Apple Computer started mass production on the Apple 2 series of computers in 1977. The Apple ][ had and 8-bit 6502 processor and ran at a blazing 1megahertz which by today's standards is insanely slow. Early Apple 2+ machines came with only 4k yet it was more standard to have 48k. Microsoft even produced a 16k expansion card pushing the amount of memory up to 64k.
Apple soon started producing the Apple 2e (or Enhanced) which was an identical machine only it came with 64k standard memory, upper and lower case character set and a bit of a different keyboard layout. Another signicificant change was the drop in total number of chips on the board inside the box. Also the price of the Apple 2e was a bit lower from that of the Apple 2+.
Apple also introduced the Apple 2c which came with 128k standard a 3.5" floppy drive built into the machine and looked like a very large laptop.
By the time that Apple Computer stopped manufacturing the Apple 2 seires of computers they had sold 2 million of them.
The machine has even been called the greatest PC of all times by PC World magazine http://www.pcworld.com/article/id,126692-page,10-c,systems/article.html#II