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Semiconductor Memory Circuits
Published in Vojin G. Oklobdzija, Digital Design and Fabrication, 2017
Access patterns: On the basis of the order in which data can be accessed, memories can be classified into two different categories: RAMs and non-RAMs. Most memories belong to the random access class. In RAMs, information can be stored or retrieved in a random order at a fixed rate, independent of physical location. There are two kinds of RAMs: static random access memories (SRAMs) and dynamic random access memories (DRAMs). In SRAMs, data is stored in a latch and it retains the data written on the cell as long as the power supply to the memory is retained. In DRAMs, the data is stored in a capacitance as electric charge and the written data needs to be periodically refreshed to compensate for the charge leakage of the capacitance. It should be noted that both SRAM and DRAM are volatile memories, i.e., they lose the written information as soon as the power supply is turned OFF.
Microcontroller Hardware
Published in Syed R. Rizvi, Microcontroller Programming, 2016
RAM stands for Random Access Memory and is often referred to as read/write memory. The RAM is a general-purpose volatile type of memory, where the information (data or programs) is lost after the power is switched off. By default, the HC11E9 RAM is located at $0000–$01FF of the memory map. To achieve the flexibility with on-chip and off-chip resources, the user is given the ability to relocate the RAM in the memory map by altering the RAM map position control bits in the INIT register. Figure 3.19 shows the structure of the 8-bit INIT register where the four bits, such as RAM3, RAM2, RAM1, and RAM0 specify the most significant hex digit of the 16-bit RAM address in the memory map. As shown in Table 3.7, the location of RAM can be moved to the start of any 4K memory block. Recall that the HC11 uses a 16-bit address. Therefore, since 4 bits are already used, only 12 bits of the 16-bit address remain to be used. The maximum number of memory locations that can be addressed with the remaining 12 bit is 212 = 4K. Before we move on to the next type of memory in HC11, let us take an example to see how the RAM mapping can be changed using the INIT register.
Making Sounds with Digital Electronics
Published in Russ Martin, Sound Synthesis and Sampling, 2012
The storage that is used to hold the samples as they are made or replayed is normally fast read–write memory called RAM. RAM is an acronym for random-access memory, and the name refers to the ability to rapidly access any location in the memory device at random. In contrast, a tape recorder is much more restricted in its access it either plays back the audio, or it requires to be wound or rewound to reach an alternative location on the tape. RAM storage does not have this problem any location can be accessed as quickly as any other. RAM storage comes in two forms: static and dynamic. Static RAM chips will hold their contents for as long as they are powered up, which makes them ideal for short-term storage using battery backup. Dynamic RAM chips lose their contents if they are not continuously ‘refreshed’ by the host microprocessor chip. Dynamic RAM chips are considerably cheaper than the static version, and therefore low-cost samplers are more likely to have dynamic RAM that will require backing up to another more permanent type of storage before powering down the sampler.
Node Voltage and KCL Model-Based Low Leakage Volatile and Non-Volatile 7T SRAM Cells
Published in IETE Journal of Research, 2022
C. S. Hemanth Kumar, B. S. Kariyappa
In recent days because of faster growth and more significance of portable handheld electronic devices, such as smart watches, cellphones, PDAs, etc., need energy-efficient hardware. Random Access Memory (RAM) Chips are used in every electronic device essential for daily life.