$ whois vhdl

VHDL

first released in 1987 · by United States Department of Defense

$ guessprog --inspect vhdl

year: 1987
paradigm: declarative
family: pascal
memory: none
binding: static
safety: strong

VHDL(7)

AUTHORS: United States Department of Defense
HISTORY: VHDL, the VHSIC Hardware Description Language, was born in the early 1980s from the US Department of Defense's Very High Speed Integrated Circuit programme, with Intermetrics, IBM and Texas Instruments doing the language development. Its first purpose was to document the behaviour of the custom chips that suppliers delivered to the military, replacing huge and inconsistent paper manuals. Soon simulators and then synthesis tools were built to turn these descriptions into real hardware. Its syntax borrows heavily from Ada, and it became the IEEE 1076 standard in 1987.
USAGE: One of the two dominant hardware description languages, alongside Verilog, used to design FPGAs and ASICs. It is especially common in Europe and in the aerospace and defence industries, and is taught in many electronics engineering courses.
SEE ALSO: VHDL on Wikipedia ↗

$ cat counter.vhd

library ieee;
use ieee.std_logic_1164.all, ieee.numeric_std.all;

entity counter is
  port (clk, rst : in std_logic; q : buffer unsigned(3 downto 0));
end entity;

architecture rtl of counter is
begin
  process (clk) begin
    if rising_edge(clk) then
      if rst = '1' then q <= (others => '0');
      else q <= q + 1;
      end if;
    end if;
  end process;
end architecture;