UPD4990: Difference between revisions
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The uPD4990 is a Real Time Clock (RTC) chip made by NEC, to keep the [[calendar]]'s time and date informations on MVS boards. | The uPD4990 is a Real Time Clock (RTC) chip made by NEC, to keep the [[calendar]]'s time and date informations on MVS boards. | ||
It shared the [[ | It shared the [[battery-backed RAM]]'s battery and had a separate 32.768kHz crystal clock to run when power was off. | ||
==Datasheet== | |||
Official uPD4990A datasheet: [[http://www.datasheetcatalog.org/datasheet/nec/UPD4990AC.pdf]] | |||
[[Category:Chips]] | [[Category:Chips]] | ||
Revision as of 22:00, 6 March 2011
The uPD4990 is a Real Time Clock (RTC) chip made by NEC, to keep the calendar's time and date informations on MVS boards.
It shared the battery-backed RAM's battery and had a separate 32.768kHz crystal clock to run when power was off.
Datasheet
Official uPD4990A datasheet: [[1]]