Inputs to the multiplier are provided with the switch. As only eight inputs are available including clock and reset, only three bits remain available for each multiplication factor. Thus, a bit zero is set as the fourth bit. The output product is showed in the 7 segment display. Inputs are registered and a product is calculated. As output is 8-bit number, every 500ms a number appears. First the less significant 4 bits, after 500ms the most significant. When less significant 4-bits are displayed, the led dot including in the display is powered on.
HDL code is tested using Makefile and cocotb. 4 set of tests are included: the single bit adder, the 4-bit adder, the 4-bit multiplier and the top design. In real hardware, the three less significant bits can create a number times the number created with the next three bits. Reset is asserted with the seventh bit of the switch.