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83-481: A device with AOD enabled keeps a limited portion of the screen on during sleep mode . An Always-On Display may display a set of recent push notifications in place of a notification tone or LED signal, as well as information such as the time, date, and battery status of the device; they often may also be configured to also show various types of notifications as they arrive, or screensavers . Various devices have differing behavior for this feature. Some phones would have

166-589: A Forth interpreter, with much of the firmware being written in Forth. It was standardized by the IEEE as IEEE standard 1275-1994; firmware that implements that standard was used in PowerPC -based Macs and some other PowerPC-based machines, as well as Sun's own SPARC -based computers. The Advanced RISC Computing specification defined another firmware standard, which was implemented on some MIPS -based and Alpha -based machines and

249-569: A power outage , unlike other operating systems, hibernate was never offered as an option. In 2005, some Macs running Mac OS X v10.4 began to support Safe Sleep. The feature saves the contents of volatile memory to the system hard disk each time the Mac enters Sleep mode. The Mac can instantaneously wake from sleep mode if power to the RAM has not been lost. However, if the power supply was interrupted, such as when removing batteries without an AC power connection,

332-660: A boot device and execute it. Firmware compatible with the BIOS on the IBM Personal Computer is used in IBM PC compatible computers. The UEFI was developed by Intel, originally for Itanium -based machines, and later also used as an alternative to the BIOS in x86 -based machines, including Apple Macs using Intel processors . Unix workstations originally had vendor-specific ROM-based firmware. Sun Microsystems later developed OpenBoot , later known as Open Firmware, which incorporated

415-486: A campaign was launched to add a set of power characters to Unicode . In February 2015, the proposal was accepted by Unicode and the characters were included in Unicode 9.0. The characters are in the " Miscellaneous Technical " block, with code points 23FB-FE. The symbol is ⏾ (⏾)—defined as "Power Sleep Symbol". Wake-on-LAN (WoL or WOL) is an Ethernet or Token Ring computer networking standard that allows

498-492: A cassette tape drive mounted on the front panel; this sets up a boot loader in RAM which is then executed. However, since this makes few assumptions about the system it can equally well be used to load diagnostic (Maintenance Test Routine) tapes which display an intelligible code on the front panel even in cases of gross CPU failure. In the IBM System/360 and its successors, including the current z/Architecture machines,

581-421: A complete input or output operation. The same hardware logic could be used to load the contents of a punch card (the most typical ones) or other input media, such as a magnetic drum or magnetic tape , that contained a bootstrap program by pressing a single button. This booting concept was called a variety of names for IBM computers of the 1950s and early 1960s, but IBM used the term "Initial Program Load" with

664-448: A computer also is called rebooting , which can be "hard", e.g. after electrical power to the CPU is switched from off to on, or "soft", where the power is not cut. On some systems, a soft boot may optionally clear RAM to zero. Both hard and soft booting can be initiated by hardware such as a button press or by a software command. Booting is complete when the operative runtime system , typically

747-445: A computer to be turned on or awakened from sleep mode by a network message. It is based upon AMD 's Magic Packet Technology , which was co-developed by AMD and Hewlett-Packard, following its proposal as a standard in 1995. The standard saw quick adoption thereafter through IBM , Intel and others. Equivalent terms include wake on WAN, remote wake-up, power on by LAN, power up by LAN, resume by LAN, resume on LAN and wake up on LAN. If

830-511: A fixed program into memory when its start button was pressed. The program stored on this device, which David Wheeler completed in late 1948, loaded further instructions from punched tape and then executed them. The first programmable computers for commercial sale, such as the UNIVAC I and the IBM 701 included features to make their operation simpler. They typically included instructions that performed

