diff --git a/XTMax/Code/XTMax/XTMax.ino b/XTMax/Code/XTMax/XTMax.ino
index 2bb8b56..2ac3958 100644
--- a/XTMax/Code/XTMax/XTMax.ino
+++ b/XTMax/Code/XTMax/XTMax.ino
@@ -37,15 +37,11 @@
 //
 // Revision 7 01/12/2025
 // - Refactor SD card I/O
-// - Add support for 16-bit EMS page offsets
+// - Add support for 16-bit EMS page offsets.
 //
 // Revision 8 01/20/2025
 // - Added chip select for a second PSRAM to allow access to 16 MB of Expanded RAM
 //
-// Revision 9 01/26/2024
-// - Add support for BIOS ROM extension (Boot ROM)
-// - Add scrach registers for Boot ROM hooking
-//
 //------------------------------------------------------------------------
 //
 // Copyright (c) 2024 Ted Fried
@@ -75,8 +71,6 @@
 #include <stdint.h>
 #include <stdio.h>
 
-#include "bootrom.h"
-
 
 // Teensy 4.1 pin assignments
 //
@@ -172,7 +166,7 @@
 
 #define EMS_TOTAL_SIZE     (16*1024*1024)
 
-#define SD_BASE            0x280  // Must be a multiple of 8.
+#define SD_BASE            0x280  // Must be a multiple of 2.
 
     
 // --------------------------------------------------------------------------------------------------
@@ -197,7 +191,6 @@ uint8_t   spi_shift_out =0;
 uint8_t   sd_spi_datain =0;
 uint32_t  sd_spi_cs_n = 0x0;
 uint32_t  sd_spi_dataout =0;
-uint8_t   sd_scratch_register[5] = {0, 0, 0, 0, 0};
 
 uint8_t XTMax_MEM_Response_Array[16];
 
@@ -580,16 +573,6 @@ inline void Mem_Read_Cycle() {
      
       GPIO8_DR = sd_pin_outputs + MUX_DATA_n_HIGH + CHRDY_OE_n_HIGH + DATA_OE_n_HIGH;
     }
-    else if (isa_address>=BOOTROM_ADDR && isa_address<BOOTROM_ADDR+sizeof(BOOTROM)) {   // Boot ROM
-      isa_data_out = BOOTROM[isa_address-BOOTROM_ADDR];
-      GPIO7_DR = GPIO7_DATA_OUT_UNSCRAMBLE + MUX_ADDR_n_LOW  + CHRDY_OUT_LOW + trigger_out;
-      GPIO8_DR = sd_pin_outputs + MUX_DATA_n_HIGH + CHRDY_OE_n_HIGH + DATA_OE_n_LOW;
-
-      while ( (gpio9_int&0xF0) != 0xF0 ) { gpio9_int = GPIO9_DR; }  // Wait here until cycle is complete
-
-      GPIO8_DR = sd_pin_outputs + MUX_DATA_n_HIGH + CHRDY_OE_n_HIGH + DATA_OE_n_HIGH;
-    }
-
     return;
 }
 
@@ -629,6 +612,7 @@ inline void Mem_Write_Cycle() {
       GPIO7_DR = GPIO7_DATA_OUT_UNSCRAMBLE + MUX_ADDR_n_LOW  + CHRDY_OUT_LOW + trigger_out;
       GPIO8_DR = sd_pin_outputs + MUX_DATA_n_HIGH + CHRDY_OE_n_HIGH + DATA_OE_n_HIGH;
     }   
+
     else if (isa_address<0xA0000)   {    // XTMax stores the full 640 KB conventional memory
       GPIO7_DR = GPIO7_DATA_OUT_UNSCRAMBLE + MUX_ADDR_n_HIGH  + CHRDY_OUT_LOW + trigger_out;
       GPIO8_DR = sd_pin_outputs + MUX_DATA_n_LOW + CHRDY_OE_n_HIGH + DATA_OE_n_HIGH;
@@ -676,18 +660,12 @@ inline void IO_Read_Cycle() {
     }
    
