--------------------------------------------------
-- Model : 8051 Behavioral Model,
-- VHDL Entity mc8051.lo_dmem.interface
--
-- Author : Michael Mayer (mrmayer@computer.org),
-- Dr. Hardy J. Pottinger,
-- Department of Electrical Engineering
-- University of Missouri - Rolla
--
-- Created at : 09/22/98 19:32:44
--
LIBRARY ieee ;
USE ieee.std_logic_1164.all;
USE ieee.numeric_std.all;
LIBRARY mc8051 ;
USE mc8051.synth_pack.all;
ENTITY lo_dmem IS
PORT(
addr_gb : IN std_logic_vector( 7 DOWNTO 0 ) ;
int_clk : IN std_logic ;
int_rst : IN std_logic ;
rd_gb : IN std_logic ;
wr_gb : IN std_logic ;
acknow : OUT std_logic ;
data_gb : INOUT std_logic_vector( 7 DOWNTO 0 )
);
-- Declarations
END lo_dmem ;
--
-- VHDL Architecture mc8051.lo_dmem.spec
--
-- Created:
-- by - mrmayer.UNKNOWN (eeultra20.ee.umr.edu)
-- at - 22:14:24 03/29/98
--
-- Generated by Mentor Graphics' Renoir(TM) 3.0 (Build 110)
--
architecture spec of lo_dmem is
CONSTANT low_address : natural := 0;
CONSTANT high_address: natural := 127;
CONSTANT addr_width : natural := 7;
CONSTANT width : natural := 8;
SIGNAL do_write, do_read : std_logic; -- flags to command the memory
-- to perform a given action (rising edge sensitive)
SIGNAL read_data : std_logic_vector(width-1 DOWNTO 0); -- the data read
BEGIN
do_write <= '1' WHEN (addr_gb(7)='0' AND wr_gb='1') ELSE '0';
do_read <= '1' WHEN (addr_gb(7)='0' AND rd_gb='1') ELSE '0';
data_gb <= read_data WHEN do_read='1' ELSE (OTHERS => 'Z');
memory: PROCESS (do_write, do_read) IS
TYPE memory_array IS
ARRAY (natural RANGE low_address TO high_address) OF std_logic_vector(width-
1 DOWNTO 0);
VARIABLE mem: memory_array;
VARIABLE address : natural;
VARIABLE write_data: std_logic_vector(width-1 DOWNTO 0);
BEGIN
address := TO_INTEGER(unsigned(addr_gb(6 DOWNTO 0)));
IF rising_edge(do_write) THEN
mem(address) := to_X01(data_gb);
ELSIF rising_edge(do_read) THEN
read_data <= mem(address);
END IF;
END PROCESS memory;
end spec;
<div align="center"><br /><script type="text/javascript"><!--
google_ad_client = "pub-7293844627074885";
//468x60, Created at 07. 11. 25
google_ad_slot = "8619794253";
google_ad_width = 468;
google_ad_height = 60;
//--></script>
<script type="text/javascript" src="http://pagead2.googlesyndication.com/pagead/show_ads.js">
</script><br /> </div>