Programmable Logical Devices
In an era of technological advancement, innovations like computers, smartphones and tablets contain some components that are electronic or digital integrated circuits which one can configure/program using a hardware description language such as VHDL(VHSIC Hardware Description Language), CUPL, ADA or Verilog among others. These components are referred to as programmable devices.With the correct tools you can even generate a schematic that is used to build the file that will be used to program the device.
There are several types of programmable logic available. Older versions like the programmable array logic (PAL) such as the PAL20R8, the generic array logic (GAL) such as the GAL22v10, the programmable logic device (PLD) such as the 22V10, the simple programmable logic device (SPLD) such as the 20V8 have been around for quite some time.
The complex programmable logic device (CPLD) such as the XC2C32A from Xilinx, and the field programmable gate array (FPGA) such as the XC3S50 from Xilinx are some of the newer versions of programmable logic that are a result of improvements to the original types of devices.The term “field-programmable” means the device is programmed by the customer, not the manufacturer.
A PLD is a combination of a logic device and a memory device. The memory is used to store the pattern that was given to the chip during programming. Most of the methods for storing data in an integrated circuit have been adapted for use in PLDs. These include:
- Silicon anti fuses
- EPROM or EEPROM cells
- Flash memory
Programming devices could be found specifically in bus interfaces, decoders , counters e.t.c.
These are electronic in nature with I/O lines; with supply voltages; with memory density; system gates; and so on.
Devices that are programmable do not have a defined function when manufactured, so it can be reprogrammed even after a piece of equipment is shipped to a customer. A number of equipment manufacturers now tout the ability to add new features or upgrade products that already are in the field by simply uploading a new programming file to the Programming Device, via the Internet, creating new hardware logic in the system. So, in this light, programmable devices saves cost, time and resources.