913-716: A frequent occurrence with relatively low-cost, "part-time-duty" hardware, such as the Teletype Model 33 ASR. (Friden Flexowriters were far more reliable, but also comparatively costly.) The earliest microcomputers, such as the Altair 8800 (released first in 1975) and an even earlier, similar machine (based on the Intel 8008 CPU) had no bootstrapping hardware as such. When powered-up, the CPU would see memory that would contain random data. The front panels of these machines carried toggle switches for entering addresses and data, one switch per bit of

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996-564: A printed circuit card, the M792, that plugged into the Unibus and held a 32 by 16 array of semiconductor diodes. With all 512 diodes in place, the memory contained all "one" bits; the card was programmed by cutting off each diode whose bit was to be "zero". DEC also sold versions of the card, the BM792-Yx series, pre-programmed for many standard input devices by simply omitting the unneeded diodes. Following

1079-449: A pulsed or red colored LED power light. In computers, entering a sleep state is roughly equivalent to "pausing" the state of the machine. When restored, the operation continues from the same point, having the same applications and files open. Sleep mode has gone by various names, including Stand By , Suspend and Suspend to RAM . Machine state is held in RAM and, when placed in sleep mode,

1162-434: A reboot may be the only method to return to a designated zero-state from an unintended, locked state. In addition to loading an operating system or stand-alone utility, the boot process can also load a storage dump program for diagnosing problems in an operating system. Boot is short for bootstrap or bootstrap load and derives from the phrase to pull oneself up by one's bootstraps . The usage calls attention to

1245-512: A researcher at CSELT , included an (external) ROM. Gruppi Speciali was, starting from 1975, a fully single-button machine booting into the operating system from a ROM memory composed from semiconductors, not from ferrite cores. Although the ROM device was not natively embedded in the computer of Gruppi Speciali, due to the design of the machine, it also allowed the single-button ROM booting in machines not designed for that (therefore, this "bootstrap device"

1328-452: A special program to load the actual operating system or standalone utility into main storage, and for this specific purpose "IPL Text" is placed on the disk by the stand-alone DASDI (Direct Access Storage Device Initialization) program or an equivalent program running under an operating system, e.g., ICKDSF, but IPL-able tapes and card decks are usually distributed with this "IPL Text" already present. IBM introduced some evolutionary changes in

1411-476: A start up program that could not be erased. Growth in the capacity of ROM has allowed ever more elaborate start up procedures to be implemented. There are many different methods available to load a short initial program into a computer. These methods reach from simple, physical input to removable media that can hold more complex programs. Early computers in the 1940s and 1950s were one-of-a-kind engineering efforts that could take weeks to program and program loading

1494-461: Is called a first-stage boot loader, and the program it loads is called a second-stage boot loader. On many embedded CPUs, the CPU built-in boot ROM , sometimes called the zero-stage boot loader, can find and load first-stage boot loaders. Examples of first-stage (hardware initialization stage) boot loaders include BIOS , UEFI , coreboot , Libreboot and Das U-Boot . On the IBM PC, the boot loader in

1577-484: Is given a command to transfer data to memory starting at address 00100; when that transfer finishes, the CPU jumps to address 00101. IBM's competitors also offered single button program load. A noteworthy variation of this is found on the Burroughs B1700 where there is neither a bootstrap ROM nor a hardwired IPL operation. Instead, after the system is reset it reads and executes microinstructions sequentially from

1660-417: Is impossible to natively boot an operating system other than the standard one. This is the opposite extreme of the scenario using switches mentioned above; it is highly inflexible but relatively error-proof and foolproof as long as all hardware is working normally. A common solution in such situations is to design a boot loader that works as a program belonging to the standard OS that hijacks the system and loads

1743-402: Is in use, which leads to an extra consumption of roughly 3% battery per day, assuming that AOD is in use 30% per day. On LCD displays, the backlight has to be turned on, even if only a part of the screen is showing information, so this feature consumes a significant amount of power compared to a notification LED. Some LCD displays use Transflective LCD . It uses a layer called a transflector. It

