had managed to get the inventory into the nation's first four storefront microcomputer retailers: Byte Shop (Palo Alto, California), itty bitty machine company (Evanston, Illinois), Data Domain (Bloomington, Indiana), and Computer Mart (New York City). The first unit produced was used in a high school math class, and donated to Liza Loop's public-access computer center. About 200 units were produced, and all but 25 were sold within nine or ten months. In April 1977, the price was dropped to . It continued to be sold through August 1977, despite the introduction of the Apple II in April 1977, which began shipping in June of that year. In October 1977, the Apple I was officially discontinued and removed from Apple's price list. As Wozniak was the only person who could answer most customer support questions about the computer, the company offered Apple I owners discounts and trade-ins for Apple IIs to persuade them to return their computers. These recovered boards were then destroyed by Apple, contributing to their rarity today. Overview Wozniak's design originally used a Motorola 6800 processor, which cost $175, but when MOS Technology introduced the much cheaper 6502 microprocessor ($25) he switched. The Apple I CPU ran at , a fraction () of the NTSC color carrier which simplified video circuitry. Memory used the new 4-Kbit DRAM chips, and was , expandable to on board, or externally. The board was designed to use the next generation of 16-Kbit memory chips when they became available. An optional $75 plug-in cassette interface card allowed users to store programs on ordinary audio cassette tapes. A BASIC interpreter, originally written by Wozniak, was provided that let users easily write programs and play simple games. An onboard AC power supply was included. The Apple I's built-in computer terminal circuitry with TV composite output used shift registers and a character generator. All one needed was a television set and a ASCII keyboard. The Apple 1 did not come with a case. It was either used as-is or some chose to build custom (mostly wooden) cases. Competing machines such as the Altair 8800 generally were programmed with front-mounted toggle switches and used indicator lights (red LEDs, most commonly) for output, and had to be extended with separate hardware to allow connection to a computer terminal or a teletypewriter machine. This made the Apple I, along with earlier introduced Sphere 1 and other hobbyist microcomputers, an