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34-614: The Apple A6X is a 32-bit system-on-a-chip (SoC) designed by Apple Inc. , part of the Apple silicon series. It was introduced with and only used in the 4th generation iPad , on October 23, 2012. It is a high-performance variant of the Apple A6 and the last 32-bit chip Apple used on an iOS device before Apple switched to 64-bit . Apple claims the A6X has twice the CPU performance and up to twice

68-427: A time base generator that would sweep the selected locations, reading from or writing to the internal registers, normally implemented as flip-flops . Reading the memory took place via a secondary effect caused by the writing operation. During the short period when the write takes place, the redistribution of charges in the phosphor creates an electrical current that induces voltage in any nearby conductors . This

102-677: A 17-instruction program to calculate the highest proper factor of numbers as large as 2 . Tradition at the university has it that this was the only program Kilburn ever wrote. Williams tubes tended to become unreliable with age, and most working installations had to be hand tuned. By contrast, mercury delay-line memory was slower and not random access, as the bits were presented serially, which complicated programming. Delay lines also needed hand tuning, but did not age as badly and enjoyed some success in early digital electronic computing despite their data rate, weight, cost, thermal and toxicity problems. The Manchester Mark 1 , which used Williams tubes,

136-610: A mirror surface. HDR imagery allows for the reflection of highlights that can still be seen as bright white areas, instead of dull grey shapes. A 32-bit file format is a binary file format for which each elementary information is defined on 32 bits (or 4 bytes ). An example of such a format is the Enhanced Metafile Format . Williams tube The Williams tube , or the Williams–Kilburn tube named after inventors Freddie Williams and Tom Kilburn ,

170-405: A slight positive charge in the immediate region of the beam where there is a deficit of electrons, and a slight negative charge around the dot where those electrons land. The resulting charge well remains on the surface of the tube for a fraction of a second while the electrons flow back to their original locations. The lifetime depends on the electrical resistance of the phosphor and the size of

204-413: A total of 96 bits per pixel. 32-bit-per-channel images are used to represent values brighter than what sRGB color space allows (brighter than white); these values can then be used to more accurately retain bright highlights when either lowering the exposure of the image or when it is seen through a dark filter or dull reflection. For example, a reflection in an oil slick is only a fraction of that seen in

238-435: A usable lifetime. This places an upper limit on the memory density , and each Williams tube could typically store about 256 to 2560 bits of data. Because the electron beam is essentially inertia-free and can be moved anywhere on the display, the computer can access any location, making it a random access memory. Typically, the computer would load the memory address as an X and Y pair into the driver circuitry and then trigger

272-402: Is a 32-bit machine, with 32-bit registers and instructions that manipulate 32-bit quantities, but the external address bus is 36 bits wide, giving a larger address space than 4 GB, and the external data bus is 64 bits wide, primarily in order to permit a more efficient prefetch of instructions and data. Prominent 32-bit instruction set architectures used in general-purpose computing include

306-425: Is an early form of computer memory . It was the first random-access digital storage device, and was used successfully in several early computers. The Williams tube works by displaying a grid of dots on a cathode-ray tube (CRT). Due to the way CRTs work, this creates a small charge of static electricity over each dot. The charge at the location of each of the dots is read by a thin metal sheet just in front of

340-516: Is manufactured by Samsung on a High-κ metal gate (HKMG) 32 nm process. It has a die with an area of 123 mm, 30% larger than the A6. 32-bit 32-bit designs have been used since the earliest days of electronic computing, in experimental systems and then in large mainframe and minicomputer systems. The first hybrid 16/32-bit microprocessor , the Motorola 68000 , was introduced in

374-490: Is read by placing a thin metal sheet just in front of the display side of the CRT. During a read operation, the beam first writes to the selected bit locations on the display. Those locations that were previously written to are already depleted of electrons, so no current flows, and no voltage appears on the plate. This allows the computer to determine there was a "1" in that location. If the location had not been written to previously,

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408-606: The 8088/8086 or 80286 , 16-bit microprocessors with a segmented address space where programs had to switch between segments to reach more than 64 kilobytes of code or data. As this is quite time-consuming in comparison to other machine operations, the performance may suffer. Furthermore, programming with segments tend to become complicated; special far and near keywords or memory models had to be used (with care), not only in assembly language but also in high level languages such as Pascal , compiled BASIC , Fortran , C , etc. The 80386 and its successors fully support

