-- 65xx compatible microprocessor core
--
-- Copyright (c) 2002...2015
-- Daniel Wallner (jesus <at> opencores <dot> org)
-- Mike Johnson (mikej <at> fpgaarcade <dot> com)
-- Wolfgang Scherr (WoS <at> pin4 <dot> at>
-- Morten Leikvoll ()
--
-- All rights reserved
--
-- Redistribution and use in source and synthezised forms, with or without
-- modification, are permitted provided that the following conditions are met:
--
-- Redistributions of source code must retain the above copyright notice,
-- this list of conditions and the following disclaimer.
--
-- Redistributions in synthesized form must reproduce the above copyright
-- notice, this list of conditions and the following disclaimer in the
-- documentation and/or other materials provided with the distribution.
--
-- Neither the name of the author nor the names of other contributors may
-- be used to endorse or promote products derived from this software without
-- specific prior written permission.
--
-- THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
-- AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
-- THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
-- PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE
-- LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
-- CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
-- SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
-- INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
-- CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
-- ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
-- POSSIBILITY OF SUCH DAMAGE.
--
-- Please report bugs to the author(s), but before you do so, please
-- make sure that this is not a derivative work and that
-- you have the latest version of this file.
--
-- ----- IMPORTANT NOTES -----
--
-- Limitations:
-- 65C02 and 65C816 modes are incomplete (and definitely untested after all 6502 undoc fixes)
-- 65C02 supported : inc, dec, phx, plx, phy, ply
-- 65D02 missing : bra, ora, lda, cmp, sbc, tsb*2, trb*2, stz*2, bit*2, wai, stp, jmp, bbr*8, bbs*8
-- Some interface signals behave incorrect
-- NMI interrupt handling not nice, needs further rework (to cycle-based encoding).
--
-- Usage:
-- The enable signal allows clock gating / throttling without using the ready signal.
-- Set it to constant '1' when using the Clk input as the CPU clock directly.
--
-- TAKE CARE you route the DO signal back to the DI signal while R_W_n='0',
-- otherwise some undocumented opcodes won't work correctly.
-- EXAMPLE:
-- CPU : entity work.T65
-- port map (
-- R_W_n => cpu_rwn_s,
-- [....all other ports....]
-- DI => cpu_din_s,
-- DO => cpu_dout_s
-- );
-- cpu_din_s <= cpu_dout_s when cpu_rwn_s='0' else
-- [....other sources from peripherals and memories...]
--
-- ----- IMPORTANT NOTES -----
--
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