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1826-593: Is lost, it will use the hard disk to wake up. The user has the option of hibernating directly if they wish. On PCs that enable Modern Standby , Hybrid sleep feature is unavailable. In older versions prior to Windows Vista, sleep mode was under-used in business environments as it was difficult to enable organization-wide without resorting to third-party software. As a result, these earlier versions of Windows were criticized for wasting energy. A variety of third-party PC power management software exists for newer versions of Windows, offering features beyond those built into

1909-401: Is the current standard for power management , superseding APM (Advanced Power Management) and providing the backbone for sleep and hibernation on modern computers. Sleep mode corresponds to ACPI mode S3 . When a non-ACPI device is plugged in, Windows will sometimes disable stand-by functionality for the whole operating system. Without ACPI functionality, as seen on older hardware, sleep mode

1992-429: Is the process of starting a computer as initiated via hardware such as a button on the computer or by a software command. After it is switched on, a computer's central processing unit (CPU) has no software in its main memory , so some process must load software into memory before it can be executed. This may be done by hardware or firmware in the CPU, or by a separate processor in the computer system. Restarting

2075-534: Is typically made from a sheet polymer. It is similar to a one-way mirror but is not specular . Some smartwatches such as the Pebble Smartwatch and the Amazfit Stratos also use this technology. Under bright illumination (e.g. when exposed to daylight) the display acts mainly as a reflective display with the contrast being constant with illuminance . Typically, an ambient display solution which turns on

2158-402: Is usually a disk drive, hence the special significance of the 02h read-type command, but exactly the same procedure is also used to IPL from other input-type devices, such as tape drives, or even card readers, in a device-independent manner, allowing, for example, the installation of an operating system on a brand-new computer from an OS initial distribution magnetic tape. For disk controllers,

2241-400: Is usually restricted to turning off the monitor and spinning down the hard drive. Microsoft Windows 2000 and later support sleep at the operating system level (ACPI S3 state) without special drivers from the hardware manufacturer, except of video adapters . Windows Vista 's Hybrid sleep feature saves the contents of volatile memory to hard disk before entering sleep mode. If power to memory

2324-427: The 02h command also causes the selected device to seek to cylinder 0000h , head 0000h , simulating a Seek cylinder and head command, 07h , and to search for record 01h , simulating a Search ID Equal command, 31h ; seeks and searches are not simulated by tape and card controllers, as for these device classes a Read IPL command is simply a sequential read command. The disk, tape or card deck must contain

2407-469: The IBM 1401 system (c. 1958) used a card reader to load a program from a punched card. The 80 characters stored in the punched card were read into memory locations 001 to 080, then the computer would branch to memory location 001 to read its first stored instruction. This instruction was always the same: move the information in these first 80 memory locations to an assembly area where the information in punched cards 2, 3, 4, and so on, could be combined to form

2490-525: The IBM 7030 Stretch and later used it for their mainframe lines, starting with the System/360 in 1964. The IBM 701 computer (1952–1956) had a "Load" button that initiated reading of the first 36-bit word into main memory from a punched card in a card reader , a magnetic tape in a tape drive , or a magnetic drum unit, depending on the position of the Load Selector switch. The left 18-bit half-word

2573-565: The LOAD button. On the high end System/360 models, most System/370 and some later systems, the functions of the switches and the LOAD button are simulated using selectable areas on the screen of a graphics console, often an IBM 2250 -like device or an IBM 3270 -like device. For example, on the System/370 Model 158, the keyboard sequence 0-7-X (zero, seven and X, in that order) results in an IPL from

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2656-616: The Master Boot Record (MBR) and the Partition Boot Record (PBR) was coded to require at least 32 KB (later expanded to 64 KB ) of system memory and only use instructions supported by the original 8088 / 8086 processors. Second-stage (OS initialization stage) boot loaders, such as shim, GNU GRUB , rEFInd , BOOTMGR , Syslinux , NTLDR and iBoot , are not themselves operating systems, but are able to load an operating system properly and transfer execution to it;

