Memory

System memory

 There are some type of memory  in system.

1.physical. 2.logical. 3.virtual 4.flash. 5.cache.

Logical- It use large data store in a main memory.It enable to o.s. that arrange  the main memory in logical manner.logical manner means the location of main memory

It execute by some application program.

classification of memory

e .

when mapping time logical  address can be mapped in different location of main memory.

Main memory is divided in three section 1. conventional 2. Upper 3. extended 4. virtual

conventional- It use from Dos & it use 640 k.b.  space of dos. the other programe of IT'S 

lotus , word star .It is also base memory  we can say that.

Upper- It use 640 k.b. to 1 m.b. space so there is  more empty space in memory so this memory use by .306 processor.

Extended- It use upper amount rather than 1

m.b. . it does not use from dos & dos user does not know that how to use of It. It only use in o.s. 

Virtual memory- It is a part of hard disk.It has a set of address of memory & store data

& instruction  it convert virtual address to real memory address. IT's main work to increase the memory address.(os) divided the virtual memory into page.& each page

contain the number of memory address.

so when processor have to need execute to other instruction so the o.s. copies all pages 

into real memory . so converting these process like these page converting process is 

called paging & swapping & virtual address

is convert into real address is called 

mapping.

वर्चुअल मेमोरी- यह हार्ड डिस्क का एक हिस्सा है। इसमें मेमोरी और स्टोर डेटा के पते का एक सेट होता है

 और निर्देश यह आभासी पते को वास्तविक स्मृति पते में परिवर्तित करता है।  मेमोरी एड्रेस को बढ़ाने के लिए आईटी का मुख्य कार्य। (ओएस) ने वर्चुअल मेमोरी को पेज में विभाजित किया है। प्रत्येक पेज

 मेमोरी एड्रेस की संख्या शामिल करें।

 इसलिए जब प्रोसेसर को अन्य निर्देशों को निष्पादित करने की आवश्यकता होती है तो o.s.  सभी पेज कॉपी करता है

 वास्तविक स्मृति में।  इसलिए इन प्रक्रियाओं को इन पेजों की तरह परिवर्तित करना कनवर्टिंग प्रक्रिया है पेजिंग और स्वैपिंग और वर्चुअल एड्रेस कहा जाता है

वास्तविक पते में परिवर्तित किया जाता है, मानचित्रण कहलाता है।

Flash memory- It is nonvolatile memory .

& it read & write data very faster. It write data in blocks  not in byte. It is electrically

 reprogrammable so the block size is 256 to 1 m.b. It removes the hard disk in portable p.c..so it installed on card . that is installed on pcmia card. (bios chip) is flash memory.

cache memory- It is placed between the ram 

& (c.p.u. ).it is smaller c.p.u. first seek  cache

if there is need of execution if required data 

getting than ok other wise c.p.u. seeking needful data in to ram.

cache level - There is two level of the cache

 memory. (l1, l2).

(l1 cache memory)- It is situated in c.p.u. area .it is called internal cache & primary cache  & it's size is 8 kb. to 64 kb.

( l2 cache memory) - It is situated in external area of cache so it is called external cache & secondary memory it's size 64kb to 2 mb.