First thing you want to do with an unknown chip is look up the datasheet:
https://pdf1.alldatasheet.com/datasheet-pdf/view/119794/PANASONIC/MN1451B.html
Since you seem to need a general background, these chips are generally programmed with some sort of device called a programmer which puts them into programming mode and typically loads their programming memory via serial. Sometimes you can load a "boot loader" a program which handles communication so that you can load the program memory without a programmer device, though you still need some kind of interface. Any hex file built for the chip can be loaded using the device and a programmer API (computer program). Usually there is an IDE that helps you use the settings and registers of a particular type of chip, and it may support many languages which it can compile into hex for your micro controller. For example for PIC 18 chips you have several variations of embedded C such as Hitch PICC-18, MPLAB C18, Mikroe C, then theres some versions of basic, and of course you can write assembly.
Unless you have a really huge number of these the cost of your time learning to use them might be worth more than the chips are worth, and it may be better to start with a more common range of micro controllers such as PIC, AVR, propeller, LPCXpresso, PSoC (not as common, but I like them), or just an arduino board (don't need a programmer, it's a bootloaded atmel)
If you really want to go down the path of figuring these chips out I see a few things offhand. It's a 4 bit microcontroller, and I think you need an external resonator to use it. It's a Panasonic device, and it doesn't look like their modern programmers support it, but I could be wrong.