Introduction to digital ICs 2716

Definition

The 2716 IC is a 16 Kbit EPROM organized as 2,048 words × 8 bits and used to store digital information non-volatilely. It is a memory chip whose contents can be electrically programmed and later erased by exposure to ultraviolet light through a quartz window on the package.

In simpler terms, the 2716 is a chip that:

remembers data even when power is off

can be programmed once or many times after erasure
provides 8-bit output data for each selected memory address

Main Content

1. First Concept: Structure and Organization of the 2716

The 2716 is organized as 2048 memory locations, each storing 8 bits of data. This means it has a total capacity of 2 KB.
It uses address lines to select one location at a time and data lines to read out or write in the 8-bit information.

The chip is usually packaged in a 24-pin dual-in-line package (DIP). Its main pins include:

Address inputs

: A0 to A10

Data outputs

: D0 to D7

Control pins

: such as CE (Chip Enable), OE (Output Enable), and programming-related pins

A simplified memory organization view:

Address lines (A0–A10)
        |
        v
+----------------------+
|      2716 EPROM      |
|  2048 x 8 memory     |
+----------------------+
        |
        v
Data lines (D0–D7)

Because there are 11 address lines, the number of possible locations is:

2^11 = 2048 locations

Each address points to one 8-bit word, so the total memory size is:

2048 × 8 = 16384 bits = 16 Kbits = 2 KB

This organization makes the 2716 suitable for storing small programs, machine code, and fixed data tables.

2. Second Concept: EPROM Nature and Non-Volatile Storage

The 2716 is an EPROM, meaning it is programmable and erasable using ultraviolet light.
Unlike RAM, it is non-volatile, so the stored data remains intact even after power is removed.

This makes the 2716 very useful in systems where program memory must be retained permanently. Its memory cells are built using floating-gate transistors, which trap charge. The presence or absence of charge represents a binary state.

Key characteristics of EPROM behavior:

Programming

: electrical pulses are used to store data

Retention

: data stays stored for years

Erasure

: UV light clears the entire chip

Reprogramming

: after erasure, the chip can be programmed again

A typical EPROM package includes a transparent quartz window so that ultraviolet light can reach the silicon memory cells.

Example:

A microcontroller-based instrument may use the 2716 to store its startup instructions.
When power is switched off, the firmware remains safe in the chip.
If the firmware must be changed, the chip is removed, erased with UV light, and programmed again.

This feature was especially valuable in the early stages of digital system development.

3. Third Concept: Operation in Sequential Logic Systems

The 2716 is important in sequential logic because it stores information that depends on previous programming, making it a state-retaining digital device.
It acts as a memory element in larger sequential systems, especially in microprocessor-based designs.

In sequential logic, outputs depend on:

current inputs
current internal state
previously stored data

The 2716 contributes to this concept by acting as a fixed memory block. For example, a processor reads instructions from the 2716 one address at a time. The output of the chip changes as the address changes, but the contents at each address remain stored until erased.

Basic read operation idea:

CPU puts address on A0–A10
          |
          v
     +---------+
     |  2716   |
     +---------+
          |
          v
  Output data on D0–D7

Important control signals:

CE (Chip Enable)

: activates the chip

OE (Output Enable)

: allows data to appear on output pins
If either is inactive, outputs may be disabled

This sequential reading of memory locations is the basis of how stored programs are executed in digital computers.

Working / Process

1. Address selection

The external system, such as a CPU or tester, places a binary address on the address lines A0 to A10.
This selects one specific memory location from the 2048 available locations.

2. Data retrieval or programming

During a read operation, the selected memory word appears on D0 to D7 when CE and OE are active.
During a programming operation, data is written into the cell using appropriate programming voltage and timing conditions.
During erasure, the chip is exposed to ultraviolet light for a specified time, which clears all stored data.

3. Output response

After access time, the chip outputs stable 8-bit data corresponding to the selected address.
The data remains valid as long as the control signals allow it and the address is unchanged.

Example read cycle:


1. Put address 00010100110 on A0–A10
2. Enable CE and OE
3. Read 8-bit data from D0–D7

In practical use, this process is repeated continuously as the processor fetches instructions or lookup values from memory.

Advantages / Applications

Non-volatile storage

: retains data without power, making it ideal for firmware and fixed program storage.

Easy reprogramming after erasure

: can be erased with UV light and reused, which was cost-effective in development stages.

Reliable in digital systems

: widely used for program memory, control tables, and embedded system code in early electronics.

Common applications of the 2716 include:

storing boot programs
storing microprocessor instructions
holding lookup tables
use in educational digital logic experiments
use in early embedded systems and control units

It was especially useful when designers needed permanent memory that could still be updated during prototyping.

Summary

The 2716 is a 2 KB EPROM used to store digital data permanently until erased with ultraviolet light.
It works as a non-volatile memory IC in sequential logic systems by holding stored information across power cycles.
It is useful for program storage, lookup tables, and embedded control memory.

Important terms to remember

: EPROM, non-volatile, address lines, data lines, chip enable, output enable, UV erasure