Wednesday, 24 June 2015

Apple IOS 9

iOS 9 is the upcoming ninth release of the iOS mobile operating system designed by Apple Inc as the successor to iOS 8. It was announced at the company's Worldwide Developers Conference (WWDC) 2015 on June 8, 2015 with an expected release date of September 2015. iOS 9 includes many under the hood optimisations and improvements over its predecessor. History iOS 9 debuted at Apple's Worldwide Developers Conference (WWDC) 2015 on June 8, 2015, with iOS 9.0 beta 1 being made available to registered developers straight after the keynote, and a public beta "coming soon" in July. [1][2] iOS 9 will see a public release date sometime in Autumn (Northern Hemisphere) Features and Changes iOS 9 includes enhancements to built in applications such as Notes which adds support for sharing from the Safari web browser, adding a list, making bullets, and changing the font. iOS 9 also includes a new Apple News app which ties in with other news sources such as The New York Times,CNN,Wired,and ESPN to bring one unified experience in the way users read, experience, and discover news. [4] Also, Apple Maps adds support for transit directions in Baltimore,Berlin,Chicago,London,Los Angeles,Mexico City,New York City, Paris,Philadelphia,San Francisco, Shanghai,Toronto,and Washington D.C. upon launch. [5] One of the other enhancements made to the Maps app in iOS 9 is that users get recommendations to points of interest, restaurants, etc. based on what time of day it is or the users' interests. There will also be an icon that will inform users if a retailer selected inside of Apple Maps supports Apple Pay or not. The name of the Passbook application was changed to Wallet and many new enhancements were made to Apple Pay such as Discover Credit/Debit Card support, loyalty card support, and support for Apple Pay in the UK. [6] iOS 9 also adds many productive features to the iPad lineup. These include Split-screen multitasking, slide over, and picture in picture support for enhanced multitasking similar to the experience found on OS X El Capitan. iPad users also receive better ways to manipulate text such as a new two finger gesture over the keyboard that helps the user slide around the page they are using as well as cut, copy, and paste with the included buttons on the keyboard. [4][7] Other things were changed that were not so obvious. The system font has changed to Apple's very own San Francisco font,used on the Apple Watch. Previously, the font used was Helvetica Neue,used both in iOS 7/8, and OS X Yosemite. The keyboard has been fixed so that when you deselect the shift key, you are able to see lowercase letter representations, in comparison to the all-caps representations on previous iOS versions. The multitasking pane has been redesigned on iPhone and iPod Touch. The quick contact information previously located in the multitasking pane was removed. As of iOS 9 Developer Beta 1, there is no button or function to kill all apps at once. Also noticeably, the newly announced News app (to replace Newsstand and compete with other News services such as Flipboard) is currently absent in the Beta version. Siri was enhanced in a major way with iOS 9. Siri is now aware of contextual info that a user is viewing on a page to provide better help to the user. For example, if a user is shopping for something online, the user can tell Siri "Remind me about This when I get home" and Siri will remind them to complete their purchase once they get home. Also, Siri is integrated into Spotlight Search to provide at-a-glance info to the user such as weather, sports scores, news, etc. Also, Spotlight provides info about places nearby that the user may want to visit based on time of day or location and provides suggested apps based on what is used most during that time of day (to compete head-on with Google Now). Spotlight can be accessed by swiping left of the 1st page of the home screen, similar to the previous search function on iOS 6. As of Beta 1, Spotlight is still available by swiping down as well. Siri also has a new feature called "Proactive" in which it helps users by doing things such as automatically adding an event to the calendar based on a message in the Mail app. Siri has been redesigned to be similar to the Apple Watch version of Siri as well. [8] iOS 9 also includes many under the hood improvements such as improved performance, better battery life such as a new low power mode, improved security such as advanced encryption and new 6-digit passcodes for Touch ID users instead of 4. [9] iOS 9 also introduces a new two-factor authentication for better security. [10] iOS 9 is available for all devices that were supported on iOS 8 and for the first time since iPhone OS 3 no device was dropped from one iOS to another. [11] However, devices powered by the A5 chip will have very limited support for many of the features on iOS 9 such as split-screen multitasking due to hardware constraints.

