History of Computers - Programmable Read Only Memory

Introduction

PROM (Programmable Read Only Memory), a type of ROM (Read Only Memory), stores data that does not need to be changed after installation, such as in the BIOS. PROM was invented in 1956 by Wen Tsing Chow .

Overview

PROM was designed to improve data storage and transfer for computers by making ROM more customizable. Before PROM was invented, Mask ROM dominated the market in spite of its flaws. Mask ROM could only be changed by large industrial factories, preventing individuals and small companies from accessing customized ROM. PROM enabled users to individually program their ROM, making ROM cheaper and more accessible . Wen Tsing Chow, a Chinese electrical engineer, invented PROM in 1956 while working on a project for the United States Air Force. Chow invented PROM to improve data storage in the military, but his creation significantly changed technology and computer programming world wide.

How It Works

PROM contains many bits connected to fuses. Initially, all of the bits have a value of one; however, this value can be changed to zero by burning a fuse. This process is irreversible, so a value can only be changed once. Additional PROM chips can be purchased and programmed at low cost if two distinct data values need to be stored .

Significance

PROM enables users to change the values on their own instead of requiring the manufacturer of the PROM chip to get the correct code. Before PROM, users would have to custom order the correct data sequence from the manufacturer; however, now users can alter the data without the manufacturer, reducing the cost of ROM and making it easier to obtain. PROM made computers much easier to use and program both for small companies and individuals. In addition, PROM assisted in the transition from large, corporate owned computers dominating the marked to personal computers becoming the more ubiquitous device.

External Links

[1]