diff --git a/src/main.c b/src/main.c
index 0593a1c..fc40532 100644
--- a/src/main.c
+++ b/src/main.c
@@ -103,9 +103,9 @@ display_string(uint16_t attr, const char *str)
 }
 
 void
-debug_write_uint(unsigned v)
+debug_write_uint(uint32_t v)
 {
-	char buf[20], *p = buf + sizeof buf;
+	char buf[50], *p = buf + sizeof buf;
 	p--;
 	*p = 0;
 	do {
@@ -116,6 +116,20 @@ debug_write_uint(unsigned v)
 	debug_write(p);
 }
 
+void
+debug_write_hex(uint64_t v)
+{
+	char buf[50], *p = buf + sizeof buf;
+	p--;
+	*p = 0;
+	do {
+		p--;
+		*p = "0123456789ABCDEF"[v % 16];
+		v /= 16;
+	} while (v);
+	debug_write(p);
+}
+
 #define PG_PRESENT 0x001
 #define PG_WRITE   0x002
 #define PG_USER    0x004
@@ -189,6 +203,7 @@ extern struct exPXE *exPXE;
 #define PXENV_TFTP_OPEN  0x0020
 #define PXENV_TFTP_CLOSE 0x0021
 #define PXENV_TFTP_READ  0x0022
+#define PXENV_TFTP_READ_FILE  0x0023
 
 typedef struct __attribute__((packed)) s_PXENV_GET_CACHED {
 	uint16_t      status;
@@ -220,6 +235,20 @@ typedef struct __attribute__((packed)) s_PXENV_TFTP_CLOSE {
 	uint16_t      status;
 } t_PXENV_TFTP_CLOSE;
 
+typedef struct __attribute__((packed)) s_PXENV_TFTP_READ_FILE {
+	uint16_t      status;
+	uint8_t       filename[128];
+	uint32_t      buffer_size;
+	uint32_t      buffer_addr;
+	uint32_t      server_ip;
+	uint32_t      gateway_ip;
+	uint32_t      mcast_ip;
+	uint16_t      client_port;
+	uint16_t      server_port;
+	uint16_t      open_timeout;
+	uint16_t      reopen_delay;
+} t_PXENV_TFTP_READ_FILE;
+
 /**
  * return type for fs drivers
  */
@@ -305,6 +334,34 @@ get_cached()
 	debug_write("\r\n");
 }
 
+void
+receive_file()
+{
+	unsigned ret;
+
+	for (int i = 0; i < 512; i++) {
+		pxe_cmd_buf[i] = 0;
+	}
+	
+	t_PXENV_TFTP_READ_FILE *t_readf = (void *)pxe_cmd_buf;
+	t_readf->server_ip = pxe_sip;
+	t_readf->gateway_ip = pxe_gip;
+	t_readf->buffer_addr = 0x100000;
+	t_readf->buffer_size = 0x100000;
+	memcpy(t_readf->filename, "/initrd", 8);
+	t_readf->server_port = 69 << 8;
+
+	debug_write("Performing TFTP_READ_FILE\r\n");
+	ret = pxe_call(PXENV_TFTP_READ_FILE, (uint16_t)(uintptr_t)pxe_cmd_buf, 0x0000);
+
+	debug_write("ret=");
+	debug_write_uint(ret);
+	debug_write("  status=");
+	debug_write_uint(t_readf->status);
+	debug_write("\r\n");
+}
+
+#if 0
 void
 receive_file(void)
 {
@@ -370,6 +427,7 @@ receive_file(void)
 	debug_write_uint(t_open->status);
 	debug_write("\r\n");
 }
+#endif
 
 void
 main()
@@ -392,21 +450,26 @@ main()
 		pxe_entry = exPXE->rmentry;
 	}
 
-	/*
 	memcpy(bootboot.magic, BOOTBOOT_MAGIC, sizeof bootboot.magic);
 	bootboot.size = 128;
 	bootboot.protocol = PROTOCOL_MINIMAL | LOADER_BIOS;
 	bootboot.numcores = 1;
 
+	debug_write("BEGIN MEMMAP\r\n");
 	struct e820_entry *end = bios_getmap(memmap);
 	for (int i = 0; ; i++) {
 		if (&memmap[i] >= end) break;
-		char buf[2];
+		char buf[3];
 		buf[0] = memmap[i].type < 10 ? memmap[i].type + '0' : '?';
-		buf[1] = 0;
+		buf[1] = ' ';
+		buf[2] = 0;
 		debug_write(buf);
+		debug_write_hex(memmap[i].base);
+		debug_write(" ");
+		debug_write_uint(memmap[i].length);
+		debug_write("\r\n");
 	}
-	*/
+	debug_write("END MEMMAP\r\n");
 
 	//pg_setup();
 
diff --git a/src/nbp.S b/src/nbp.S
index da44577..2cc0d8a 100644
--- a/src/nbp.S
+++ b/src/nbp.S
@@ -52,6 +52,9 @@ _start:     cli
             xor         %ax, %ax
             mov         %ax, %es
 
+            mov         $isr_double_fault, 0x0020
+            mov         $0, 0x0020+2
+
 
             // a20_enable: Allow use of 'high' (>1Mb) memory
 a20_enable: // Of all the ways to toggle A20, we only try the Fast A20 Gate.
@@ -72,6 +75,31 @@ prot_enter: lgdt        GDT_PTR
             .code32
             jmp         main
 
+            .text
+            .code16
+
+isr_double_fault:
+            mov         $msg_double_fault, %edx
+
+.bwloop:    cmpb        $0, (%edx)
+            jz          .bwreturn
+
+            xor         %bx, %bx
+            mov         $0x0E, %ah
+            mov         (%edx), %al
+
+            push        %edx
+            int         $0x10
+            pop         %edx
+
+            add         $1, %edx
+            jmp         .bwloop
+
+.bwreturn:
+            
+1:          jmp         1b
+
+msg_double_fault: .asciz "double fault"
             .data
 
             .global     PXENV