2739-654: The SGI Visual Workstation x86-based workstations. When a computer is turned off, its software‍—‌including operating systems, application code, and data‍—‌remains stored on non-volatile memory . When the computer is powered on, it typically does not have an operating system or its loader in random-access memory (RAM). The computer first executes a relatively small program stored in read-only memory (ROM, and later EEPROM , NOR flash ) which support execute in place , to initialize CPU and motherboard, to initialize DRAM (especially on x86 systems), to access

2822-603: The Spectre GCR cartridge with the Macintosh system ROM in the game slot and turning the Atari on, it could "natively boot" the Macintosh operating system rather than Atari's own TOS . The IBM Personal Computer included ROM-based firmware called the BIOS ; one of the functions of that firmware was to perform a power-on self test when the machine was powered up, and then to read software from

2905-417: The front panel . Since the early minicomputers used magnetic-core memory , which did not lose its information when power was off, these bootstrap loaders would remain in place unless they were erased. Erasure sometimes happened accidentally when a program bug caused a loop that overwrote all of memory. Other minicomputers with such simple form of booting include Hewlett-Packard's HP 2100 series (mid-1960s),

2988-443: The operating system and some applications, is attained. The process of returning a computer from a state of sleep (suspension) does not involve booting; however, restoring it from a state of hibernation does. Minimally, some embedded systems do not require a noticeable boot sequence to begin functioning and when turned on may simply run operational programs that are stored in ROM. All computing systems are state machines , and

3071-552: The Altair 8800) in a commercial computer. According to Apple's ad announcing it "No More Switches, No More Lights ... the firmware in PROMS enables you to enter, display and debug programs (all in hex) from the keyboard." Due to the expense of read-only memory at the time, the Apple II booted its disk operating systems using a series of very small incremental steps, each passing control onward to

3154-448: The Atari's floppy drive was read for additional components during the boot process. There was a timeout delay that provided time to manually insert a floppy as the system searched for the extra components. This could be avoided by inserting a blank disk. The Atari ST hardware was also designed so the cartridge slot could provide native program execution for gaming purposes as a holdover from Atari's legacy making electronic games; by inserting

3237-523: The IBM PC and compatibles, the boot code must fit in the Master Boot Record (MBR) and the Partition Boot Record (PBR), which in turn are limited to a single sector; on the IBM System/360 , the size is limited by the IPL medium, e.g., card size, track size. On systems with those constraints, the first program loaded into RAM may not be sufficiently large to load the operating system and, instead, must load another, larger program. The first program loaded into RAM

3320-581: The IPL process, changing some details for System/370 Extended Architecture (S/370-XA) and later, and adding a new type of IPL for z/Architecture. Minicomputers , starting with the Digital Equipment Corporation (DEC) PDP-5 and PDP-8 (1965) simplified design by using the CPU to assist input and output operations. This saved cost but made booting more complicated than pressing a single button. Minicomputers typically had some way to toggle in short programs by manipulating an array of switches on

3403-474: The Intel x86 series are designed to execute this software after reset without outside help). This software contains rudimentary functionality to search for devices eligible to participate in booting, and load a small program from a special section (most commonly the boot sector ) of the most promising device, typically starting at a fixed entry point such as the start of the sector. Boot loaders may face peculiar constraints, especially in size; for instance, on

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3486-770: The Mac would wake from Safe Sleep instead, restoring memory contents from the hard drive. Safe Sleep capability is found in Mac models starting with the October 2005 revision of the PowerBook G4 (Double-Layer SD ). Mac OS X v10.4 or higher is also required. In 2012, Apple introduced Power Nap with OS X Mountain Lion (10.8) and select Mac models. Power Nap allows the Mac to perform tasks silently, such as iCloud syncing and Spotlight indexing. Only low energy tasks are performed when on battery power, while higher energy tasks are performed with AC power. Because of widespread use of this symbol,

