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RAS only refresh – In this mode the address of the row to refresh is provided by the address bus lines typically generated by external counters in the memory controller. CAS before RAS refresh (CBR) – In this mode the on-chip counter keeps track of the row to be refreshed and the external circuit merely initiates the refresh cycles. [5]
A memory controller, also known as memory chip controller (MCC) or a memory controller unit (MCU), is a digital circuit that manages the flow of data going to and from a computer's main memory. [ 1 ] [ 2 ] When a memory controller is integrated into another chip, such as an integral part of a microprocessor , it is usually called an integrated ...
The ZX8301 [1] [2] is an Uncommitted Logic Array (ULA) integrated circuit designed for the Sinclair QL microcomputer.Also known as the "Master Chip", it provides a Video Display Generator, the division of a 15 MHz crystal to provide the 7.5 MHz system clock, ZX8302 register address decoder, DRAM refresh and bus controller.
SDRAM designed for battery-powered devices offers some additional power-saving options. One is temperature-dependent refresh; an on-chip temperature sensor reduces the refresh rate at lower temperatures, rather than always running it at the worst-case rate. Another is selective refresh, which limits self-refresh to a portion of the DRAM array.
Circuit board design: [52] New power supplies (VDD/VDDQ at 1.2 V and wordline boost, known as VPP, at 2.5 V); VrefDQ must be supplied internal to the DRAM while VrefCA is supplied externally from the board; DQ pins terminate high using pseudo-open-drain I/O (this differs from the CA pins in DDR3 which are center-tapped to VTT). [52]
Perhaps a key to the initial success of the Z80 was the built-in DRAM refresh, at least in markets such as CP/M and other office and home computers. (Most Z80 embedded systems use static RAM that do not need refresh.) It may also have been its minimalistic two-level interrupt system, or conversely, its general multi-level daisy-chain interrupt ...
SRAM offers a simple data access model and does not require a refresh circuit. Performance and reliability are good and power consumption is low when idle. [11] Since SRAM requires more transistors per bit to implement, it is less dense and more expensive than DRAM and also has a higher power consumption during read or write access. The power ...
A single read or write operation for the DDR4 SDRAM consists of a single 8n-bit-wide 4-clock data transfer at the internal DRAM core and 8 corresponding n-bit-wide half-clock-cycle data transfers at the I/O pins. [20] RDRAM was a particularly expensive alternative to DDR SDRAM, and most manufacturers dropped its support from their chipsets ...