The phrase "to the public" is a bit vague. The use of early computers was restricted mainly because of cost and size. In 1954, IBM started selling the IBM 650, the first mass produced mainframe computer. They sold over 400 in the first year of production, mainly to universities, large companies and the US Government. IBM offered to rent the computer at a cost of about $4000 per month for just the CPU and power supply (memory and card readers, used for programming were extra). You could buy the machine outright for about a half of a million dollars. Computer sales and usage continued to increase through the 1960's with sizes and prices dropping while speed and flexibility increased due to the use of transistors.
The term "Personal Computer" was first used in 1975 in reference to the Altair Microprocessor Computer Kit. It had to be assembled by the user but could be purchased for under $400. Person computers were mainly used by electronics hobbyists at this point.
In 1977 the Apple II and the Radio Shack TRS-80 personal computers were the first fully assembled units to be sold in mass quantities (thousands of units yearly) to the home market.
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