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Boot ROM
The boot ROM is a type of ROM that is used for booting a computer system. There are two types: a mask boot ROM that cannot be changed afterwards and a boot EEPROM, which can contain an UEFI implementation. Purpose Upon power up, hardware usually starts uninitialized. To continue booting, the system may need to read a bootloader from some peripheral device. It is often easier to implement routines for reading from external storage devices in software than in hardware. A boot ROM provides a place to store this initial loading code, at a fixed location immediately available to the processor when execution starts. Operation The boot ROM is mapped into memory at a fixed location, and the processor is designed to start executing from this location after reset. Usually, it is placed on the same die as the CPU, but it can also be an external ROM chip, as is common in older systems. The boot ROM will then initialize the hardware busses and peripherals needed to boot. In some cases t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Booting
In computing, booting is the process of starting a computer as initiated via Computer hardware, hardware such as a button 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 a computer also is called Reboot (computing), 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 the operating system and some applications,Including Daemon (computing), daemons. is attained. The process of returning a computer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IBoot
iBoot is the stage 2 bootloader for all Apple products. It replaces the old bootloader, BootX. Compared with its predecessor, iBoot improves authentication performed in the boot chain. For x86 macOS, the boot process starts by running code stored in secured UEFI Boot ROM (first stage). Boot ROM has two primary responsibilities: to initialize system hardware and to select an operating system to run (the POST and UEFI component). For ARM macOS, the Boot ROM is not UEFI component. For iOS, the boot process starts by running the device's Boot ROM code. In systems with S1 processors or A9 or earlier A-series processors, the Boot ROM loads the Low-Level Bootloader (LLB), which loads iBoot. In systems with newer processors, the Boot ROM loads iBoot itself. If all goes well, iBoot will then proceed to load the iOS kernel as well as the rest of the operating system. If the LLB or iBoot fails to load iOS, or fails to verify iOS, the bootloader jumps to DFU (Device Firmware Update) mode; ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tegra
Tegra is a system on a chip (SoC) series developed by Nvidia for mobile devices such as smartphones, personal digital assistants, and mobile Internet devices. The Tegra integrates an ARM architecture central processing unit (CPU), graphics processing unit (GPU), northbridge, southbridge, and memory controller onto one package. Early Tegra SoCs are designed as efficient multimedia processors. The Tegra-line evolved to emphasize performance for gaming and machine learning applications without sacrificing power efficiency, before taking a drastic shift in direction towards platforms that provide vehicular automation with the applied "Drive" brand name on reference boards and its semiconductors; and with the "Jetson" brand name for boards adequate for AI applications within e.g. robots or drones, and for various smart high level automation purposes. History The Tegra APX 2500 was announced on February 12, 2008. The Tegra 6xx product line was revealed on June 2, 2008, and the APX ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Program Counter
The program counter (PC), commonly called the instruction pointer (IP) in Intel x86 and Itanium microprocessors, and sometimes called the instruction address register (IAR), the instruction counter, or just part of the instruction sequencer, is a processor register that indicates where a computer is in its program sequence. Usually, the PC is incremented after fetching an instruction, and holds the memory address of ("points to") the next instruction that would be executed. Processors usually fetch instructions sequentially from memory, but ''control transfer'' instructions change the sequence by placing a new value in the PC. These include branches (sometimes called jumps), subroutine calls, and returns. A transfer that is conditional on the truth of some assertion lets the computer follow a different sequence under different conditions. A branch provides that the next instruction is fetched from elsewhere in memory. A subroutine call not only branches but saves the prece ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stack Pointer
In computer science, a call stack is a stack data structure that stores information about the active subroutines of a computer program. This kind of stack is also known as an execution stack, program stack, control stack, run-time stack, or machine stack, and is often shortened to just "the stack". Although maintenance of the call stack is important for the proper functioning of most software, the details are normally hidden and automatic in high-level programming languages. Many computer instruction sets provide special instructions for manipulating stacks. A call stack is used for several related purposes, but the main reason for having one is to keep track of the point to which each active subroutine should return control when it finishes executing. An active subroutine is one that has been called, but is yet to complete execution, after which control should be handed back to the point of call. Such activations of subroutines may be nested to any level (recursive as a special ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cortex-M