442-536: The Apple A6 . It includes an integrated quad-core PowerVR SGX554MP4 graphics processing unit (GPU) running at 300 MHz and a quad-channel memory subsystem . The memory subsystem supports LPDDR2-1066 DRAM, increasing the theoretical memory bandwidth to 17 GB/s. Unlike the A6 , but similar to the A5X , the A6X is covered with a metal heat spreader , includes no RAM, and is not a package-on-package (PoP) assembly. The A6X

476-769: The IBM System/360 , IBM System/370 (which had 24-bit addressing), System/370-XA , ESA/370 , and ESA/390 (which had 31-bit addressing), the DEC VAX , the NS320xx , the Motorola 68000 family (the first two models of which had 24-bit addressing), the Intel IA-32 32-bit version of the x86 architecture, and the 32-bit versions of the ARM , SPARC , MIPS , PowerPC and PA-RISC architectures. 32-bit instruction set architectures used for embedded computing include

510-551: The IBM System/360 Model 30 had an 8-bit ALU, 8-bit internal data paths, and an 8-bit path to memory, and the original Motorola 68000 had a 16-bit data ALU and a 16-bit external data bus, but had 32-bit registers and a 32-bit oriented instruction set. The 68000 design was sometimes referred to as 16/32-bit . However, the opposite is often true for newer 32-bit designs. For example, the Pentium Pro processor

544-448: The integer representation used. With the two most common representations, the range is 0 through 4,294,967,295 (2 − 1) for representation as an ( unsigned ) binary number , and −2,147,483,648 (−2 ) through 2,147,483,647 (2 − 1) for representation as two's complement . One important consequence is that a processor with 32-bit memory addresses can directly access at most 4  GiB of byte-addressable memory (though in practice

578-533: The 16-bit segments of the 80286 but also segments for 32-bit address offsets (using the new 32-bit width of the main registers). If the base address of all 32-bit segments is set to 0, and segment registers are not used explicitly, the segmentation can be forgotten and the processor appears as having a simple linear 32-bit address space. Operating systems like Windows or OS/2 provide the possibility to run 16-bit (segmented) programs as well as 32-bit programs. The former possibility exists for backward compatibility and

612-423: The 68000 family and ColdFire , x86, ARM, MIPS, PowerPC, and Infineon TriCore architectures. On the x86 architecture , a 32-bit application normally means software that typically (not necessarily) uses the 32-bit linear address space (or flat memory model ) possible with the 80386 and later chips. In this context, the term came about because DOS , Microsoft Windows and OS/2 were originally written for

646-452: The PC and server market has moved on to 64 bits with x86-64 and other 64-bit architectures since the mid-2000s with installed memory often exceeding the 32-bit 4G RAM address limits on entry level computers. The latest generation of smartphones have also switched to 64 bits. A 32-bit register can store 2 different values. The range of integer values that can be stored in 32 bits depends on

680-409: The data visible, while other tubes were purpose-built without such a coating. The presence or absence of this coating had no effect on the operation of the tube, and was of no importance to the operators, since the face of the tube was covered by the pickup plate. If a visible output was needed, a second tube connected in parallel with the storage tube, with a phosphor coating, but without a pickup plate,

714-723: The display. Since the display faded over time, it was periodically refreshed. It operates faster than earlier acoustic delay-line memory , at the speed of the electrons inside the vacuum tube, rather than at the speed of sound . The system was adversely affected by nearby electrical fields, and required frequent adjustment to remain operational. Williams–Kilburn tubes were used primarily on high-speed computer designs. Williams and Kilburn applied for British patents on 11 December 1946, and 2 October 1947, followed by United States patent applications on 10 December 1947, and 16 May 1949. The Williams tube depends on an effect called secondary emission that occurs on cathode-ray tubes (CRTs). When

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748-407: The electron beam strikes the phosphor that forms the display surface, it normally causes it to illuminate. If the beam energy is above a given threshold (depending on the phosphor mix) it also causes electrons to be struck out of the phosphor. These electrons travel a short distance before being attracted back to the CRT surface and falling on it a short distance away. The overall effect is to cause

