# VHDL-VITAL

**VHDL-VITAL** or simply VITAL, *VHDL Initiative Towards ASIC Libraries*, refers to the IEEE Standard 1076.4 Timing.^{[1]}

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**VHDL-VITAL** or simply VITAL, *VHDL Initiative Towards ASIC Libraries*, refers to the IEEE Standard 1076.4 Timing.^{[1]}

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1. IEEE-488 – IEEE488 is a short-range digital communications 8-bit parallel multi-master interface bus specification. IEEE488 was created as HP-IB and is commonly called GPIB and it has been the subject of several standards. Newer standards have largely replaced IEEE488 for computer use, in the late 1960s, Hewlett-Packard manufactured various automated test and measurement instruments, such as digital multimeters and logic analyzers. They developed the HP Interface Bus to enable easier interconnection between instruments and controllers, the bus was relatively easy to implement using the technology at the time, using a simple parallel bus and several individual control lines. For example, the HP59501 Power Supply Programmer and HP 59306A Relay Actuator were both relatively simple HP-IB peripherals implemented only in TTL, using no microprocessor, HP licensed the HP-IB patents for a nominal fee to other manufacturers. It became known as the General Purpose Interface Bus, and became a de facto standard for automated, as GPIB became popular, it was formalized by various standards organizations. In 1975, the IEEE standardized the bus as Standard Digital Interface for Programmable Instrumentation, IEEE488, the standard was revised in 1987, and redesignated as IEEE488.1. These standards formalized the mechanical, electrical, and basic protocol parameters of GPIB, in 1987, IEEE introduced Standard Codes, Formats, Protocols, and Common Commands, IEEE488.2. IEEE488.2 provided for basic syntax and format conventions, as well as device-independent commands, data structures, error protocols, and the like. IEEE488.2 built on IEEE488.1 without superseding it, while IEEE488.1 defined the hardware and IEEE488.2 defined the protocol, there was still no standard for instrument-specific commands. Commands to control the same class of instrument, e. g. multimeters, the United States Air Force, and later Hewlett-Packard, recognized this problem. In 1989, HP developed their TML language which was the forerunner to Standard Commands for Programmable Instrumentation, SCPI was introduced as an industry standard in 1990. SCPI added standard generic commands, and a series of instrument classes with corresponding class-specific commands, SCPI mandated the IEEE488.2 syntax, but allowed other physical transports. The IEC developed their own standards in parallel with the IEEE, with IEC 60625-1 and IEC 60625-2, national Instruments introduced a backward-compatible extension to IEEE488.1, originally known as HS-488. It increased the maximum rate to 8 Mbyte/s, although the rate decreases as more devices are connected to the bus. This was incorporated into the standard in 2003, over HPs objections. 1/IEC 60625-1, IEEE488 is an 8-bit, electrically parallel bus. The bus employs sixteen signal lines — eight used for data transfer. Every device on the bus has a unique 5-bit primary address, the standard allows up to 15 devices to share a single physical bus of up to 20 meters total cable length

2. IEEE 754 – The IEEE Standard for Floating-Point Arithmetic is a technical standard for floating-point computation established in 1985 by the Institute of Electrical and Electronics Engineers. The standard addressed many problems found in the floating point implementations that made them difficult to use reliably and portably. Many hardware floating point units now use the IEEE754 standard, the international standard ISO/IEC/IEEE60559,2011 has been approved for adoption through JTC1/SC25 under the ISO/IEEE PSDO Agreement and published. The binary formats in the standard are included in the new standard along with three new basic formats. To conform to the current standard, an implementation must implement at least one of the formats as both an arithmetic format and an interchange format. As of September 2015, the standard is being revised to incorporate clarifications, an IEEE754 format is a set of representations of numerical values and symbols. A format may also include how the set is encoded, a format comprises, Finite numbers, which may be either base 2 or base 10. Each finite number is described by three integers, s = a sign, c = a significand, q = an exponent, the numerical value of a finite number is s × c × bq where b is the base, also called radix. For example, if the base is 10, the sign is 1, the significand is 12345, two kinds of NaN, a quiet NaN and a signaling NaN. A NaN may carry a payload that is intended for diagnostic information indicating the source of the NaN, the sign of a NaN has no meaning, but it may be predictable in some circumstances. Hence the smallest non-zero positive number that can be represented is 1×10−101 and the largest is 9999999×1090, the numbers −b1−emax and b1−emax are the smallest normal numbers, non-zero numbers between these smallest numbers are called subnormal numbers. Zero values are finite values with significand 0 and these are signed zeros, the sign bit specifies if a zero is +0 or −0. Some numbers may have several representations in the model that has just been described, for instance, if b=10 and p=7, −12.345 can be represented by −12345×10−3, −123450×10−4, and −1234500×10−5. However, for most operations, such as operations, the result does not depend on the representation of the inputs. For the decimal formats, any representation is valid, and the set of representations is called a cohort. When a result can have several representations, the standard specifies which member of the cohort is chosen, for the binary formats, the representation is made unique by choosing the smallest representable exponent. For numbers with an exponent in the range, the leading bit of the significand will always be 1. Consequently, the leading 1 bit can be implied rather than explicitly present in the memory encoding and this rule is called leading bit convention, implicit bit convention, or hidden bit convention