The ARM Cortex-M is a group of 32-bit RISC ARM processor cores licensed by Arm Holdings. These cores are optimized for low-cost and energy-efficient integrated circuits, which have been embedded in tens of billions of consumer devices. Though they are most often the main component of microcontroller chips, sometimes they are embedded inside other types of chips too. The Cortex-M family consists of Cortex-M0, Cortex-M0+, Cortex-M1, Cortex-M3, Cortex-M4, Cortex-M7, Cortex-M23, Cortex-M33, Cortex-M35P, Cortex-M55. The Cortex-M4 / M7 / M33 / M35P / M55 cores have an FPU silicon option, and when included in the silicon these cores are sometimes known as "Cortex-Mx with FPU" or "Cortex-MxF", where 'x' is the core variant. Overview The ARM Cortex-M family are ARM microprocessor cores which are designed for use in microcontrollers, ASICs, ASSPs, FPGAs, and SoCs. Cortex-M cores are commonly used as dedicated microcontroller chips, but also are "hidden" inside of SoC chip ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CAN Bus
A Controller Area Network (CAN bus) is a robust vehicle bus standard designed to allow microcontrollers and devices to communicate with each other's applications without a host computer. It is a message-based protocol, designed originally for multiplex electrical wiring within automobiles to save on copper, but it can also be used in many other contexts. For each device, the data in a frame is transmitted serially but in such a way that if more than one device transmits at the same time, the highest priority device can continue while the others back off. Frames are received by all devices, including by the transmitting device. History Development of the CAN bus started in 1983 at Robert Bosch GmbH. The protocol was officially released in 1986 at the Society of Automotive Engineers (SAE) conference in Detroit, Michigan. The first CAN controller chips were introduced by Intel in 1987, and shortly thereafter by Philips. Released in 1991, the Mercedes-Benz W140 was the first produ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Serial Peripheral Interface
The Serial Peripheral Interface (SPI) is a synchronous serial communication interface specification used for short-distance communication, primarily in embedded systems. The interface was developed by Motorola in the mid-1980s and has become a ''de facto'' standard. Typical applications include Secure Digital cards and liquid crystal displays. SPI devices communicate in full duplex mode using a master-slave architecture usually with a single master (though some Atmel and Silabs devices support changing roles on the fly depending on an external (SS) pin). The master (controller) device originates the frame for reading and writing. Multiple slave-devices may be supported through selection with individual chip select (CS), sometimes called slave select (SS) lines. Sometimes SPI is called a ''four-wire'' serial bus, contrasting with three-, two-, and one-wire serial buses. The SPI may be accurately described as a synchronous serial interface, but it is different from the Sync ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microcontroller
A microcontroller (MCU for ''microcontroller unit'', often also MC, UC, or μC) is a small computer on a single VLSI integrated circuit (IC) chip. A microcontroller contains one or more CPUs ( processor cores) along with memory and programmable input/output peripherals. Program memory in the form of ferroelectric RAM, NOR flash or OTP ROM is also often included on chip, as well as a small amount of RAM. Microcontrollers are designed for embedded applications, in contrast to the microprocessors used in personal computers or other general purpose applications consisting of various discrete chips. In modern terminology, a microcontroller is similar to, but less sophisticated than, a system on a chip (SoC). An SoC may connect the external microcontroller chips as the motherboard components, but an SoC usually integrates the advanced peripherals like graphics processing unit (GPU) and Wi-Fi interface controller as its internal microcontroller unit circuits. Microcontrollers ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
STM32
STM32 is a family of 32-bit microcontroller integrated circuits by STMicroelectronics. The STM32 chips are grouped into related series that are based around the same 32-bit ARM processor core, such as the Cortex-M33F, Cortex-M7F, Cortex-M4F, Cortex-M3, Cortex-M0+, or Cortex-M0. Internally, each microcontroller consists of the processor core, static RAM, flash memory, debugging interface, and various peripherals. Overview The STM32 is a family of microcontroller ICs based on the 32-bit RISC ARM Cortex-M33F, Cortex-M7F, Cortex-M4F, Cortex-M3, Cortex-M0+, and Cortex-M0 cores. STMicroelectronics licenses the ARM Processor IP from ARM Holdings. The ARM core designs have numerous configurable options, and ST chooses the individual configuration to use for each design. ST attaches its own peripherals to the core before converting the design into a silicon die. The following tables summarize the STM32 microcontroller families. : History The STM32 is the third ARM family ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coreboot
coreboot, formerly known as LinuxBIOS, is a software project aimed at replacing proprietary firmware (BIOS or UEFI) found in most computers with a lightweight firmware designed to perform only the minimum number of tasks necessary to load and run a modern 32-bit or 64-bit operating system. Since coreboot initializes the bare hardware, it must be ported to every chipset and motherboard that it supports. As a result, coreboot is available only for a limited number of hardware platforms and motherboard models. One of the coreboot variants is Libreboot, a software distribution fully free of proprietary blobs, aimed at end users. History The coreboot project began in the winter of 1999 in the Advanced Computing Laboratory at Los Alamos National Laboratory (LANL), with the goal of creating a BIOS that would start fast and handle errors intelligently. It is licensed under the terms of the GNU General Public License version 2 (GPLv2). Main contributors include LANL, SiS, AMD, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
