diff --git a/20display_num.asm b/20display_num.asm
new file mode 100644
index 0000000..ce755f5
--- /dev/null
+++ b/20display_num.asm
@@ -0,0 +1,139 @@
+.text
+    #initialize $sp
+    lui     $sp,            0x4000
+    addi    $sp,            $sp,                    0x7ff
+
+    # load digit to mem
+    lui     $s0,            0x4000
+    addi    $s0,            $s0,                    0x20
+    #0
+    addi    $s1,            $zero,                  0x3f
+    sw      $s1,            0($s0)
+    #1
+    addi    $s1,            $zero,                  0x6
+    sw      $s1,            4($s0)
+    #2
+    addi    $s1,            $zero,                  0x5b
+    sw      $s1,            8($s0)
+    #3
+    addi    $s1,            $zero,                  0x4f
+    sw      $s1,            12($s0)
+    #4
+    addi    $s1,            $zero,                  0x66
+    sw      $s1,            16($s0)
+    #5
+    addi    $s1,            $zero,                  0x6d
+    sw      $s1,            20($s0)
+    #6
+    addi    $s1,            $zero,                  0x7d
+    sw      $s1,            24($s0)
+    #7
+    addi    $s1,            $zero,                  0x7
+    sw      $s1,            28($s0)
+    #8
+    addi    $s1,            $zero,                  0x7f
+    sw      $s1,            32($s0)
+    #9
+    addi    $s1,            $zero,                  0x6f
+    sw      $s1,            36($s0)
+    #A
+    addi    $s1,            $zero,                  0x77
+    sw      $s1,            40($s0)
+    #B
+    addi    $s1,            $zero,                  0x7c
+    sw      $s1,            44($s0)
+    #C
+    addi    $s1,            $zero,                  0x58
+    sw      $s1,            48($s0)
+    #D
+    addi    $s1,            $zero,                  0x5e
+    sw      $s1,            52($s0)
+    #E
+    addi    $s1,            $zero,                  0x79
+    sw      $s1,            56($s0)
+    #F
+    addi    $s1,            $zero,                  0x71
+    sw      $s1,            60($s0)
+
+    lui     $s1,            0x4000
+    addi    $s1,            $s1,                    0x10
+    addi    $s0,            $zero,                  0xa80
+main_loop:
+    addi    $s0,            $s0,                    1
+    addi    $a0,            $s0,                    0
+    addi    $a1,            $s1,                    0
+    jal     display_number
+    j       main_loop
+
+
+    # a0 is the number to be displayed, a1 is the bcd control addr
+display_number:
+    addi    $sp,            $sp,                    -32
+    sw      $ra,            4($sp)
+    sw      $s0,            8($sp)
+    sw      $s1,            12($sp)
+    sw      $s2,            16($sp)
+    sw      $s3,            20($sp)
+    sw      $s4,            24($sp)
+    sw      $s5,            28($sp)
+    sw      $s6,            32($sp)
+
+    # s0 is the number to be displayed
+    addi    $s0,            $a0,                    0
+
+    # s1 is the bcd_control addr
+    addi    $s1,            $a1,                    0
+
+    # s2 is the base addr for display digit
+    lui     $s2,            0x4000
+    addi    $s2,            $s2,                    0x20
+
+    # s3 is the counter for a complete scan of 4 digit
+    addi    $s3,            $zero,                  0x2ed4
+all_digit_scan_loop:
+    # s4 is the num being shifted gradually
+    addi    $s4,            $s0,                    0
+    # s6 is the enable digit
+    addi    $s6,            $zero,                  0x100
+
+    addi    $s5,            $zero,                  4
+single_digit_loop:
+    # get a digit
+    andi    $t0,            $s4,                    0xf
+    # digit * 4 is the memory shift
+    sll     $t0,            $t0,                    2
+    add     $t0,            $s2,                    $t0
+    lw      $t0,            0($t0)
+    or      $t0,            $t0,                    $s6
+    sw      $t0,            0($s1)
+
+    srl     $s4,            $s4,                    4
+    sll     $s6,            $s6,                    1
+    # jal     wait_for_digit_time
+
+    addi    $t0,            $zero,                  0x00ff
+wait_time_loop:
+    addi    $t0,            $t0,                    -1
+    bgtz    $t0,            wait_time_loop
+
+    addi    $s5,            $s5,                    -1
+    bgtz    $s5,            single_digit_loop
+    # end of single digit loop
+    
+    # ** depends on the clock **
+    # four digit, 83.42us. 