3569-594: The RAM and to be able to respond to a wake-up event. A sleeping PC is on standby power , and this is covered by regulations in many countries, for example in the United States limiting such power under the One Watt Initiative , from 2010. In addition to a wake-up press of the power button, PCs can also respond to other wake cues, such as from keyboard, mouse, incoming telephone call on a modem , or local area network signal . A real-time clock alarm can schedule

3652-505: The VAX-11/730 had an 8085-based console processor. These console processors could boot the main processor from various storage devices. Some other superminicomputers, such as the VAX-11/750, implement console functions, including the first stage of booting, in CPU microcode. Typically, a microprocessor will, after a reset or power-on condition, perform a start-up process that usually takes

3735-617: The alternative OS. This technique was used by Apple for its A/UX Unix implementation and copied by various freeware operating systems and BeOS Personal Edition 5 . Some machines, like the Atari ST microcomputer , were "instant-on", with the operating system executing from a ROM . Retrieval of the OS from secondary or tertiary store was thus eliminated as one of the characteristic operations for bootstrapping. To allow system customizations, accessories, and other support software to be loaded automatically,

3818-619: The benefits of sleep mode and hibernation: The machine can resume instantaneously, but it can also be powered down completely (e.g. due to loss of power) without loss of data, because it is already effectively in a state of hibernation. This mode is called " hybrid sleep " in Microsoft Windows other than Windows XP. A hybrid mode is supported by some portable Apple Macintosh computers, compatible hardware running Windows Vista or newer, and Linux distributions running kernel 3.6 or newer. ACPI (Advanced Configuration and Power Interface)

3901-480: The boot process is known as Initial Program Load (IPL). IBM coined this term for the 7030 (Stretch) , revived it for the design of the System/360, and continues to use it in those environments today. In the System/360 processors, an IPL is initiated by the computer operator by selecting the three hexadecimal digit device address (CUU; C=I/O Channel address, UU=Control unit and Device address ) followed by pressing

3984-452: The computer being awakened is communicating via Wi-Fi , a supplementary standard called Wake on Wireless LAN (WoWLAN) must be employed. The message is usually sent to the target computer by a program executed on a device connected to the same local area network (LAN). It is also possible to initiate the message from another network by using subnet directed broadcasts or a WoL gateway service. Booting In computing , booting

4067-437: The computer cuts power to unneeded subsystems and places the RAM into a minimum power state, just sufficient to retain its data. Because of the large power saving, most laptops automatically enter this mode when the computer is running on batteries and the lid is closed. If undesired, the behavior can be altered in the operating system settings of the computer. A computer must consume some energy while sleeping in order to power

4150-649: The computer memory word and address bus. Simple additions to the hardware permitted one memory location at a time to be loaded from those switches to store bootstrap code. Meanwhile, the CPU was kept from attempting to execute memory content. Once correctly loaded, the CPU was enabled to execute the bootstrapping code. This process, similar to that used for several earlier minicomputers, was tedious and had to be error-free. The introduction of integrated circuit read-only memory (ROM), with its many variants, including mask-programmed ROMs , programmable ROMs (PROM), erasable programmable ROMs (EPROM), and flash memory , reduced

4233-402: The computer to automatically load instructions into memory from a device specified by the front panel's data switches, and then jump to loaded code. In a minicomputer with a paper tape reader, the first program to run in the boot process, the boot loader, would read into core memory either the second-stage boot loader (often called a Binary Loader ) that could read paper tape with checksum or

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4316-399: The computer to wake from sleep mode. Hibernation, also called Suspend to Disk on Linux, saves all computer operational data on the fixed disk before turning the computer off completely. On switching the computer back on, the computer is restored to its state prior to hibernation, with all programs and files open, and unsaved data intact. In contrast with standby mode, hibernation mode saves

