Wikipedia
The 12-bit PDP-8, produced by Digital Equipment Corporation (DEC), is the first successful commercial minicomputer. DEC introduced it on March 22, 1965 priced at 18,500 US$, equivalent to US$ today, and eventually sold more than 50,000 systems, the most of any computer up to that time. The PDP-8 was the first computer to be sold for under $20,000 and then DEC sold the PDP-8/S for under 10,000. It was the first widely sold computer in the DEC PDP series of computers (the PDP-5 was not originally intended to be a general-purpose computer). The chief engineer who designed the initial version of the PDP-8 was Edson de Castro, who later founded Data General.
The earliest PDP-8 model (informally known as a "Straight-8") used diode-transistor logic, packaged on flip chip cards, and was about the size of a small household refrigerator.
This was followed in 1966 by the PDP-8/S, available in desktop and rack-mount models. By using a one-bit serial arithmetic logic unit (ALU) implementation, the PDP-8/S was smaller, less expensive and slower than the original PDP-8. The PDP-8/S was about 20% of the cost and about 10% of the performance of the PDP-8. The only mass storage peripheral available for the PDP-8/S was the DF32 disk.
Later systems (the PDP-8/I and /L, the PDP-8/E, /F, and /M, and the PDP-8/A) returned to a faster, fully parallel implementation but used much less costly transistor-transistor logic (TTL) MSI logic. Most surviving PDP-8s are from this era. The PDP-8/E is common, and well-regarded because so many types of I/O devices were available for it. It was often configured as a general-purpose computer.
In 1975, early personal computers based on inexpensive microprocessors, such as the MITS Altair 8800 and later TRS-80, Apple II and others began to dominate the market for small general purpose computers.
The last commercial PDP-8 models in 1979 were called "CMOS-8s" and used custom complementary metal-oxide-semiconductor ( CMOS) microprocessors. They were not priced competitively, and the offering failed. The IBM PC in 1981 cemented the doom of the CMOS-8s by making a legitimate, well-supported small microprocessor computer.
Intersil sold the integrated circuits commercially through to 1982 as the Intersil 6100 family. By virtue of their CMOS technology they had low power requirements and were used in some embedded military systems.