PDP，是DEC公司生产的小型机系列的代号。PDP是“Programmed Data Processor”（进程数据处理机）的首字母缩写。

在计算机发展的初期，整个计算机产业就已发展到了相当的规模，但是计算机只有一些资金雄厚的公司和机构才能用的起，因为那时的计算机都是庞然大物，功能强大而复杂（当然不能与现代计算机相比）。

1960年，DEC推出了首个以阴极管为监视器的小型机产品PDP-1设备。PDP-1简化了大型机的功能，而且价格低廉。1965年推出了世界上第一台真正意义的小型计算机PDP-8。随后，DEC又推出了世界上首款采用晶体管的小型机PDP-8/1。1970年，DEC推出了第一款 16位小型机PDP-11。（美国工业协会评为“70年代最具影响力的技术产品”）。

Programmed Data Processor (PDP) was a series of minicomputers made and marketed by the Digital Equipment Corporation from 1957 to 1990. The name "PDP" intentionally avoided the use of the term "computer" because, at the time of the first PDPs, computers had a reputation of being large, complicated, and expensive machines, and the venture capitalists behind Digital (especially Georges Doriot) would not support Digital's attempting to build a "computer"; the word "minicomputer" had not yet been coined. So instead, Digital used their existing line of logic modules to build a Programmed Data Processor and aimed it at a market that could not afford the larger computers.