Peripheral Interface Adapter: Difference between revisions

Revision as of 08:23, 10 June 2019

Revision as of 01:50, 4 May 2020

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In 1976 Motorola switched the MC6800 family to a depletion-mode technology to improve the manufacturing yield and to operate at a faster speed. The Peripheral Interface Adapter had a slight change in the electrical characteristics of the I/O pins so the MC6820 became the MC6821.<ref name = "MC6821">{{Cite book | title = Advanced Information: 1.5 and 2.0 MHz Components for the M6800 Microcomputer System. | pages = 4–6 | publisher = Motorola Semiconductor Products | ___location = Austin, Texas | date = April 1977 | id = ADI-429}} The MC6820 became the MC6821 because the electrical characteristic of PA0–7 and PB0–7 pins changed slightly. The typical Input High Current went from -250 μAdc to -400 μAdc and the Input Low Current went from 1.0 mAdc to 1.3 mAdc.</ref>

The MC6820 was used in the Apple I to interface the ASCII keyboard and the display.<ref>{{Cite book | title = Apple-1 Operation Manual | page = 7 | date = 1976 | url = http://archive.computerhistory.org/resources/text/Apple/Apple.AppleI.1976.102646518.pdf | access-date = 2016-03-05 | archive-url = https://web.archive.org/web/20110519052739/http://archive.computerhistory.org/resources/text/Apple/Apple.AppleI.1976.102646518.pdf | archive-date = 2011-05-19 | url-status = dead }}</ref>

The MC6820 was used in the Apple I to interface the ASCII keyboard and the display.<ref>

{{Cite book | title = Apple-1 Operation Manual | page = 7 | date = 1976 | url=http://archive.computerhistory.org/resources/text/Apple/Apple.AppleI.1976.102646518.pdf}}</ref>

It was also deployed in the 6800-powered first generation of Bally electronic pinball machines (1977-1985), such as Flash Gordon<ref>

{{Cite book | title = Flash Gordon Manual | page = 22 | date = 1981| publisher = Bally | url = http://www.ipdb.org/machine.cgi?id=874}}</ref>