        
-    else if ((isa_address&0x0FF8)==SD_BASE )  {   // Location of SD Card registers
+    else if ((isa_address&0x0FFE)==SD_BASE )  {   // Location of SD Card registers
  
-      switch (isa_address)  {
-        case SD_BASE:     // First two registers serve the same function (to allow use of Word I/O)
-        case SD_BASE+1:   sd_spi_dataout = 0xff; SD_SPI_Cycle(); isa_data_out = sd_spi_datain; break;
-        case SD_BASE+2:   break; // Write only
-        case SD_BASE+3:   isa_data_out = sd_scratch_register[0]; break;
-        case SD_BASE+4:   isa_data_out = sd_scratch_register[1]; break;
-        case SD_BASE+5:   isa_data_out = sd_scratch_register[2]; break;
-        case SD_BASE+6:   isa_data_out = sd_scratch_register[3]; break;
-        case SD_BASE+7:   isa_data_out = sd_scratch_register[4]; break;
-        }
+      // Both registers serve the same function (to allow use of Word I/O)
+      sd_spi_dataout = 0xff;
+      SD_SPI_Cycle();
+      isa_data_out = sd_spi_datain;
      
       GPIO7_DR = GPIO7_DATA_OUT_UNSCRAMBLE + MUX_ADDR_n_LOW  + CHRDY_OUT_LOW + trigger_out;
       GPIO8_DR = sd_pin_outputs + MUX_DATA_n_HIGH + CHRDY_OE_n_HIGH + DATA_OE_n_LOW;
@@ -735,7 +713,7 @@ inline void IO_Write_Cycle() {
     }
    
    
-    else if ((isa_address&0x0FF8)==SD_BASE )  {   // Location of SD Card registers
+    else if ((isa_address&0x0FFC)==SD_BASE )  {   // Location of SD Card registers
       GPIO7_DR = GPIO7_DATA_OUT_UNSCRAMBLE + MUX_ADDR_n_HIGH  + CHRDY_OUT_LOW + trigger_out;
       GPIO8_DR = sd_pin_outputs + MUX_DATA_n_LOW + CHRDY_OE_n_HIGH + DATA_OE_n_HIGH;
    
@@ -747,11 +725,6 @@ inline void IO_Write_Cycle() {
         case SD_BASE:     // First two registers serve the same function (to allow use of Word I/O)
         case SD_BASE+1:   sd_spi_dataout = data_in;  SD_SPI_Cycle(); break;
         case SD_BASE+2:   sd_spi_cs_n    = data_in&0x1;              break;
-        case SD_BASE+3:   sd_scratch_register[0] = data_in; break;
-        case SD_BASE+4:   sd_scratch_register[1] = data_in; break;
-        case SD_BASE+5:   sd_scratch_register[2] = data_in; break;
-        case SD_BASE+6:   sd_scratch_register[3] = data_in; break;
-        case SD_BASE+7:   sd_scratch_register[4] = data_in; break;
       }
      
