Prior to the advent of stand-alone DSP chips discussed below, most DSP applications were implemented using bit-slice processors. The AMD 2901 bit-slice chip with its family of components was a very popular choice. There were reference designs from AMD, but very often the specifics of a particular design were application specific. These bit slice architectures would sometimes include a peripheral multiplier chip. Examples of these multipliers were a series from TRW including the TDC1008 and TDC1010, some of which included an accumulator, providing the requisite multiply–accumulate (MAC) function.
In 1978, Intel released the 2920 as an "analog signal processor". It had an on-chip ADC/DAC with an internal signal processor, but it didn't have a hardware multiplier and was not successful in the market. In 1979, AMI released the S2811. It was designed as a microprocessor peripheral, and it had to be initialized by the host. The S2811 was likewise not successful in the market.
In 1980 the first stand-alone, complete DSPs – the NEC µPD7720 and AT&T DSP1 – were presented at the International Solid-State Circuits Conference '80. Both processors were inspired by the research in PSTN telecommunications.
The Altamira DX-1 was another early DSP, utilizing quad integer pipelines with delayed branches and branch prediction.
The first DSP produced by Texas Instruments (TI), the TMS32010 presented in 1983, proved to be an even bigger success. It was based on the Harvard architecture, and so had separate instruction and data memory. It already had a special instruction set, with instructions like load-and-accumulate or multiply-and-accumulate. It could work on 16-bit numbers and needed 390 ns for a multiply–add operation. TI is now the market leader in general-purpose DSPs. Another successful design was the Motorola 56000.
About five years later, the second generation of DSPs began to spread. They had 3 memories for storing two operands simultaneously and included hardware to accelerate tight loops, they also had an addressing unit capable of loop-addressing. Some of them operated on 24-bit variables and a typical model only required about 21 ns for a MAC. Members of this generation were for example the AT&T DSP16A or the Motorola DSP56001.
The main improvement in the third generation was the appearance of application-specific units and instructions in the data path, or sometimes as coprocessors. These units allowed direct hardware acceleration of very specific but complex mathematical problems, like the Fourier-transform or matrix operations. Some chips, like the Motorola MC68356, even included more than one processor core to work in parallel. Other DSPs from 1995 are the TI TMS320C541 or the TMS 320C80.
The fourth generation is best characterized by the changes in the instruction set and the instruction encoding/decoding. SIMD extensions were added, VLIW and the superscalar architecture appeared. As always, the clock-speeds have increased, a 3 ns MAC now became possible.
Tuesday, February 21, 2012
Proccessor History
SAMSUNG ANNOUNCES GALAXY TAB 7.0 PLUS
Samsung today announces the latest addition to the Samsung Galaxy Tab Portfolio, the Galaxy Tab 7.0 Plus, which joins the Galaxy Tab 7.7, 8.9 and 10.1 devices to provide a range of exceptional Samsung tablets to choose from.
The newest member of Samsung’s Galaxy Tab range offers a portable, rich multimedia experience on a 7-inch WSVGA display with DivX multi codec support and weighs just 345g and measures 9.96mm. The Galaxy Tab 7.0 Plus’ size means it fits easily into an inside-jacket pocket or a handbag, making it an ideal device for those who want to stay productive and entertained while on the move.
The Galaxy Tab 7.0 Plus runs the latest Android Honeycomb 3.2 and delivers a smooth and intuitive user experience with a superior performance powered by 1.2GHz dual core processor. Web browsing is also enhanced by Adobe Flash and super-fast HSPA+ connectivity, providing download speeds up to three times faster than a conventional HSPA connection.
With additional features such as, full HD video capability and Social, Readers and Music Hub services – the Galaxy Tab 7.0 Plus is perfect for watching films, playing games, reading e-books or staying connected with email. It can also be used as a universal home entertainment remote control.
Simon Stanford, Managing Director, Mobile, Samsung UK and Ireland said: “The Galaxy Tab 7.0 Plus packs power and productivity into a lightweight design. The latest addition to Samsung’s Galaxy Tab range demonstrates our ongoing dedication to designing a variety of premium tablets and continued innovation to suit different needs and lifestyles. We are delighted to be able to introduce the Galaxy Tab 7.0 Plus to the Galaxy family in the UK later this year.”
The Samsung Galaxy Tab 7.0 Plus will be available in a range of UK retailers later this year. Read More...