Sunday, 21 June 2015

8086 microprocessor

The 8086 ("eighty eighty-six", also called iAPX 86) is a 16-bit microprocessor chip designed by Intel between early 1976 and mid-1978, when it was released. The Intel 8088, released in 1979, was a slightly modified chip with an external 8-bit data bus (allowing the use of cheaper and fewer supporting ICs [note 1] ), and is notable as the processor used in the original IBM PC design, including the widespread version called IBM PC XT. The 8086 gave rise to the x86 architecture which eventually became Intel's most successful line of processors. In 1972, Intel launched the 8008,the first 8-bit microprocessor. [note 2] It implemented an instruction set designed by Datapoint corporation with programmable CRT terminals in mind, which also proved to be fairly general purpose. The device needed several additional ICs to produce a functional computer, in part due to it being packaged in a small 18-pin "memory package", which ruled out the use of a separate address bus (Intel was primarily a DRAM manufacturer at the time). Two years later,Intel launched the 8080, [note 3] employing the new 40-pin DIL packages originally developed for calculator ICs to enable a separate address bus. It had an extended instruction set that was source (not binary) compatible with the 8008 and also included some 16-bit instructions to make programming easier. The 8080 device, often described as "the first truly useful microprocessor" [citation needed] ,was eventually replaced by the depletion-load based 8085 (1977) which sufficed with a single +5 V power supply instead of the three different operating voltages of earlier chips. [note 4] Other well known 8-bit microprocessors that emerged during these years were Motorola 6800 (1974), General Instrument PIC16X (1975), MOS Technology 6502 (1975), Zilog Z80 (1976), and Motorola 6809 (1978) The 8086 project started in May 1976 and was originally intended as a temporary substitute for the ambitious and delayed iAPX 432 project. It was an attempt to draw attention from the less-delayed 16- and 32-bit processors of other manufacturers (such as Motorola,Zilog,and National Semiconductor) and at the same time to counter the threat from the Zilog Z80 (designed by former Intel employees), which became very successful. Both the architecture and the physical chip were therefore developed rather quickly by a small group of people, and using the same basic microarchitecture elements and physical implementation techniques as employed for the slightly older 8085 (and for which the 8086 also would function as a continuation). Marketed as source compatible,the 8086 was designed to allow assembly language for the 8008, 8080, or 8085 to be automatically converted into equivalent (suboptimal) 8086 source code, with little or no hand-editing. The programming model and instruction set was (loosely) based on the 8080 in order to make this possible. However, the 8086 design was expanded to support full 16-bit processing, instead of the fairly basic 16-bit capabilities of the 8080/8085. New kinds of instructions were added as well; full support for signed integers, base+offset addressing, and self-repeating operations were akin to the Z80 design [3] but were all made slightly more general in the 8086. Instructions directly supporting nested ALGOL-family languages such as Pascal and PL/M were also added. According to principal architect Stephen P. Morse, this was a result of a more software centric approach than in the design of earlier Intel processors (the designers had experience working with compiler implementations). Other enhancements included microcoded multiply and divide instructions and a bus structure better adapted to future coprocessors (such as 8087 and 8089) and multiprocessor systems. The first revision of the instruction set and high level architecture was ready after about three months, [note 5] and as almost no CAD tools were used, four engineers and 12 layout people were simultaneously working on the chip. [note 6] The 8086 took a little more than two years from idea to working product, which was considered rather fast for a complex design in 1976–1978. The 8086 was sequenced [note 7] using a mixture of random logic [4] and microcode and was implemented using depletion-load nMOS circuitry with approximately 20,000 active transistors (29,000 counting all ROM and PLA sites). It was soon moved to a new refined nMOS manufacturing process called HMOS (for High performance MOS) that Intel originally developed for manufacturing of fast static RAM products. [note 8] This was followed by HMOS-II, HMOS-III versions, and, eventually, a fully static CMOS version for battery powered devices, manufactured using Intel's CHMOS processes. [note 9] The original chip measured 33 mm² and minimum feature size was 3.2 μm. The architecture was defined by Stephen P. Morse with some help and assistance by Bruce Ravenel (the architect of the 8087) in refining the final revisions. Logic designer Jim McKevitt and John Bayliss were the lead engineers of the hardware-level development team [note 10] and Bill Pohlman the manager for the project. The legacy of the 8086 is enduring in the basic instruction set of today's personal computers and servers; the 8086 also lent its last two digits to later extended versions of the design, such as the Intel 286 and the Intel 386,all of which eventually became known as the x86 family. (Another reference is that the PCI Vendor ID for Intel devices is 8086 All internal registers, as well as internal and external data buses, are 16 bits wide, which firmly established the "16-bit microprocessor" identity of the 8086. A 20-bit external address bus provides a 1 MB physical address space (2 20 = 1,048,576). This address space is addressed by means of internal memory "segmentation". The data bus is multiplexed with the address bus in order to fit all of the control lines into a standard 40-pin dual in-line package. It provides a 16-bit I/O address bus, supporting 64 KB of separate I/O space. The maximum linear address space is limited to 64 KB, simply because internal address/index registers are only 16 bits wide. Programming over 64 KB memory boundaries involves adjusting the segment registers (see below); this difficulty existed until the 80386 architecture introduced wider (32-bit) registers (the memory management hardware in the 80286 did not help in this regard, as its registers are still only 16 bits wide). Some of the control pins, which carry essential signals for all external operations, have more than one function depending upon whether the device is operated in min or max mode. The former mode was intended for small single-processor systems, while the latter was for medium or large systems using more than one processor. 8086 has a 16-bit flags register. Nine of these condition code flags are active, and indicate the current state of the processor: Carry flag (CF), Parity flag (PF), Auxiliary carry flag (AF), Zero flag (ZF), Sign flag (SF), Trap flag (TF), Interrupt flag (IF), Direction flag (DF), and Overflow flag (OF). There are also four 16-bit segment registers (see figure) that allow the 8086 CPU to access one megabyte of memory in an unusual way. Rather than concatenating the segment register with the address register, as in most processors whose address space exceeded their register size, the 8086 shifts the 16-bit segment only four bits left before adding it to the 16-bit offset (16×segment + offset), therefore producing a 20-bit external (or effective or physical) address from the 32-bit segment:offset pair. As a result, each external address can be referred to by 2 12 = 4096 different segment:offset pairs.

