Questions tagged [rtc]

Timekeeping hardware that maintains the current wall-clock time, its hardware interface and batteries that maintain its state.

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15
votes
4answers
2k views

How was the real-time clock implemented in the original IBM PC and PC/XT?

I know that the IBM PC/AT added a battery backed real-time clock chip that independently maintained time whether the system was powered or not. I've also seen many of those big DS1287 clock chips on ...
4
votes
1answer
122 views

Quadram odd IBM PC card bracket

I came across an early IBM PC ISA realtime clock/calendar card made by Quadram called the "Chronograph" (picture). It's basically the same clock feature they incorporated into their ...
2
votes
1answer
156 views

Did the RTC in certain cartridges get power over the GBA bus?

Some GBA games, like Pokemon Ruby, contained an internal RTC with a small button battery to power it. When the cartridges were inserted and the GBA was powered on, did the RTC continue to run on the ...
26
votes
3answers
6k views

Why does DOS ask for the current date and time upon booting?

In most versions of DOS, when they are started from a medium that lacks an AUTOEXEC.BAT file, the very first thing COMMAND.COM does is ask the user to confirm the current date and time: Starting PC ...
1
vote
2answers
369 views

Performing 16-bit port I/O on the RTC

Why can’t the RTC (0x70, 0x71) read and write 16 bits at a time? For example: mov ax, 0xa8f out 0x70, ax I have found in a 286 BIOS that did this (BIOS ID string: S286-6181-...
2
votes
1answer
179 views

Can I change laptop's RTC and backup battery with generic Ni-MH?

I got old Toshiba 100CS for a good price. After some inspection, I noticed that AutoResume backup battery and RTC battery are already gone bad, and seems can't hold charge. I've checked eBay for ...
12
votes
3answers
666 views

Will using a clockport RTC card on an Amiga 1200 clash with the RTC on an accelerator card?

I have an accelerator card fitted to my Amiga 1200. The accelerator includes a real-time clock, but I noticed that the soldered-on rechargeable battery was in danger of leaking, so I cut it off before ...