IBM 5150/5155/5160 - Examples of Types of RTC Solutions
RTC = Real-Time Clock
The motherboard of the IBM 5150 (IBM PC) and IBM 5155 (IBM Portable PC) and IBM 5160 (IBM XT) contains no battery supported RTC functionality. Thus, every time that those computers are powered on, the clock in DOS defaults to 01JAN1980 00:00:00, needing to be manually set to the current date and time. The addition of RTC functionality is the fix. There were various third-party solutions made to add RTC functionality to the aforementioned computers.
All solutions require supporting software (specific to the solution).
A related diagram is at here.
Below are shown examples of each type of solution.
Card hosted RTC
RTC functionality on either a dedicated expansion card, or part of a multi-function expansion card.
Below is pictured an example; DTK's PII-126 card.
A device that sits between a ROM and the ROM's socket.
Below is pictured an example; a DS1216E Smartwatch.
Click here for details of use of a DS1216E in an IBM 5155 or IBM 5160.
A device that sits between a motherboard CPU and the CPU's socket.
Below is pictured an example; Microsync's dClock.
Floppy drive interposer
A device that sits between a floppy drive and the drive's controller.
Below is pictured an example; Microsync's dClock II.