About 8085 microprocessor

The Intel 8085 ("eighty-eighty-five") is an 8-bit microprocessor produced by Intel and introduced in 1977. [citation needed] It is software-binary compatible with the more-famous Intel 8080 with only a few minor instructions added. However, it required less support circuitry, allowing simpler and less expensive microcomputer systems to be built. The "5" in the part number highlighted the fact that the 8085 uses a single +5-Volt (V) power supply by using depletion mode transistors, rather than requiring the +5 V, −5 V and +12 V supplies needed by the 8080. This brought it up with the competing Z80,a popular 8080-derived CPU introduced the year before. These processors could be used in computers running the CP/M operating system. The 8085 was supplied in a 40-pin DIP package. To maximise the functions on the available pins, the 8085 used a multiplexed address/data bus. However, an 8085 circuit would require an 8-bit address latch so Intel manufactured several support chips with an address latch built in. These include the 8755, with an address latch, 2 KB of EPROM and 16 I/O pins, and the 8155 with 256 bytes of RAM, 22 I/O pins and a 14 bit programmable Timer/Counter. The multiplexed address/data bus reduced the number of PCB tracks between the 8085 and such memory and I/O chips. Both the 8080 and the 8085 were eclipsed by the Zilog Z80 for desktop computers, which took over most of the CP/M computer market as well as a share of the booming home computer market in the early-to-mid-1980s. The 8085 had a long life as a controller. Once designed into such products as the DECtape controller and the VT102 video terminal in the late 1970s, it served for new production throughout the lifetime of those products. This was typically longer than the product life of desktop computers. The 8085 is a conventional von Neumann design based on the Intel 8080. Unlike the 8080 it does not multiplex state signals onto the data bus, but the 8-bit data bus is instead multiplexed with the lower part of the 16-bit address bus to limit the number of pins to 40. Pin No. 40 is used for the power supply (+5 V) and pin No. 20 for ground. Pin No. 39 is used as the hold pin. Pins No. 15 to No. 8 are generally used for address buses. The processor was designed using nMOS circuitry and the later "H" versions were implemented in Intel's enhanced nMOS process called HMOS, originally developed for fast static RAM products. Only a 5 volt supply is needed, like competing processors and unlike the 8080. The 8085 uses approximately 6,500 transistors. [1] The 8085 incorporates the functions of the 8224 (clock generator) and the 8228 (system controller), increasing the level of integration. A downside compared to similar contemporary designs (such as the Z80) is the fact that the buses required demultiplexing; however, address latches in the Intel 8155, 8355, and 8755 memory chips allowed a direct interface, so an 8085 along with these chips is almost a complete system. The 8085 has extensions to support new interrupts, with three maskable vectored interrupts (RST 7.5, RST 6.5 and RST 5.5), one non-maskable interrupt (TRAP), and one externally serviced interrupt (INTR). The RST n.5 interrupts refer to actual pins on the processor, a feature which permitted simple systems to avoid the cost of a separate interrupt controller. Interrupts are enabled by the EI instruction and disabled by the DI instruction. Like the 8080, the 8085 can accommodate slower memories through externally generated wait states (pin 35, READY), and has provisions for Direct Memory Access (DMA) using HOLD and HLDA signals (pins 39 and 38). An improvement over the 8080 is that the 8085 can itself drive a piezoelectric crystal directly connected to it, and a built in clock generator generates the internal high amplitude two-phase clock signals at half the crystal frequency (a 6.14 MHz crystal would yield a 3.07 MHz clock, for instance). The 8085 is a binary compatible follow up on the 8080, using the same basic instruction set as the 8080. Only a few minor instructions were new to the 8085 above the 8080 set. The processor has seven 8-bit registers accessible to the programmer, named A, B, C, D, E, H, and L, where A is the 8-bit accumulator and the other six can be used as independent byte-registers or as three 16-bit register pairs, BC, DE, and HL, depending on the particular instruction. Some