|
Zero Page (CP M)
The zero page or base page is the block of memory at the very beginning of a computer's address space; that is, the page whose starting address is zero. The size of a page depends on the context, and the significance of zero page memory versus higher addressed memory is highly dependent on machine architecture. For example, the Motorola 6800 and MOS Technology 6502 processor families treat the first 256 bytes of memory specially, whereas many other processors do not. Unlike more modern hardware, in the 1970s computer RAM was as fast as the CPU. Thus it made sense to have few registers and use the main memory as an extended pool of extra registers. In machines with a relatively wide 16-bit address bus and comparatively narrow 8-bit data bus, calculating an address in memory could take several cycles. The zero page's one-byte address was smaller and therefore faster to read and calculate than other locations, making the zero page useful for high-performance code. Zero page add ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computer
A computer is a machine that can be programmed to Execution (computing), carry out sequences of arithmetic or logical operations (computation) automatically. Modern digital electronic computers can perform generic sets of operations known as Computer program, programs. These programs enable computers to perform a wide range of tasks. A computer system is a nominally complete computer that includes the Computer hardware, hardware, operating system (main software), and peripheral equipment needed and used for full operation. This term may also refer to a group of computers that are linked and function together, such as a computer network or computer cluster. A broad range of Programmable logic controller, industrial and Consumer electronics, consumer products use computers as control systems. Simple special-purpose devices like microwave ovens and remote controls are included, as are factory devices like industrial robots and computer-aided design, as well as general-purpose devi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computer Storage
Computer data storage is a technology consisting of computer components and recording media that are used to retain digital data. It is a core function and fundamental component of computers. The central processing unit (CPU) of a computer is what manipulates data by performing computations. In practice, almost all computers use a storage hierarchy, which puts fast but expensive and small storage options close to the CPU and slower but less expensive and larger options further away. Generally, the fast volatile technologies (which lose data when off power) are referred to as "memory", while slower persistent technologies are referred to as "storage". Even the first computer designs, Charles Babbage's Analytical Engine and Percy Ludgate's Analytical Machine, clearly distinguished between processing and memory (Babbage stored numbers as rotations of gears, while Ludgate stored numbers as displacements of rods in shuttles). This distinction was extended in the Von Neuman ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Null Pointer
In computing, a null pointer or null reference is a value saved for indicating that the pointer or reference does not refer to a valid object. Programs routinely use null pointers to represent conditions such as the end of a list of unknown length or the failure to perform some action; this use of null pointers can be compared to nullable types and to the ''Nothing'' value in an option type. A null pointer should not be confused with an uninitialized pointer: a null pointer is guaranteed to compare unequal to any pointer that points to a valid object. However, depending on the language and implementation, an uninitialized pointer may not have any such guarantee. It might compare equal to other, valid pointers; or it might compare equal to null pointers. It might do both at different times; or the comparison might be undefined behaviour. C In C, two null pointers of any type are guaranteed to compare equal. The preprocessor macro NULL is defined as an implementation-define ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microsoft Windows
Windows is a group of several Proprietary software, proprietary graphical user interface, graphical operating system families developed and marketed by Microsoft. Each family caters to a certain sector of the computing industry. For example, Windows NT for consumers, Windows Server for servers, and Windows IoT for embedded systems. Defunct Windows families include Windows 9x, Windows Mobile, and Windows Phone. The first version of Windows was released on November 20, 1985, as a graphical operating system shell for MS-DOS in response to the growing interest in graphical user interfaces (GUIs). Windows is the most popular desktop operating system in the world, with Usage share of operating systems, 75% market share , according to StatCounter. However, Windows is not the most used operating system when including both mobile and desktop OSes, due to Android (operating system), Android's massive growth. , the most recent version of Windows is Windows 11 for consumer Personal compu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Linux
Linux ( or ) is a family of open-source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is typically packaged as a Linux distribution, which includes the kernel and supporting system software and libraries, many of which are provided by the GNU Project. Many Linux distributions use the word "Linux" in their name, but the Free Software Foundation uses the name "GNU/Linux" to emphasize the importance of GNU software, causing some controversy. Popular Linux distributions include Debian, Fedora Linux, and Ubuntu, the latter of which itself consists of many different distributions and modifications, including Lubuntu and Xubuntu. Commercial distributions include Red Hat Enterprise Linux and SUSE Linux Enterprise. Desktop Linux distributions include a windowing system such as X11 or Wayland, and a desktop environment such as GNOME or KDE Plasma. Distributions intended for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
FreeBSD
FreeBSD is a free and open-source Unix-like operating system descended from the Berkeley Software Distribution (BSD), which was based on Research Unix. The first version of FreeBSD was released in 1993. In 2005, FreeBSD was the most popular open-source BSD operating system, accounting for more than three-quarters of all installed and permissively licensed BSD systems. FreeBSD has similarities with Linux, with two major differences in scope and licensing: FreeBSD maintains a complete system, i.e. the project delivers a kernel, device drivers, userland utilities, and documentation, as opposed to Linux only delivering a kernel and drivers, and relying on third-parties for system software; FreeBSD source code is generally released under a permissive BSD license, as opposed to the copyleft GPL used by Linux. The FreeBSD project includes a security team overseeing all software shipped in the base distribution. A wide range of additional third-party applications may be inst ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Motorola 6809
