Question

Write a paragraph each.

Give an example of where discrete logic ICs (7400 series logic chips) are used in

industry and why.

Give an example of when you should use an FPGA instead of a PLA and explain

why. Give an example of when you should use an PLA instead of a FPGA and

explain why. Expand on the background information given in the Section

Section Overview:

The use of the logic gate integrated circuit (IC) has had several evolutions. The 7400-series logic chips were the most common digital logic devices around for many years. These chips typically contained 1 or 4 transistor-based logic gates (AND, OR, NOT, etc.), which designers would configure on a PCB to get the desired hardware equivalent to their logic design.

Most digital logic implementations have moved towards Programmable Logic Devices (PLDs). These newer devices are designed so that the user can reprogram the device configuration and/or logic by using a Hardware Description Language (HDL) instead of permanently configuring multiple chips on a circuit board.

PLDs have varying complexity, and a wide range of applications:

1. Programmable Logic Arrays (PLA) have a fixed number of hardware-defined logic gates, with configurable connections between them.
2. Complex Programmable Logic Devices (CPLD) use an HDL to program both the connections between logic gates and the logic gates themselves, giving the user more flexibility in configuring the chip.
3. Field-Programmable Gate Arrays (FPGA) are similar to CPLDs in that both the connections and the logic gates are reprogrammable, but they differ in their hardware implementation.

Answer 1

Discrete logic ICs (7400 series logic chips) includes gates like NAND (74X00), NOR (74x02), NV(74x04), buffer (74x07) AND (74x08), OR (74x32), counters, decoders, display drives and so on which are useful in digital design of traffic light control systems and other control applications in industries These logic ICs are interfaced with microcontrollers for the design of logical blocks as per the requirement. Hence, Discrete logic ICs (7400 series logic chips) can be useful in industrial applications. The controlling of direction and speed of the stepper motor using 7400 ICs and microcontrollers can be considered as an example Programmable Logic Arrays (PLAS) are generally used in the design of small and medium size circuits. These are useful for the design of combinational circuits because they may not contain data storage elements. FPGA are used to design complex circuits. FPGA contains SRAM blocks, multipliers, PLLS and other logic functions which improves the computing speed Hence for complex circuit design like Encryptions, pattern generators, FPGA is used instead of PLA

PLAS are used in the design of small and medium size circuits PLAS contain one-time programmable fuses, so these are non volatile. Hence PLAS have no power-up configuration time whereas FPGA takes time to load program into SRAM after the device is powered up. Therefore, PLAS are faster compared to FPGA particularly in the design of small and medium size circuits. Hence, for small and medium size circuits like simple Boolean function design, PLAS are used instead of FPGA The section overview describes the evolutions of ICs from basic 7400 series logic chips to the present day reprogrammable PLDS used in the logic circuit design. The section also explains the different type of PLDS (PLA, CPLD, and FPGA) based on complexity and their applications