instructions use HL as a (limited) 16-bit accumulator. As in the 8080, the contents of the memory address pointed to by HL could be accessed as pseudo register M. It also has a 16-bit program counter and a 16-bit stack pointer to memory (replacing the 8008's internal stack). Instructions such as PUSH PSW, POP PSW affected the Program Status Word (accumulator and flags). The accumulator stores the results of arithmetic and logical operations, and the flags register bits (sign, zero, auxiliary carry, parity, and carry flags) are set or cleared according to the results of these operations. Intel produced a series of development systems for the 8080 and 8085, known as the MDS-80 Microprocessor System. The original development system had an 8080 processor. Later 8085 and 8086 support was added including ICE (in-circuit emulators). It is a large and heavy desktop box, about a 20" cube (in the Intel corporate blue color) which included a CPU, monitor, and a single 8 inch floppy disk drive. Later an external box was available with two more floppy drives. It runs the ISIS operating system and can also operate an emulator pod and an external EPROM programmer. This unit uses the Multibus card cage which was intended just for the development system. A surprising number of spare card cages and processors were being sold, leading to the development of the Multibus as a separate product. The later iPDS is a portable unit, about 8" x16" x20", with a handle. It has a small green screen, a keyboard built into the top, a 5¼ inch floppy disk drive, and ran the ISIS-II operating system. It can also accept a second 8085 processor, allowing a limited form of multi-processor operation where both processors run simultaneously and independently. The screen and keyboard can be switched between them, allowing programs to be assembled on one processor (large programs took awhile) while files are edited in the other. It has a bubble memory option and various programming modules, including EPROM and Intel 8048 and 8051 programming modules which are plugged into the side, replacing stand-alone device programmers. In addition to an 8080/8085 assembler, Intel produced a number of compilers including PL/M-80 and Pascal languages, and a set of tools for linking and statically locating programs to enable them to be burnt into EPROMs and used in embedded systems. A lower cost SDK-85 System Design Kit board contains an 8085 CPU, 8355 ROM containing a debugging monitor program, 8155 RAM and 22 I/O, 8279 hex keypad and 8-digit 7-segment LED, TTY (Teletype) 20 mA current loop serial interface. Pads were available for one more 2Kx8 8755 EPROM and another 256 byte RAM 8155 I/O Timer/Counter could be optionally added. All data, control and address signals are available on dual pin headers and a large prototype area is provided. Application- For the extensive use of 8085 in various applications, the microprocessor is provided with an instruction set which consists of various instructions such as MOV, ADD, SUB, JMP, etc. These instructions are written in the form of a program which is used to perform various operations such as branching, addition, subtraction, bitwise logical and bit shift operations. More complex operations and other arithmetic operations must be implemented in software. For example, multiplication is implemented using a multiplication algorithm. The 8085 processor is used in a few early personal computers, for example, the TRS-80 Model 100 line used an OKI manufactured 80C85 (MSM80C85ARS). The CMOS version 80C85 of the NMOS/HMOS 8085 processor has several manufacturers. Some manufacturers provide variants with additional functions such as additional instructions. [citation needed] The rad-hard version of the 8085 has been in on-board instrument data processors for several NASA and ESA space physics missions in the 1990s and early 2000s, including CRRES,Polar,FAST,Cluster, HESSI,the Sojourner Mars Rover, [2] and THEMIS. The Swiss company SAIA used the 8085 and the 8085-2 as the CPUs of their PCA1 line of programmable logic controllers during the 1980s. Pro-Log Corp. put the 8085 and supporting hardware on an STD Bus format card containing CPU, RAM, sockets for ROM/EPROM, I/O and external bus interfaces. The included Instruction Set Reference Card uses entirely different mnemonics for the Intel 8085 CPU, as the product was a direct competitor to Intel's Multibus card offerings.