops are connected in series.

The O/P of each flip-flop is connected to the I/P of the adjacent flip flop.

The contents of a shift register can be shifted within the registers without changing the order of the bits.

Data are shifted one position left or right at a time when 1 clock pulse is applied. Shift register are used for the temporary storage of data. They are suited for processing serial data; converting serial data to parallel data & vice versa.

Then are 4 types of shift registers.

(ii) Serial In – Serial Out

(iii) Serial In – Parallel Out

(iv) Parallel In – Serial Out

(v) Parallel In – Parallel Out