clk clk clk_fast clk_fast tick_reg tick_reg tick_fast_reg[6:0] tick_fast_reg[6:0] tick_last_fast_reg tick_last_fast_reg atari_bus_request atari_bus_request sram_drive_data sram_drive_data ext_sram_addr[19:0] ext_sram_addr[19:0] ext_sram_data[7:0] ext_sram_data[7:0] ext_sram_oe ext_sram_oe ext_sram_we ext_sram_we sram_we_n sram_we_n