+    # 1s / 83.42us = 11988 = (2ed4)hex
+
+    addi    $s3,            $s3,                    -1
+    bgtz    $s3,            all_digit_scan_loop
+
+    lw      $ra,            4($sp)
+    lw      $s0,            8($sp)
+    lw      $s1,            12($sp)
+    lw      $s2,            16($sp)
+    lw      $s3,            20($sp)
+    lw      $s4,            24($sp)
+    lw      $s5,            28($sp)
+    lw      $s6,            32($sp)
+    addi    $sp,            $sp,                    32
+    jr      $ra
diff --git a/20display_num.txt b/20display_num.txt
new file mode 100644
index 0000000..d6276e3
--- /dev/null
+++ b/20display_num.txt
@@ -0,0 +1,86 @@
+20'd0: instruction <= 32'h3c1d4000;
+20'd1: instruction <= 32'h23bd07ff;
+20'd2: instruction <= 32'h3c104000;
+20'd3: instruction <= 32'h22100020;
+20'd4: instruction <= 32'h2011003f;
+20'd5: instruction <= 32'hae110000;
+20'd6: instruction <= 32'h20110006;
+20'd7: instruction <= 32'hae110004;
+20'd8: instruction <= 32'h2011005b;
+20'd9: instruction <= 32'hae110008;
+20'd10: instruction <= 32'h2011004f;
+20'd11: instruction <= 32'hae11000c;
+20'd12: instruction <= 32'h20110066;
+20'd13: instruction <= 32'hae110010;
+20'd14: instruction <= 32'h2011006d;
+20'd15: instruction <= 32'hae110014;
+20'd16: instruction <= 32'h2011007d;
+20'd17: instruction <= 32'hae110018;
+20'd18: instruction <= 32'h20110007;
+20'd19: instruction <= 32'hae11001c;
+20'd20: instruction <= 32'h2011007f;
+20'd21: instruction <= 32'hae110020;
+20'd22: instruction <= 32'h2011006f;
+20'd23: instruction <= 32'hae110024;
+20'd24: instruction <= 32'h20110077;
+20'd25: instruction <= 32'hae110028;
+20'd26: instruction <= 32'h2011007c;
+20'd27: instruction <= 32'hae11002c;
+20'd28: instruction <= 32'h20110058;
+20'd29: instruction <= 32'hae110030;
+20'd30: instruction <= 32'h2011005e;
+20'd31: instruction <= 32'hae110034;
+20'd32: instruction <= 32'h20110079;
+20'd33: instruction <= 32'hae110038;
+20'd34: instruction <= 32'h20110071;
+20'd35: instruction <= 32'hae11003c;
+20'd36: instruction <= 32'h3c114000;
+20'd37: instruction <= 32'h22310010;
+20'd38: instruction <= 32'h20100a80;
+20'd39: instruction <= 32'h22100001;
+20'd40: instruction <= 32'h22040000;
+20'd41: instruction <= 32'h22250000;
+20'd42: instruction <= 32'h0c00002c;
+20'd43: instruction <= 32'h08000027;
+20'd44: instruction <= 32'h23bdffe0;
+20'd45: instruction <= 32'hafbf0004;
+20'd46: instruction <= 32'hafb00008;
+20'd47: instruction <= 32'hafb1000c;
+20'd48: instruction <= 32'hafb20010;
+20'd49: instruction <= 32'hafb30014;
+20'd50: instruction <= 32'hafb40018;
+20'd51: instruction <= 32'hafb5001c;
+20'd52: instruction <= 32'hafb60020;
+20'd53: instruction <= 32'h20900000;
+20'd54: instruction <= 32'h20b10000;
+20'd55: instruction <= 32'h3c124000;
+20'd56: instruction <= 32'h22520020;
+20'd57: instruction <= 32'h20132ed4;
+20'd58: instruction <= 32'h22140000;
+20'd59: instruction <= 32'h20160100;
+20'd60: instruction <= 32'h20150004;
+20'd61: instruction <= 32'h3288000f;
+20'd62: instruction <= 32'h00084080;
+20'd63: instruction <= 32'h02484020;
+20'd64: instruction <= 32'h8d080000;
+20'd65: instruction <= 32'h01164025;
+20'd66: instruction <= 32'hae280000;
+20'd67: instruction <= 32'h0014a102;
+20'd68: instruction <= 32'h0016b040;
+20'd69: instruction <= 32'h200800ff;
+20'd70: instruction <= 32'h2108ffff;
+20'd71: instruction <= 32'h1d00fffe;
+20'd72: instruction <= 32'h22b5ffff;
+20'd73: instruction <= 32'h1ea0fff3;
+20'd74: instruction <= 32'h2273ffff;
+20'd75: instruction <= 32'h1e60ffee;
+20'd76: instruction <= 32'h8fbf0004;
+20'd77: instruction <= 32'h8fb00008;
+20'd78: instruction <= 32'h8fb1000c;
+20'd79: instruction <= 32'h8fb20010;
+20'd80: instruction <= 32'h8fb30014;
+20'd81: instruction <= 32'h8fb40018;
+20'd82: instruction <= 32'h8fb5001c;
+20'd83: instruction <= 32'h8fb60020;
+20'd84: instruction <= 32'h23bd0020;
+20'd85: instruction <= 32'h03e00008;
diff --git a/20display_num_mars.txt b/20display_num_mars.txt
new file mode 100644
index 0000000..1494ae8
--- /dev/null
+++ b/20display_num_mars.txt
@@ -0,0 +1,86 @@
+3c1d4000
+23bd07ff
+3c104000
+22100020
+2011003f
+ae110000
+20110006
+ae110004
+2011005b
+ae110008
+2011004f
+ae11000c
+20110066
+ae110010
+2011006d
+ae110014
+2011007d
+ae110018
+20110007
+ae11001c
+2011007f
+ae110020
+2011006f
+ae110024
+20110077
+ae110028
+2011007c
+ae11002c
+20110058
+ae110030
+2011005e
+ae110034
+20110079
+ae110038
+20110071
+ae11003c
+3c114000
+22310010
+20100a80
+22100001
+22040000
+22250000
+0c00002c
+08000027
+23bdffe0
+afbf0004
+afb00008
+afb1000c
+afb20010
+afb30014
+afb40018
+afb5001c
+afb60020
+20900000
+20b10000
+3c124000
+22520020
+20132ed4
+22140000
+20160100
+20150004
+3288000f
+00084080
+02484020
+8d080000
+01164025
+ae280000
+0014a102
+0016b040
+200800ff
+2108ffff
+1d00fffe
+22b5ffff
+1ea0fff3
+2273ffff
+1e60ffee
+8fbf0004
+8fb00008
+8fb1000c
+8fb20010
+8fb30014
+8fb40018
+8fb5001c
+8fb60020
+23bd0020
+03e00008