need a complete solution

hi all of us know that the hard disk store memory as a charge in its cylinder

but how about ram ???
can anybody tell me how memory is stored in a ram ??

please tell me also about the various rams available and their functionality

please help me know about these things

thanks in advance

vishnu.eda said:

hi all of us know that the hard disk store memory as a charge in its cylinder

Click to expand...

Who gave u that idea? There is no charge stored in any cylinder, but a magnetic domain on a disk.

Anyway, a static ram stores data using flip-flops, while a dynamic ram stores using a capacitor and a transistor.

SRAM memory uses SR latch as a memory unit... That is just two inverters connected in a positive feedback...

The two switches are used to sellect the cell...
There are two basic SRAM cells that I know about, 6 transistor (6T) and 4 transistor (4T) SRAM... Their only diference is in inverters... 6T uses classic CMOS inverter, but 4T uses pasive resistance as pull up... BL are bit lines... As you see you have BL and its inverted line notBL, that is very usefull sometimes...

For DRAM there are also two basic types, 1T and 3T... 1T uses capacitor as a memory unit, and 3T uses transistor as capacitor... It is called dynamic because you need to refresh it periodically, because capacitor can discharge and you could lose information of what is stored, at SRAM you do not have to refresh memory...




I sugest you to read Rabaey, there is a lots of info there...



And there is no charge in hard drive, it is magnetic memory... Something like old cassetes, but much much better....