       //gpio9_int = GPIO9_DR;
diff --git a/XTMax/Code/XTMax/bootrom.h b/XTMax/Code/XTMax/bootrom.h
deleted file mode 100644
index b32e164..0000000
--- a/XTMax/Code/XTMax/bootrom.h
+++ /dev/null
@@ -1,130 +0,0 @@
-#define BOOTROM_ADDR 0xCE000
-unsigned char BOOTROM[] = {
-    85, 170, 4, 6, 80, 82, 250, 184, 19, 229, 232, 129, 4, 232, 137, 3,
-    115, 3, 233, 188, 0, 84, 88, 57, 224, 116, 39, 62, 161, 255, 255, 62,
-    199, 6, 255, 255, 170, 170, 62, 128, 62, 0, 0, 170, 62, 163, 255, 255,
-    116, 2, 235, 14, 80, 48, 192, 176, 64, 246, 224, 88, 116, 4, 48, 210,
-    235, 8, 178, 1, 184, 85, 229, 232, 68, 4, 184, 131, 2, 146, 238, 184,
-    122, 229, 232, 57, 4, 49, 192, 142, 192, 38, 161, 78, 0, 186, 132, 2,
-    239, 232, 72, 4, 184, 37, 230, 232, 36, 4, 38, 161, 76, 0, 186, 134,
-    2, 239, 232, 55, 4, 184, 41, 230, 232, 19, 4, 184, 143, 229, 232, 13,
-    4, 184, 0, 192, 38, 163, 78, 0, 232, 33, 4, 184, 37, 230, 232, 253,
-    3, 184, 214, 224, 38, 163, 76, 0, 232, 17, 4, 184, 41, 230, 232, 237,
-    3, 184, 164, 229, 232, 231, 3, 184, 0, 192, 38, 163, 6, 1, 232, 251,
-    3, 184, 37, 230, 232, 215, 3, 184, 138, 225, 38, 163, 4, 1, 232, 235,
-    3, 184, 41, 230, 232, 199, 3, 184, 64, 0, 142, 192, 38, 254, 6, 117,
-    0, 251, 90, 88, 7, 203, 85, 86, 128, 250, 128, 116, 26, 137, 197, 137,
-    214, 156, 14, 184, 49, 225, 80, 156, 186, 132, 2, 237, 80, 186, 134, 2,
-    237, 80, 137, 232, 137, 242, 207, 128, 252, 21, 126, 5, 232, 113, 0, 235,
-    34, 128, 252, 1, 116, 10, 128, 252, 21, 116, 5, 190, 35, 225, 235, 3,
-    190, 49, 225, 86, 137, 222, 136, 227, 48, 255, 208, 227, 135, 222, 46, 255,
-    164, 68, 225, 140, 197, 190, 64, 0, 142, 198, 38, 136, 38, 116, 0, 142,
-    197, 137, 229, 139, 118, 8, 86, 115, 4, 157, 249, 235, 2, 157, 248, 94,
-    93, 202, 2, 0, 45, 227, 154, 225, 174, 225, 63, 226, 238, 226, 112, 225,
-    112, 225, 112, 225, 9, 227, 45, 227, 112, 225, 112, 225, 31, 227, 45, 227,
-    112, 225, 112, 225, 45, 227, 45, 227, 112, 225, 112, 225, 45, 227, 47, 227,
-    80, 184, 8, 230, 232, 23, 3, 88, 80, 136, 224, 48, 228, 232, 44, 3,
-    184, 41, 230, 232, 8, 3, 88, 233, 178, 1, 0, 4, 255, 0, 0, 255,
-    255, 0, 200, 0, 0, 0, 0, 0, 63, 0, 6, 189, 64, 0, 142, 197,
-    48, 228, 38, 134, 38, 116, 0, 132, 228, 116, 1, 249, 7, 195, 132, 192,
-    117, 3, 233, 135, 1, 80, 48, 228, 137, 198, 83, 232, 138, 1, 137, 197,
-    1, 240, 137, 222, 131, 211, 0, 232, 177, 1, 91, 88, 115, 3, 233, 111,
-    1, 83, 81, 82, 87, 80, 137, 193, 48, 237, 137, 223, 186, 130, 2, 176,
-    0, 238, 81, 137, 232, 137, 243, 177, 81, 232, 113, 2, 114, 64, 186, 128,
