The capacity of the Williams tube was a few hundred to around a thousand bits, but it was much smaller, faster, and more power-efficient than using individual vacuum tube latches. Since the electron beam of the CRT could read and write the spots on the tube in any order, memory was random access. It stored data as electrically charged spots on the face of a cathode-ray tube. The first practical form of random-access memory was the Williams tube starting in 1947. Such registers were relatively large and too costly to use for large amounts of data generally only a few dozen or few hundred bits of such memory could be provided. Latches built out of vacuum tube triodes, and later, out of discrete transistors, were used for smaller and faster memories such as registers. Drum memory could be expanded at relatively low cost but efficient retrieval of memory items required knowledge of the physical layout of the drum to optimize speed.
#Ran world gs retrieving data serial
Ultrasonic delay lines were serial devices which could only reproduce data in the order it was written. Synchronous dynamic random-access memory (SDRAM) later debuted with the Samsung KM48SL2000 chip in 1992.ġ- megabit (Mbit) chip, one of the last models developed by VEB Carl Zeiss Jena in 1989Įarly computers used relays, mechanical counters or delay lines for main memory functions. The first commercial DRAM IC chip, the Intel 1103, was introduced in October 1970. Commercial MOS memory, based on MOS transistors, was developed in the late 1960s, and has since been the basis for all commercial semiconductor memory. Commercial uses of semiconductor RAM date back to 1965, when IBM introduced the SP95 SRAM chip for their System/360 Model 95 computer, and Toshiba used DRAM memory cells for its Toscal BC-1411 electronic calculator, both based on bipolar transistors.
The two main types of volatile random-access semiconductor memory are static random-access memory (SRAM) and dynamic random-access memory (DRAM). These include most types of ROM and a type of flash memory called NOR-Flash.
Other types of non-volatile memories exist that allow random access for read operations, but either do not allow write operations or have other kinds of limitations on them. RAM is normally associated with volatile types of memory (such as dynamic random-access memory (DRAM) modules), where stored information is lost if power is removed, although non-volatile RAM has also been developed. In today's technology, random-access memory takes the form of integrated circuit (IC) chips with MOS (metal-oxide-semiconductor) memory cells. Usually more than one bit of storage is accessed by the same address, and RAM devices often have multiple data lines and are said to be "8-bit" or "16-bit", etc. RAM contains multiplexing and demultiplexing circuitry, to connect the data lines to the addressed storage for reading or writing the entry. A random-access memory device allows data items to be read or written in almost the same amount of time irrespective of the physical location of data inside the memory, in contrast with other direct-access data storage media (such as hard disks, CD-RWs, DVD-RWs and the older magnetic tapes and drum memory), where the time required to read and write data items varies significantly depending on their physical locations on the recording medium, due to mechanical limitations such as media rotation speeds and arm movement. Plotly choropleth map.Random-access memory ( RAM / r æ m/) is a form of computer memory that can be read and changed in any order, typically used to store working data and machine code.
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