In
electronics
The field of electronics is a branch of physics and electrical engineering that deals with the emission, behaviour and effects of electrons using electronic devices. Electronics uses active devices to control electron flow by amplification ...
, glue logic is the custom
logic circuitry used to interface a number of
off-the-shelf
Off-the-shelf may refer to:
* Commercial off-the-shelf, a phrase in computing and industrial supply terminology
* Government off-the-shelf
* Ready-to-wear
* Shelf corporation, a type of company
* Off the Shelf Festival, a festival of writing and r ...
integrated circuits.
This is often achieved using common, inexpensive
7400- or
4000 4000 or ''variation'', may refer to:
* 4000 (number)
* 4000 BCE, a year in the 4th millennium BC
* A.D. 4000, the last year of the 4th millennium CE, a century leap year starting on Saturday
* 4000s AD, a decade, century, millennium in the 5th mill ...
-series components. In more complex cases, a
programmable logic device
A programmable logic device (PLD) is an electronic component used to build reconfigurable digital circuits. Unlike digital logic constructed using discrete logic gates with fixed functions, a PLD has an undefined function at the time of man ...
like a
CPLD or
FPGA
A field-programmable gate array (FPGA) is an integrated circuit designed to be configured by a customer or a designer after manufacturinghence the term ''Field-programmability, field-programmable''. The FPGA configuration is generally specifi ...
might be used. The falling price of programmable logic devices, combined with their reduced size and power consumption compared to discrete components, is making them common even for simple systems. In addition, programmable logic can be used to hide the exact function of a circuit, in order to prevent a product from being
cloned or counterfeited.
The software equivalent of glue logic is called
glue code.
Usage
Typical functions of glue logic may include:
*
Simple logic functions.
*
Address decoding circuitry used with older processors like the
MOS Technology 6502
The MOS Technology 6502 (typically pronounced "sixty-five-oh-two" or "six-five-oh-two") William Mensch and the moderator both pronounce the 6502 microprocessor as ''"sixty-five-oh-two"''. is an 8-bit microprocessor that was designed by a small te ...
or
Zilog Z80
The Z80 is an 8-bit computing, 8-bit microprocessor introduced by Zilog as the startup company's first product. The Z80 was conceived by Federico Faggin in late 1974 and developed by him and his 11 employees starting in early 1975. The first wor ...
to divide up the processor's address space into RAM, ROM and I/O. Newer versions of these processors, such as the
WDC 65816 or the
Zilog eZ80, may add features that enable glueless interfacing to external devices.
*Buffers to protect outputs from overload, or protect sensitive inputs from
electrostatic discharge
Electrostatic discharge (ESD) is a sudden and momentary flow of electric current between two electrically charged objects caused by contact, an electrical short or dielectric breakdown. A buildup of static electricity can be caused by tribochar ...
damage.
*Voltage level conversion, ''e.g.'', when interfacing one logic family (
CMOS) to another (
TTL).
See also
*
Glue code
*
Reverse engineering
Reverse engineering (also known as backwards engineering or back engineering) is a process or method through which one attempts to understand through deductive reasoning how a previously made device, process, system, or piece of software accompli ...
References
Electrical circuits
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