How ROM(Read Only Memory) works, The way ROM works is by etching data on a piece of silicon. There are multiple types of ROM these include ROM(Read Only Memory) PROM(Programmable Read Only Memory), EPROM(Erasable Read Only Memory),and EEPROM(Electrical Erasable Programmable Read Only Memory). There are a few others that are based on the list above these include EAROM (Electrically Alterable Read Only Memory) this type of memory writes one bit of information at a time. Another alteration of ROM is a type of memory that is in almost every device made today is flash memory, developed in 1984 it is based off of EEPROM. Most ROMS can only write at speeds of up 15MB/s not including EAROM which as mentioned above only writes at 1bit/s.
ROM standard ROM not any variations can only be written once usually at the manufacturer. PROM can only be rewritten once as it uses high voltage to destroy and create permanent connections. EPROM can be rewritten up to 1000 times in a process in which the the chip is exposed to UV light for about 10 minutes and then reprogrammed using increasingly higher voltage the more times the chip is reprogrammed. EEPROM uses a similar semiconductor composition to EPROM but is fully capable of being reprogrammed from inside of the computer(or other electronic device that contains one) EEPROM flashing or writing is considerably slower than reading standard ROM or writing to RAM(Random Access Memory) as it take about a millisecond per bit on EEPROM and it only takes a nano second per bit on ROM or RAM.
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RAM
RAM(Random Access Memory) is a type of volatile memory used to cache memory for the CPU. RAM is a main functioning part of a computer, it is one of the four main components need to build a computer these include: Motherboard, HDD(Hard Disk Drive), CPU(Central Processing Unit), and RAM. The first viable random access array was The Williams Tube, it was a cathode ray tube which stored binary data it was capable of storing up to 1024 bits of data and did not have to look up the data in a sequential manner, most of the memory they were using at the time was tube relays which could only recall data in the order in which it was written. Then came drum memory which unlike the tube relays could be expanded for lower costs but still could only reproduce data in the order it was written.
Magnetic core memory was then invented in 1947 around the same time the williams tube, but was continually up until the mid 1970s and was the predominant memory for almost 20 years. It used magnetic rings to record data by changing the field and polarity of the rings and since the rings were each individually connected with their own wires the data could be accessed randomly. But in 1968 Robert H. Dennard invented Dynamic Random Access Memory also known as DRAM it would become the current standard for general use. There is another variant of RAM called S-RAM or Static Random Access Memory it works by keeping the data in a state of flip-flop, it is more expensive to produce but is faster and consumes less power. DRAM works by a transistor and a capacitor that comprise a memory cell the capacitor hold a high charge for On/1 and a low charge for Off/0 with the transistor working as a switch allowing the controller to read the charge on the capacitor.
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RAM