Memory (Random acces Memory/RAM)
Random access memory (usually known by its acronym, RAM) is a form of computer data storage. Today it takes the form of integrated circuits that allows the stored data to be accessed in any order (i.e., at random). The word random thus refers to the fact that any piece of data can be returned in a constant time, regardless of its physical location and whether or not it is related to the previous piece of data.[1]
This contrasts with storage mechanisms such as tapes, magnetic discs and optical discs, which rely on the physical movement of the recording medium or a reading head. In these devices, the movement takes longer than the data transfer, and the retrieval time varies depending on the physical location of the next item.
The word RAM is mostly associated with volatile types of memory (such as DRAM memory modules), where the information is lost after the power is switched off. However, many other types of memory are RAM as well (i.e., Random Access Memory), including
most types of ROM and a kind of flash memory called NOR-Flash.
History
An early type of widespread writable random access memory was the magnetic core memory, developed from 1949 to 1952, and subsequently used in most computers up until the development of the static and dynamic integrated RAM circuits in the late 1960s and early 1970s. Before this, computers used relays, delay line memory or various kinds of vacuum tube arrangements to implement "main" memory functions (i.e., hundreds or thousands of bits), some of which were random access, some not. Latches built out of vacuum tube triodes, and later, out of discrete transistors, were used for smaller and faster memories such as registers and (random access) register banks. Prior to the development of integrated ROM circuits, permanent (or read-only) random access memory was often constructed using semiconductor diode matrices driven by address decoders.
Types of RAM
Modern types of writable RAM generally store a bit of data in either the state of a flip-flop, as in SRAM (static RAM), or as a charge in a capacitor (or transistor gate), as in DRAM (dynamic RAM), EPROM, EEPROM and Flash. Some types have circuitry to detect and/or correct random faults called memory errors in the stored data, using parity bits or error correction codes. RAM of the read-only type, ROM, instead uses a metal mask to permanently enable/disable selected transistors, instead of storing a charge in them.
As both SRAM and DRAM are volatile, other forms of computer storage, such as disks and magnetic tapes, have been used as persistent storage in traditional computers. Many newer products instead rely on flash memory to maintain data when not in use, such as PDAs or small music players. Certain personal computers, such as many rugged computers and netbooks, have also replaced magnetic disks with flash drives. With flash memory, only the NOR type is capable of true random access, allowing direct code execution, and is therefore often used instead of ROM; the lower cost NAND type is commonly used for bulk storage in memory cards and solid-state drives.
Memory hierarchy
Many computer systems have a memory hierarchy consisting of CPU registers, on-die SRAM caches, external caches, DRAM, paging systems, and virtual memory or swap space on a hard drive. This entire pool of memory may be referred to as "RAM" by many developers, even though the various subsystems can have very different access times, violating the original concept behind the random access term in RAM. Even within a hierarchy level such as DRAM, the specific row, column, bank, rank, channel, or interleave organization of the components make the access time variable, although not to the extent that rotating storage media or a tape is variable. The overall goal of using a memory hierarchy is to obtain the higher possible average access performance while minimizing the total cost of entire memory system. (Generally, the memory hierarchy follows the access time with the fast CPU registers at the top and the slow hard drive at the bottom.)
In many modern personal computers, the RAM comes in an easily upgraded form of modules called memory modules or DRAM modules about the size of a few sticks of chewing gum. These can quickly be replaced should they become damaged or too small for current purposes. As suggested above, smaller amounts of RAM (mostly SRAM) are also integrated in the CPU and other ICs on the motherboard, as well as in hard-drives, CD-ROMs, and several other parts of the computer system.
Several new types of non-volatile RAM, which will preserve data while powered down, are under development. The technologies used include carbon nanotubes and the magnetic tunnel effect. In summer 2003, a 128 KB (128 × 210 bytes) magnetic RAM (MRAM) chip was manufactured with 0.18 µm technology. In June 2004, Infineon Technologies unveiled a 16 MB (16 × 220 bytes) prototype again based on 0.18 µm technology. Nantero built a functioning carbon nanotube memory prototype 10 GB (10 × 230 bytes) array in 2004. Whether some of these technologies will be able to eventually take a significant market share from either DRAM, SRAM, or flash-memory technology, however, remains to be seen.
Recent developments
Since 2006, "Solid-state drives" (based on flash memory) with capacities exceeding 642 gigabytes and performance far exceeding traditional disks have become available. This development has started to blur the definition between traditional random access memory and "disks", dramatically reducing the difference in performance. Also in development is research being done in the field of plastic magnets, which switch magnetic polarities based on light.
source: http://en.wikipedia.org/wiki/RAM
