diff --git a/cpld/rtl/top.v b/cpld/rtl/top.v
index 2221ceb..949ddd4 100644
--- a/cpld/rtl/top.v
+++ b/cpld/rtl/top.v
@@ -45,6 +45,8 @@ module zx_multisound(
     output n_grom,
     output n_gram1,
     output n_gram2,
+    output n_gram3,
+    output n_gram4,
     output [18:15] gma,
 
     output dac0_out,
@@ -193,7 +195,7 @@ end
 
 /* GS INTERNAL REGISTERS */
 reg [7:0] gs_reg00, gs_reg_out;
-wire [5:0] gs_page = gs_reg00[5:0];
+wire [6:0] gs_page = gs_reg00[6:0];
 always @(posedge clk32 or negedge rst_n) begin
     if (!rst_n) begin
         gs_reg00 <= 0;
@@ -255,8 +257,17 @@ end
 
 /* GS BUS CONTROLLER */
 assign n_grom = (~n_gmreq && ((ga[15:14] == 2'b00) || (ga[15] && gs_page == 0)))? 1'b0 : 1'b1;
-assign n_gram1 = (~n_gmreq && n_grom && (~gs_page[4] || ~ga[15]))? 1'b0 : 1'b1;
-assign n_gram2 = (~n_gmreq && n_grom &&   gs_page[4] &&  ga[15] )? 1'b0 : 1'b1;
+`ifdef GS_RAM_2MB
+    assign n_gram1 = (~n_gmreq && n_grom && ((gs_page[5:4] == 2'd0) || ~ga[15]))? 1'b0 : 1'b1;
+    assign n_gram2 = (~n_gmreq && n_grom &&  (gs_page[5:4] == 2'd1) &&  ga[15] )? 1'b0 : 1'b1;
+    assign n_gram3 = (~n_gmreq && n_grom &&  (gs_page[5:4] == 2'd2) &&  ga[15] )? 1'b0 : 1'b1;
+    assign n_gram4 = (~n_gmreq && n_grom &&  (gs_page[5:4] == 2'd3) &&  ga[15] )? 1'b0 : 1'b1;
+`else
+    assign n_gram1 = (~n_gmreq && n_grom && (~gs_page[4] || ~ga[15]))? 1'b0 : 1'b1;
+    assign n_gram2 = (~n_gmreq && n_grom &&   gs_page[4] &&  ga[15] )? 1'b0 : 1'b1;
+    assign n_gram3 = 1'b1;
+    assign n_gram4 = 1'b1;
+`endif
 assign gma = (ga[15] == 1'b0)? 4'b0001 : gs_page[3:0];
 assign gd =
     (~n_giorq && ~n_grd && ga[3:0] == 4'h4)? gs_status :
diff --git a/cpld/syn/rev_A.qsf b/cpld/syn/rev_A.qsf
index b5ad762..e082849 100644
--- a/cpld/syn/rev_A.qsf
+++ b/cpld/syn/rev_A.qsf
@@ -103,6 +103,9 @@ set_location_assignment PIN_60 -to dac3_out
 set_location_assignment PIN_61 -to dac2_out
 set_location_assignment PIN_62 -to dac1_out
 set_location_assignment PIN_63 -to dac0_out
+set_location_assignment PIN_70 -to n_gram4
+set_location_assignment PIN_71 -to n_gram3
+set_location_assignment PIN_72 -to n_mreq
 set_location_assignment PIN_74 -to fm1_ena
 set_location_assignment PIN_75 -to ym_m
 set_location_assignment PIN_78 -to aa0
@@ -158,7 +161,6 @@ set_location_assignment PIN_140 -to a[8]
 set_location_assignment PIN_141 -to a[9]
 set_location_assignment PIN_142 -to a[10]
 set_location_assignment PIN_143 -to a[11]
-set_location_assignment PIN_72 -to n_mreq
 set_global_assignment -name MAX7000_OPTIMIZATION_TECHNIQUE BALANCED
 set_global_assignment -name PRE_MAPPING_RESYNTHESIS OFF
 set_global_assignment -name OPTIMIZE_HOLD_TIMING OFF
diff --git a/cpld/syn/rev_A1.qsf b/cpld/syn/rev_A1.qsf
index a5de0b6..aa88654 100644
--- a/cpld/syn/rev_A1.qsf
+++ b/cpld/syn/rev_A1.qsf
@@ -55,6 +55,7 @@ set_global_assignment -name MAX7000_DEVICE_IO_STANDARD "3.3-V LVTTL"
 set_global_assignment -name SAVE_DISK_SPACE OFF
 set_global_assignment -name TIMEQUEST_MULTICORNER_ANALYSIS OFF
 set_global_assignment -name SYNTH_TIMING_DRIVEN_SYNTHESIS OFF
+set_location_assignment PIN_1 -to n_gram4
 set_location_assignment PIN_2 -to n_gram2
 set_location_assignment PIN_5 -to gma[17]
 set_location_assignment PIN_6 -to gma[16]
@@ -159,6 +160,7 @@ set_location_assignment PIN_139 -to a[8]
 set_location_assignment PIN_140 -to a[9]
 set_location_assignment PIN_141 -to a[10]
 set_location_assignment PIN_142 -to a[11]
+set_location_assignment PIN_143 -to n_gram3
 set_global_assignment -name MAX7000_OPTIMIZATION_TECHNIQUE BALANCED
 set_global_assignment -name PRE_MAPPING_RESYNTHESIS OFF
 set_global_assignment -name OPTIMIZE_HOLD_TIMING OFF