In computing, a data segment (often denoted .data) is a portion of an object file or the corresponding virtual address space of a program that contains initialized static variables, that is, global variables and static local variables. The size of this segment is determined by the size of the values in the program's source code, and does not change at run time.
The data segment is read-write, since the values of variables can be altered at run time. This is in contrast to the read-only data segment (rodata segment or .rodata), which contains static constants rather than variables; it also contrasts to the code segment, also known as the text segment, which is read-only on many architectures. Uninitialized data, both variables and constants, is instead in the BSS segment.
Historically, to be able to support memory address spaces larger than the native size of the internal address register would allow, early CPUs implemented a system of segmentation whereby they would store a small set of indexes to use as offsets to certain areas. The Intel 8086 family of CPUs provided four segments: the code segment, the data segment, the stack segment and the extra segment. Each segment was placed at a specific location in memory by the software being executed and all instructions that operated on the data within those segments were performed relative to the start of that segment. This allowed a 16-bit address register, which would normally provide 64KiB (65536 bytes) of memory space, to access a 1MiB (1048576 bytes) address space.
The word data has generated considerable controversy on if it is a singular, uncountable noun, or should be treated as the plural of the now-rarely-used datum.
In one sense, data is the plural form of datum. Datum actually can also be a count noun with the plural datums (see usage in datum article) that can be used with cardinal numbers (e.g. "80 datums"); data (originally a Latin plural) is not used like a normal count noun with cardinal numbers and can be plural with such plural determiners as these and many or as a singular abstract mass noun with a verb in the singular form. Even when a very small quantity of data is referenced (one number, for example) the phrase piece of data is often used, as opposed to datum. The debate over appropriate usage continues, but "data" as a singular form is far more common.
In English, the word datum is still used in the general sense of "an item given". In cartography, geography, nuclear magnetic resonance and technical drawing it is often used to refer to a single specific reference datum from which distances to all other data are measured. Any measurement or result is a datum, though data point is now far more common.
Data is a genus of moths of the Noctuidae family.
This is a list of craters on Mars. There are hundreds of thousands of impact craters on Mars, but only some of them have names. This list here only contains named Martian craters starting with the letter A – G (see also lists for H – N and O – Z).
Large Martian craters (greater than 60 km in diameter) are named after famous scientists and science fiction authors; smaller ones (less than 60 km in diameter) get their names from towns on Earth. Craters cannot be named for living people, and small crater names are not intended to be commemorative - that is, a small crater isn't actually named after a specific town on Earth, but rather its name comes at random from a pool of terrestrial place names, with some exceptions made for craters near landing sites. Latitude and longitude are given as planetographic coordinates with west longitude.
Rail 2000 (German: Bahn 2000; French: Rail 2000, Italian: Ferrovia 2000) is a large-scale project of the Swiss Federal Railways (SFR) established in 1987 to improve the quality of the Swiss rail network. It includes measures to accelerate a number of existing connections and the modernisation of rolling stock. The federal government decision to support the project in 1986 was approved by a referendum in 1987. In 2004 the first phase was completed consisting of around 130 projects with a budget of around CHF 5.9 billion.
After years of heavy investment in roads in the postwar years, the share of rail in the total passenger market in Switzerland had been significantly reduced by the end of the 1960s. At this time SFR decided that changes were necessary to increase rail patronage. More trains were operated in order to increase frequencies; this led to a 75% increase in passengers between 1971 to 1983 on the Bern–Zürich route. In the 1970s the Swiss government and SFR decided to make further improvements in rail services. In 1972, the SFR introduced a regular interval timetable (German: Taktfahrplan). Under this timetable trains arrive and leave each station at the same minute past every hour. Services at Zurich station were reorganised so that trains arrived on each line before the hour or half-hour and left after the hour or half-hour, making it easier to change to trains on other lines. This required the provision of additional platforms to allow every train to be in station simultaneously. The Rail 2000 project was intended to enhance the regular interval timetable.