4399-411: The computer's state on the hard disk, which requires no power to maintain, whereas standby mode saves the computer's state in RAM, which requires a small amount of power to maintain. Sleep mode and hibernation can be combined: the contents of RAM are first copied to non-volatile storage like for regular hibernation, but then, instead of powering down, the computer enters sleep mode. This approach combines

4482-594: The device address which was keyed into the input area. The Amdahl 470V/6 and related CPUs supported four hexadecimal digits on those CPUs which had the optional second channel unit installed, for a total of 32 channels. Later, IBM would also support more than 16 channels. The IPL function in the System/360 and its successors prior to IBM Z , and its compatibles such as Amdahl's, reads 24 bytes from an operator-specified device into main storage starting at real address zero. The second and third groups of eight bytes are treated as Channel Command Words (CCWs) to continue loading

4565-574: The feature since Apple Watch Series 5 (2019) and on iPhone 14 Pro in 2022. The Always-On Display feature does consume energy, although the Samsung Galaxy S7 series phones, and later phones that made the feature popular are built with AMOLED screens in which no power is needed for black pixels. On today's AMOLED phone displays, it is true that only a few pixels may need to be turned on but they do need to be moved to prevent pixel burn in . Colors, sensors and processors all consume energy while AOD

4648-429: The form of "begin execution of the code that is found starting at a specific address" or "look for a multibyte code at a specific address and jump to the indicated location to begin execution". A system built using that microprocessor will have the permanent ROM occupying these special locations so that the system always begins operating without operator assistance. For example, Intel x86 processors always start by running

4731-502: The instructions beginning at F000:FFF0, while for the MOS 6502 processor, initialization begins by reading a two-byte vector address at $ FFFD (MS byte) and $ FFFC (LS byte) and jumping to that location to run the bootstrap code. Apple Computer 's first computer, the Apple 1 introduced in 1976, featured PROM chips that eliminated the need for a front panel for the boot process (as was the case with

4814-415: The instructions by the CPU. Smaller computers often use less flexible but more automatic boot loader mechanisms to ensure that the computer starts quickly and with a predetermined software configuration. In many desktop computers, for example, the bootstrapping process begins with the CPU executing software contained in ROM (for example, the BIOS of an IBM PC ) at a predefined address (some CPUs, including

4897-441: The next phase of the gradually more complex boot process. (See Apple DOS: Boot loader ). Because so little of the disk operating system relied on ROM, the hardware was also extremely flexible and supported a wide range of customized disk copy protection mechanisms. (See Software Cracking: History .) Some operating systems, most notably pre-1995 Macintosh systems from Apple , are so closely interwoven with their hardware that it

4980-555: The nonvolatile device (usually block-addressed device, e.g. NAND flash, SSD) or devices from which the operating system programs and data can be loaded into RAM; in addition, this program may initialize display devices (such as GPUs ), text input devices (such as the keyboard ) and pointer input devices (such as the mouse ). The small program that starts this sequence is known as a bootstrap loader , bootstrap or boot loader . Often, multiple-stage boot loaders are used, during which several programs of increasing complexity load one after

5063-454: The older approach, the earlier PDP-1 has a hardware loader, such that an operator need only push the "load" switch to instruct the paper tape reader to load a program directly into core memory. The PDP-7 , PDP-9 , and PDP-15 successors to the PDP-4 have an added Read-In button to read a program in from paper tape and jump to it. The Data General Supernova used front panel switches to cause

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5146-425: The operating system from an outside storage medium. Pseudocode for the boot loader might be as simple as the following eight instructions: A related example is based on a loader for a Nicolet Instrument Corporation minicomputer of the 1970s, using the paper tape reader-punch unit on a Teletype Model 33 ASR teleprinter . The bytes of its second-stage loader are read from paper tape in reverse order. The length of