The Motorola 6809 ("''sixty-eight-oh-nine''") is an 8-bit microprocessor with some 16-bit features. It was designed by Motorola's Terry Ritter and Joel Boney and introduced in 1978. Although source compatible with the earlier Motorola 6800, the 6809 offered significant improvements over it and 8-bit contemporaries like the MOS Technology 6502, including a hardware multiplication instruction, 16-bit arithmetic, system and user stack registers allowing re-entrant code, improved interrupts, position-independent code and an orthogonal instruction set architecture with a comprehensive set of addressing modes. Among the most powerful 8-bit processors of its era, it was also much more expensive. In 1980 a 6809 in single-unit quantities was compared to for a Zilog Z80 and for a 6502. It was launched when a new generation of 16-bit processors were coming to market, like the Intel 8086, and 32-bit designs were on the horizon, including Motorola's own 68000. It was not feature competiti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
65C816
The W65C816S (also 65C816 or 65816) is an 8/16-bit microprocessor (MPU) developed and sold by the Western Design Center (WDC). Introduced in 1985, the W65C816S is an enhanced version of the WDC 65C02 8-bit MPU, itself a CMOS enhancement of the venerable MOS Technology 6502 NMOS MPU. The 65C816 was the CPU for the Apple IIGS and, in modified form, the Super Nintendo Entertainment System. The ''65'' in the part's designation comes from its 65C02 compatibility mode, and the ''816'' signifies that the MPU has selectable 8- and 16-bit register sizes. In addition to the availability of 16-bit registers, the W65C816S features extended memory addressing to 24 bits, supporting up to 16 megabytes of random-access memory, an enhanced instruction set, and a 16 bit stack pointer, as well as several new electrical signals for improved system hardware management. At reset, the W65C816S starts in "emulation mode", meaning it substantially behaves as a 65C02. Thereafter, the W65C816S may be sw ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Western Design Center
The Western Design Center (WDC), located in Mesa, Arizona, is a company which develops intellectual property for, and licenses manufacture of, MOS Technology 65xx based microprocessors, microcontrollers (µCs), and related support devices. WDC was founded in 1978 by a former MOS Technology employee and coholder of the MOS Technology 6502 patent, Bill Mensch. Beyond discrete devices, WDC offers device designs in the form of semiconductor intellectual property cores (IP cores) to use inside other chips such as application-specific integrated circuit (ASICs), and provides ASIC and embedded systems consulting services revolving around their processor designs. WDC also produces C compilers, assembler/linker packages, simulators, development–evaluation printed circuit boards, and in-circuit emulators for their processors. Hardware products Devices Personal computer The Mensch Computer is a W65C265 and W65C22-based hobbyist experimental personal computer A personal co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Instruction Set Architecture
In computer science, an instruction set architecture (ISA), also called computer architecture, is an abstract model of a computer. A device that executes instructions described by that ISA, such as a central processing unit (CPU), is called an ''implementation''. In general, an ISA defines the supported instructions, data types, registers, the hardware support for managing main memory, fundamental features (such as the memory consistency, addressing modes, virtual memory), and the input/output model of a family of implementations of the ISA. An ISA specifies the behavior of machine code running on implementations of that ISA in a fashion that does not depend on the characteristics of that implementation, providing binary compatibility between implementations. This enables multiple implementations of an ISA that differ in characteristics such as performance, physical size, and monetary cost (among other things), but that are capable of running the same machine code, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Operand
In mathematics, an operand is the object of a mathematical operation, i.e., it is the object or quantity that is operated on. Example The following arithmetic expression shows an example of operators and operands: :3 + 6 = 9 In the above example, '+' is the symbol for the operation called addition. The operand '3' is one of the inputs (quantities) followed by the addition operator, and the operand '6' is the other input necessary for the operation. The result of the operation is 9. (The number '9' is also called the sum of the augend 3 and the addend 6.) An operand, then, is also referred to as "one of the inputs (quantities) for an operation". Notation Expressions as operands Operands may be complex, and may consist of expressions also made up of operators with operands. :(3 + 5) \times 2 In the above expression '(3 + 5)' is the first operand for the multiplication operator and '2' the second. The operand '(3 + 5)' is an expression in itself, which ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
36-bit Computing
36-bit computers were popular in the early mainframe computer era from the 1950s through the early 1970s. Starting in the 1960s, but especially the 1970s, the introduction of 7-bit ASCII and 8-bit EBCDIC led to the move to machines using 8-bit bytes, with word sizes that were multiples of 8, notably the 32-bit IBM System/360 mainframe and Digital Equipment VAX and Data General MV series superminicomputers. By the mid-1970s the conversion was largely complete, and microprocessors quickly moved from 8-bit to 16-bit to 32-bit over a period of a decade. The number of 36-bit machines rapidly fell during this period, offered largely for backward compatibility purposes running legacy programs. History Prior to the introduction of computers, the state of the art in precision scientific and engineering calculation was the ten-digit, electrically powered, mechanical calculator, such as those manufactured by Friden, Marchant and Monroe. These calculators had a column of keys for each ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
.svg "Click for more on -> Microsoft Windows"){kind=logo}
.jpg "Click for more on -> Linux")
