What is a Programmable Chip?

The full name of programmable logic device in English is: programmable logic device or PLD. PLD is produced as a general-purpose integrated circuit, and its logic function is determined according to the user's programming of the device. The integration level of general PLD is high enough to meet the needs of designing general digital systems.

This allows a designer to program

1970s: Programmable Read Only Memory (PROM), Programmable Logic Array (PLA)

Late 1970s: AMD introduced Programmable Array Logic (PAL)

1980s: Lattice company introduced Generic Array Logic

Mid 80's: Xilinx Company introduced Field Programmable Gate Array FPGA (Field Programmable GateArray). Altera has introduced the EPLD (Erase Programmable Logic Device), which is highly integrated, flexible in design, and can be programmed repeatedly.

Early 90's: Lattice company also introduced in-system programmable concept ISP and its in-system programmable large-scale integrated device ispLSI)

Now Xilinx, Altera, Lattice are the main manufacturers. The FPGAs produced can reach tens of millions of gates, the speed can be 550MHz, and 65nm or higher lithography technology is used. ^[1]

Logic devices can be divided into two categories-fixed logic devices and programmable logic devices. As the name implies, the circuits in fixed logic devices are permanent and they perform a function or set of functions-once manufactured, they cannot be changed. Programmable logic devices (PLDs), on the other hand, are standard off-the-shelf components that provide customers with a wide range of logic capabilities, characteristics, speeds, and voltage characteristics-and such devices can be changed at any time to accomplish many different Functions.

For fixed logic devices, depending on the complexity of the device, the time required from design, prototype, to final production can range from months to more than a year. Moreover, if the device does not work properly, or if application requirements change, then a completely new design must be developed. The up-front work to design and verify fixed logic requires a lot of "non-recurring engineering costs," or NREs. NRE means that in the fixed logic device finally from the chip

PLD has programmable read-only memory (PROM), erasable programmable memory (EPROM), programmable logic array (PLA for short), programmable array logic (PAL for short), and general array logic (for short GAL). Their structural features and functions are listed in the table.

The overall structure of PLA is similar to PROM, and it also consists of AND gate array, OR gate array and output buffer; its AND gate array is programmable. When generating the same combination of logic functions, using PLA saves the number of cells in the AND gate array and OR gate array than using PROM.

Some PAL devices have a register output structure, so PAL can not only form a combination logic circuit, but also a sequential logic circuit. The output macro logic unit of the GAL has different working modes and allows selection through programming. These operating modes include various output structures for PAL. GAL is more versatile. The programming work of PAL and GAL is more complicated, and it needs to use special development tools (including programmer and programming language). These development tools are easy to use.

Fixed logic devices and PLDs each have their own advantages. For example, fixed

Over the past few years, programmable logic vendors have made tremendous technological progress, so that PLD is considered by many designers as the logical choice for logic solutions. One of the important reasons for this is that PLD suppliers like Xilinx are "fabless" companies and do not directly own chip manufacturing plants. Xilinx outsources chip manufacturing to major businesses such as IBM Microelectronics and UMC Is the partner that makes the chip. This strategy allows Xilinx to focus on designing new product structures,

Programming language

Regarding the "PAL" mentioned earlier, it is too complicated to manually generate JEDEC files, so most of them use computer programs (also called: computer programs) to generate them. Such programs (programs) are called " "Logic compiler", which is similar to the software compiler used in program development and writing. To compile the original source code (also called: source code), you must use a specific programming language (also called: programming language, Programming language), this is called hardware description language (hardware description language), referred to as: HDL.

Moreover, there is not only one type of HDL, but many types, such as ABEL, AHDL, Confluence, CUPL, HDCal, JHDL, Lava, Lola, MyHDL, PALASM, RHDL, etc., but the most well-known and most commonly used are VHDL and Verilog.