-    2, 185, 80, 195, 235, 3, 232, 135, 2, 236, 60, 254, 224, 248, 117, 46,
-    185, 0, 1, 82, 186, 131, 2, 236, 90, 132, 192, 252, 116, 4, 243, 109,
-    235, 4, 237, 171, 226, 252, 237, 131, 197, 1, 131, 214, 0, 89, 226, 194,
-    186, 130, 2, 176, 1, 238, 88, 95, 90, 89, 91, 233, 22, 1, 186, 130,
-    2, 176, 1, 238, 89, 88, 40, 200, 95, 90, 89, 91, 233, 249, 0, 132,
-    192, 117, 3, 233, 246, 0, 80, 48, 228, 137, 198, 83, 232, 249, 0, 137,
-    197, 1, 240, 137, 222, 131, 211, 0, 232, 32, 1, 91, 88, 115, 3, 233,
-    222, 0, 30, 83, 81, 82, 87, 80, 137, 193, 48, 237, 137, 223, 140, 192,
-    142, 216, 186, 130, 2, 176, 0, 238, 81, 137, 232, 137, 243, 177, 88, 232,
-    219, 1, 114, 89, 186, 128, 2, 176, 254, 238, 185, 0, 1, 135, 247, 82,
-    186, 131, 2, 236, 90, 132, 192, 252, 116, 4, 243, 111, 235, 4, 173, 239,
-    226, 252, 135, 254, 185, 80, 195, 235, 3, 232, 212, 1, 236, 60, 255, 225,
-    248, 36, 31, 60, 5, 117, 38, 185, 80, 195, 235, 3, 232, 193, 1, 236,
-    132, 192, 225, 248, 116, 23, 131, 197, 1, 131, 214, 0, 89, 226, 169, 186,
-    130, 2, 176, 1, 238, 88, 95, 90, 89, 91, 31, 235, 103, 186, 130, 2,
-    176, 1, 238, 89, 88, 40, 200, 95, 90, 89, 91, 31, 235, 74, 132, 192,
-    116, 74, 80, 48, 228, 137, 197, 83, 232, 77, 0, 1, 232, 131, 211, 0,
-    232, 120, 0, 91, 88, 114, 57, 235, 59, 182, 254, 6, 184, 64, 0, 142,
-    192, 38, 138, 22, 117, 0, 7, 181, 254, 177, 255, 49, 192, 248, 195, 80,
-    83, 232, 36, 0, 232, 84, 0, 91, 88, 114, 21, 235, 23, 235, 21, 180,
-    3, 232, 94, 0, 135, 209, 248, 195, 180, 170, 249, 195, 180, 1, 249, 195,
-    180, 4, 249, 195, 48, 228, 248, 195, 49, 192, 49, 219, 82, 81, 82, 136,
-    200, 36, 192, 209, 224, 209, 224, 136, 232, 185, 255, 0, 247, 225, 90, 136,
-    241, 48, 237, 1, 200, 177, 63, 247, 225, 89, 81, 48, 237, 128, 225, 63,
-    73, 1, 200, 131, 210, 0, 137, 211, 89, 90, 195, 81, 82, 232, 18, 0,
-    57, 211, 114, 10, 119, 4, 57, 200, 114, 4, 249, 90, 89, 195, 248, 90,
-    89, 195, 186, 250, 0, 185, 63, 197, 195, 80, 30, 83, 81, 82, 86, 184,
-    0, 192, 142, 216, 186, 130, 2, 176, 1, 238, 49, 201, 186, 232, 3, 180,
-    134, 205, 21, 186, 128, 2, 176, 255, 185, 80, 0, 238, 226, 253, 186, 130,
-    2, 176, 0, 238, 190, 69, 228, 185, 1, 0, 180, 1, 232, 79, 0, 114,
-    54, 190, 75, 228, 185, 5, 0, 180, 1, 232, 66, 0, 114, 41, 187, 100,
-    0, 190, 81, 228, 185, 1, 0, 180, 1, 232, 50, 0, 190, 87, 228, 185,
-    1, 0, 180, 0, 232, 39, 0, 115, 14, 156, 49, 201, 186, 232, 3, 180,
-    134, 205, 21, 157, 75, 117, 218, 94, 90, 89, 91, 31, 114, 8, 184, 198,
-    229, 232, 122, 0, 88, 195, 184, 233, 229, 232, 114, 0, 88, 195, 186, 128,