782-574: The first decades of 32-bit architectures (the 1960s to the 1980s). Older 32-bit processor families (or simpler, cheaper variants thereof) could therefore have many compromises and limitations in order to cut costs. This could be a 16-bit ALU , for instance, or external (or internal) buses narrower than 32 bits, limiting memory size or demanding more cycles for instruction fetch, execution or write back. Despite this, such processors could be labeled 32-bit , since they still had 32-bit registers and instructions able to manipulate 32-bit quantities. For example,

816-455: The graphics performance of its predecessor, the Apple A5X . Software updates for the 4th generation iPad ended in 2019 with the release of iOS 10.3.4 for cellular models, thus ceasing support for this chip as it was discontinued with the release of iOS 11 in 2017. The A6X features a 1.4 GHz custom Apple-designed ARMv7-A architecture based dual-core CPU called Swift, introduced in

850-550: The late 1970s and used in systems such as the original Apple Macintosh . Fully 32-bit microprocessors such as the HP FOCUS , Motorola 68020 and Intel 80386 were launched in the early to mid 1980s and became dominant by the early 1990s. This generation of personal computers coincided with and enabled the first mass-adoption of the World Wide Web . While 32-bit architectures are still widely-used in specific applications,

884-412: The latter is usually meant to be used for new software development . In digital images/pictures, 32-bit usually refers to RGBA color space ; that is, 24-bit truecolor images with an additional 8-bit alpha channel . Other image formats also specify 32 bits per pixel, such as RGBE . In digital images, 32-bit sometimes refers to high-dynamic-range imaging (HDR) formats that use 32 bits per channel,

918-468: The limit may be lower). The world's first stored-program electronic computer , the Manchester Baby , used a 32-bit architecture in 1948, although it was only a proof of concept and had little practical capacity. It held only 32 32-bit words of RAM on a Williams tube , and had no addition operation, only subtraction. Memory, as well as other digital circuits and wiring, was expensive during

952-446: The other was reading the next. Since the display would fade over time, the entire display had to be periodically refreshed using the same basic method. As the data is read and then immediately rewritten, this operation can be carried out by external circuitry while the central processing unit (CPU) was busy carrying out other operations. This refresh operation is similar to the memory refresh cycles of DRAM in modern systems. Since

986-410: The refresh process caused the same pattern to continually reappear on the display, there was a need to be able to erase previously written values. This was normally accomplished by writing to the display just beside the original location. The electrons released by this new write would fall into the previously written well, filling it. The original systems produced this effect by writing a small dash, which

1020-437: The starting point). This worked because the negative halo around the second dot would fill in the positive center of the first dot. A collection of dots or spaces, often one horizontal row on the display, represents a computer word. Increasing beam energy made the dots bigger and last longer, but required them to be further apart, since nearby dots would erase each other. The beam energy had to be large enough to produce dots with

1054-416: The well. The process of creating the charge well is used as the write operation in a computer memory, storing a single binary digit, or bit . A positively charged dot is erased (filling the charge well) by drawing a second dot immediately adjacent to the one to be erased (most systems did this by drawing a short dash starting at the dot position, the extension of the dash erased the charge initially stored at

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1088-437: The write process will create a well and a pulse will be read on the sheet, indicating a "0". Reading a memory location creates a charge well whether or not one was previously there, thus destroying the original contents of that location. So any read has to be followed by a rewrite to reinstate the original data. In some systems this was accomplished using a second electron gun inside the CRT that could write to one location while

1122-428: Was easy to accomplish without changing the master timers and simply producing the write current for a slightly longer period. The resulting pattern was a series of dots and dashes. There was a considerable amount of research on more effective erasing systems, with some systems using out-of-focus beams or complex patterns. Some Williams tubes were made from radar -type cathode-ray tubes with a phosphor coating that made

1156-641: Was used as a display device. Developed at the University of Manchester in England , it provided the program storage medium for the Manchester Baby , the first electronic stored-program computer , which first successfully ran a program on 21 June, 1948. Rather than the Williams tube memory being designed for the Baby, the Baby was a testbed to demonstrate the reliability of the memory. Tom Kilburn wrote

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