5229-496: The operating system subsequently initializes itself and may load extra device drivers . The second-stage boot loader does not need drivers for its own operation, but may instead use generic storage access methods provided by system firmware such as the BIOS, UEFI or Open Firmware , though typically with restricted hardware functionality and lower performance. Many boot loaders (like GNU GRUB, rEFInd, Windows's BOOTMGR, Syslinux, and Windows NT/2000/XP's NTLDR) can be configured to give

5312-460: The operating system. Most products offer Active Directory integration and per-user/per-machine settings with the more advanced offering multiple power plans, scheduled power plans, anti-insomnia features and enterprise power usage reporting. Sleep on macOS consists of the traditional sleep, Safe Sleep , and Power Nap . In System Preferences , Safe Sleep is referred to as sleep. Since Safe Sleep also allowed state to be restored in an event of

5395-460: The operator). Other systems may send hardware commands directly to peripheral devices or I/O controllers that cause an extremely simple input operation (such as "read sector zero of the system device into memory starting at location 1000") to be carried out, effectively loading a small number of boot loader instructions into memory; a completion signal from the I/O device may then be used to start execution of

5478-511: The original Data General Nova (1969), and DEC's PDP-4 (1962) and PDP-11 (1970). As the I/O operations needed to cause a read operation on a minicomputer I/O device were typically different for different device controllers, different bootstrap programs were needed for different devices. DEC later added, in 1971, an optional diode matrix read-only memory for the PDP-11 that stored a bootstrap program of up to 32 words (64 bytes). It consisted of

5561-453: The other in a process of chain loading . Some earlier computer systems, upon receiving a boot signal from a human operator or a peripheral device, may load a very small number of fixed instructions into memory at a specific location, initialize at least one CPU, and then point the CPU to the instructions and start their execution. These instructions typically start an input operation from some peripheral device (which may be switch-selectable by

5644-764: The physical size and cost of ROM. This allowed firmware boot programs to be included as part of the computer. The Data General Nova 1200 (1970) and Nova 800 (1971) had a program load switch that, in combination with options that provided two ROM chips, loaded a program into main memory from those ROM chips and jumped to it. Digital Equipment Corporation introduced the integrated-circuit-ROM-based BM873 (1974), M9301 (1977), M9312 (1978), REV11-A and REV11-C, MRV11-C, and MRV11-D ROM memories, all usable as bootstrap ROMs. The PDP-11/34 (1976), PDP-11/60 (1977), PDP-11/24 (1979), and most later models include boot ROM modules. An Italian telephone switching computer, called "Gruppi Speciali", patented in 1975 by Alberto Ciaramella ,

5727-417: The requirement that, if most software is loaded onto a computer by other software already running on the computer, some mechanism must exist to load the initial software onto the computer. Early computers used a variety of ad-hoc methods to get a small program into memory to solve this problem. The invention of read-only memory (ROM) of various types solved this paradox by allowing computers to be shipped with

5810-514: The screen off until new notifications arrive whereupon the display would either be active for a few seconds or remain on until the user interacts with the device to read or dismiss the notification (essentially having the entire screen serve as a larger notification LED); others instead have the phone screen activate when it detects input, such as being picked up or the screen interacted with. These versions are often called ambient displays , in contrast to "true" always-on displays, where at least part of

5893-450: The screen only when notifications are present, remains on, but turns off when they are dismissed will consume the least amount of battery power while still drawing the user's attention when required, in contrast to an Always-on Display which will keep the screen on, all of the time, to show some information, even if notifications may not be present. Since the date and time are less essential than battery status or notifications which may require

5976-556: The screen remains on at all times. Again depending on the manufacturer, not all apps may be supported for showing notifications with this feature - only first-party apps or popular apps may be supported. This technology was first introduced by Nokia in on the Nokia N70 and Nokia 6303 (on TFT display in 2008), and more widely adopted with its next generation AMOLED Symbian phones in 2010 (the Nokia N8, C7, C6-01 and E7). Later functionality

