Possibility to add support for Retro Replay cartridges

[egrath]

RR cartridges are the successor to the Action Replay ones which have increased ROM (up to 128 KiB) and RAM (32 KiB). Would it be possible to support those cartridges or are the FPGAs resources to constrained?

Attached a CRT file of RR 3.8
rr38p-tmp12.zip

[gyurco]

Carts are loaded into SDRAM, so I think it's not impossible.

[gyurco]

http://wiki.icomp.de/wiki/Retro_Replay
Some reference docs for the brave who want to implement it

[egrath]

It seems that the heavy lifting of implementing it for FPGA64 has already been done by the MISTer people, so it's maybe just a matter of copying over the necessary VHDL code - unfortunately i'm too little into FPGA development :-/

		// Retro Replay - (64k 8x8k banks + 32K RAM)
		36: begin
				IOE_ena    <= allow_freeze;
				IOF_ena    <= allow_freeze & ~reu_map;
				IOE_wr_ena <= allow_freeze & romL_we;
				IOF_wr_ena <= allow_freeze & romL_we & ~reu_map;
				bank_lo    <= ~romL_we ? bank_hi : allow_bank ? bank_hi[1:0] : 2'b00;
				IOE_bank   <= ~romL_we ? bank_hi : allow_bank ? bank_hi[1:0] : 2'b00;
				IOF_bank   <= ~romL_we ? bank_hi : allow_bank ? bank_hi[1:0] : 2'b00;

				if(nmi) allow_freeze <= 0;
				if(!init_n || freeze_crt) begin
					cart_disable  <= 0;
					exrom_overide <= 1;
					game_overide  <= 0;
					romL_we       <= 0;
					bank_lo       <= 0;
					bank_hi       <= 0;
					IOE_ena       <= 0;
					IOF_ena       <= 0;
					IOE_wr_ena    <= 0;
					IOF_wr_ena    <= 0;
					IOE_bank      <= 0;
					IOF_bank      <= 0;
					if(~init_n) begin
						exrom_overide <= 0;
						game_overide  <= 1;
						reu_map       <= 0;
						allow_bank    <= 0;
						clock_port    <= 0;
					end
				end
				else if(cart_disable) begin
					exrom_overide <= 1;
					game_overide  <= 1;
					IOE_wr_ena    <= 0;
					IOF_wr_ena    <= 0;
					IOE_ena       <= 0;
					IOF_ena       <= 0;
					romL_we       <= 0;
					allow_freeze  <= 1;
				end else begin

					if(ioe_wr & !addr_in[7:1]) begin
						bank_hi <= {data_in[7],data_in[4:3]};

						if(~addr_in[0]) begin
							cart_disable <= data_in[2];
						end
						else begin
							if(data_in[6]) reu_map    <= 1;
							if(data_in[1]) allow_bank <= 1;
							clock_port <= data_in[0];
						end

						if((data_in[6] | allow_freeze) & ~addr_in[0]) begin
							allow_freeze  <= 1;
							game_overide  <= ~data_in[0];
							exrom_overide <=  data_in[1];
							romL_we       <=  data_in[5];
						end
					end
				end
			end

[gyurco]

If you want to test, here's a build with the this patch (modified a bit).
c64_230226.zip

[egrath]

This one works great!

I've just tested the more common RR based cartridge images and they work without any flaws as far as i can tell.

Tested ones:

• Retro Replay 3.8q (The "official" one)
• Retro Replay 3.8+TMP 1.2 (with integrated Turbo Macro Pro)
• The Final Replay (RR based clone of "The Final Cartridge")

On the 3.8q i've also tested TASS which holds it's sourcecode in cartridge RAM and assembles from there. Works too:

[gyurco]

Nice, a built-in assembler.
One note that REU compatibility is currently useless, as REU is disabled if a cartridge is loaded (not all carts are REU-compatible).