-    2, 176, 255, 238, 81, 185, 6, 0, 252, 172, 238, 226, 252, 185, 8, 0,
-    236, 60, 255, 225, 251, 89, 56, 224, 118, 3, 249, 235, 4, 248, 236, 226,
-    253, 176, 255, 238, 195, 64, 0, 0, 0, 0, 149, 72, 0, 0, 1, 170,
-    135, 119, 0, 0, 0, 0, 1, 105, 64, 0, 0, 0, 1, 186, 128, 2,
-    80, 176, 255, 238, 136, 200, 136, 252, 239, 88, 134, 216, 239, 134, 216, 180,
-    1, 239, 185, 8, 0, 236, 60, 255, 225, 251, 132, 192, 116, 1, 249, 195,
-    81, 82, 49, 201, 186, 1, 0, 180, 134, 205, 21, 90, 89, 195, 156, 30,
-    83, 86, 137, 198, 184, 0, 192, 142, 216, 180, 14, 49, 219, 252, 172, 8,
-    192, 116, 4, 205, 16, 235, 247, 94, 91, 31, 157, 195, 156, 30, 83, 81,
-    82, 86, 137, 194, 184, 0, 192, 142, 216, 49, 219, 252, 137, 214, 177, 12,
-    211, 238, 131, 230, 15, 138, 132, 3, 229, 180, 14, 205, 16, 137, 214, 177,
-    8, 211, 238, 131, 230, 15, 138, 132, 3, 229, 180, 14, 205, 16, 137, 214,
-    177, 4, 211, 238, 131, 230, 15, 138, 132, 3, 229, 180, 14, 205, 16, 137,
-    214, 131, 230, 15, 138, 132, 3, 229, 180, 14, 205, 16, 94, 90, 89, 91,
-    31, 157, 195, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 65, 66, 67,
-    68, 69, 70, 66, 111, 111, 116, 82, 79, 77, 32, 102, 111, 114, 32, 88,
-    84, 77, 97, 120, 32, 118, 49, 46, 48, 13, 10, 67, 111, 112, 121, 114,
-    105, 103, 104, 116, 32, 40, 99, 41, 32, 50, 48, 50, 53, 32, 77, 97,
-    116, 116, 104, 105, 101, 117, 32, 66, 117, 99, 99, 104, 105, 97, 110, 101,
-    114, 105, 13, 10, 0, 67, 80, 85, 32, 115, 117, 112, 112, 111, 114, 116,
-    115, 32, 73, 78, 83, 47, 79, 85, 84, 83, 32, 105, 110, 115, 116, 114,
-    117, 99, 116, 105, 111, 110, 115, 13, 10, 0, 79, 108, 100, 32, 73, 78,
-    84, 49, 51, 104, 32, 86, 101, 99, 116, 111, 114, 32, 61, 32, 0, 78,
-    101, 119, 32, 73, 78, 84, 49, 51, 104, 32, 86, 101, 99, 116, 111, 114,
-    32, 61, 32, 0, 78, 101, 119, 32, 70, 105, 120, 101, 100, 32, 68, 105,
-    115, 107, 32, 80, 97, 114, 97, 109, 101, 116, 101, 114, 32, 84, 97, 98,
-    108, 101, 32, 61, 32, 0, 83, 68, 32, 67, 97, 114, 100, 32, 105, 110,
-    105, 116, 105, 97, 108, 105, 122, 101, 100, 32, 115, 117, 99, 99, 101, 115,
-    115, 102, 117, 108, 108, 121, 13, 10, 0, 83, 68, 32, 67, 97, 114, 100,
-    32, 102, 97, 105, 108, 101, 100, 32, 116, 111, 32, 105, 110, 105, 116, 105,
-    97, 108, 105, 122, 101, 13, 10, 0, 85, 110, 115, 117, 112, 112, 111, 114,
-    116, 101, 100, 32, 73, 78, 84, 49, 51, 104, 32, 70, 117, 110, 99, 116,
-    105, 111, 110, 32, 0, 58, 0, 32, 0, 13, 10, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 164};
\ No newline at end of file