6059-426: The second stage loader is such that the final byte overwrites location 7. After the instruction in location 6 executes, location 7 starts the second stage loader executing. The second stage loader then waits for the much longer tape containing the operating system to be placed in the tape reader. The difference between the boot loader and second stage loader is the addition of checking code to trap paper tape read errors,

6142-425: The startup program (the first CCW is always simulated by the CPU and consists of a Read IPL command, 02h , with command chaining and suppress incorrect length indication being enforced). When the I/O channel commands are complete, the first group of eight bytes is then loaded into the processor's Program Status Word (PSW) and the startup program begins execution at the location designated by that PSW. The IPL device

6225-449: The stored program. Once this information was moved to the assembly area, the machine would branch to an instruction in location 080 (read a card) and the next card would be read and its information processed. Another example was the IBM 650 (1953), a decimal machine, which had a group of ten 10-position switches on its operator panel which were addressable as a memory word (address 8000) and could be executed as an instruction. Thus setting

6308-468: The switches to 7004000400 and pressing the appropriate button would read the first card in the card reader into memory (op code 70), starting at address 400 and then jump to 400 to begin executing the program on that card. The IBM 7040 and 7044 have a similar mechanism, in which the Load button causes the instruction set up in the entry keys on the front panel is executed, and the channel that instruction sets up

6391-462: The user multiple booting choices. These choices can include different operating systems (for dual or multi-booting from different partitions or drives), different versions of the same operating system (in case a new version has unexpected problems), different operating system loading options (e.g., booting into a rescue or safe mode ), and some standalone programs that can function without an operating system, such as memory testers (e.g., memtest86+ ),

6474-549: The user's immediate attention, an AOD can be customized in many app-based implementations to only show notifications or selectively choose what is shown. In some phones, the Always-On Display/Ambient Display feature can be toggled on a schedule, such as during nighttime, or when the proximity sensor detects that the device is in a pocket. There may be an option for the phone to keep the screen on only when there are notifications to be acknowledged or dismissed by

6557-419: The user. Sleep mode Sleep mode (or suspend to RAM ) is a low power mode for electronic devices such as computers, televisions, and remote controlled devices. These modes save significantly on electrical consumption compared to leaving a device fully on and, upon resume, allow the user to avoid having to reissue instructions or to wait for a machine to boot . Many devices signify this power mode with

6640-558: Was architecture-independent), e.g. the PDP-11. Storing the state of the machine after the switch-off was also in place, which was another critical feature in the telephone switching contest. Some minicomputers and superminicomputers include a separate console processor that bootstraps the main processor. The PDP-11/44 had an Intel 8085 as a console processor; the VAX-11/780 , the first member of Digital's VAX line of 32-bit superminicomputers, had an LSI-11 -based console processor, and

6723-421: Was one of many problems that had to be solved. An early computer, ENIAC , had no program stored in memory, but was set up for each problem by a configuration of interconnecting cables. Bootstrapping did not apply to ENIAC, whose hardware configuration was ready for solving problems as soon as power was applied. The EDSAC system, the second stored-program computer to be built, used stepping switches to transfer

6806-505: Was then executed as an instruction, which usually read additional words into memory. The loaded boot program was then executed, which, in turn, loaded a larger program from that medium into memory without further help from the human operator. The IBM 704 , IBM 7090 , and IBM 7094 had similar mechanisms, but with different load buttons for different devices. The term "boot" has been used in this sense since at least 1958. Other IBM computers of that era had similar features. For example,

6889-465: Was updated with Nokia Sleeping Screen app for last generation of Symbian smartphones (Nokia 808 and other) with features like custom standby screen from any image, and two themes for notifications design. It became a standard feature on most Nokia Lumia Windows Phones in 2013, paired with the Nokia Glance Screen app. The feature has since become more widely available on Android handsets. Apple has

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