Here are 3 ways to make a clock using a C8051:
1.) Use a 8051 and a 1 line LCD display. The LCD connects to the 8051 using the SPI or I2C bus
This is the most expensive and it can be hard to connect to the LCD without a PCB
2.) Use 4 7 segment displays connected to the 8051's GPIO pins.
This is a little less expensive and can be wire wrapped or hand soldered
3.) My favorite and one I use for training classes:
Use a 8051 and use GPIO pins to drive 16 LEDs. I think blue LEDs look the best but any will work.
This is the least expensive and can be added to any C8051 eval board.
The clock looks like this:
This is the time I wrote the post. If you can read binary you will see it was 02:59. The red LEDs can be hook to power and stay on all of the time or you can use another GPIO and have them flash once a second.
If you need help with any approach let me know.