diff --git a/.gitignore b/.gitignore
index 16e44d5..fe93128 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,4 +1,4 @@
 *.tap
 *bin
 *bincs
-ac
+ttttt
diff --git a/Makefile b/Makefile
index df5d24d..d255a68 100644
--- a/Makefile
+++ b/Makefile
@@ -1,33 +1,28 @@
-program.tap: program.asm headerbincs body.tap
-	pasmo program.asm program.tap
+program.tap: header.block body.block
+	cat header.block body.block > program.tap
 
-headerbincs: headerbin ac
-	cp headerbin headerbincs
-	./ac headerbincs
+header.block: header ttttt
+	./ttttt header
 
-headerbin: header.tap
-	dd if=header.tap of=headerbin bs=1 count=18
+header: header.asm body.block
+	pasmo header.asm headerlong
+	dd if=headerlong of=header bs=18 count=1
+	rm -f headerlong
 
-header.tap: header.asm body.tap
-	pasmo header.asm header.tap
+body.block: body ttttt
+	./ttttt body
 
-body.tap: body.asm bodybincs
-	pasmo body.asm body.tap
+body: remload.asm code.asm
+	pasmo remload.asm body
 
-bodybincs: bodybin ac
-	cp bodybin bodybincs
-	./ac bodybincs
-
-bodybin: remload.asm code.asm
-	pasmo remload.asm bodybin
-
-ac: append_checksum.c
-	cc append_checksum.c -o ac
+ttttt: ttttt.c
+	cc ttttt.c -o ttttt
 
 clean:
 	rm -f *.tap
-	rm -f *bin
-	rm -f *bincs
-	rm -f ac
+	rm -f *.block
+	rm -f body
+	rm -f header
+	rm -f ttttt
 
 .PHONY: clean
diff --git a/append_checksum.c b/append_checksum.c
deleted file mode 100644
index fb1f309..0000000
--- a/append_checksum.c
+++ /dev/null
@@ -1,26 +0,0 @@
-#include <fcntl.h>
-#include <unistd.h>
-#include <stdio.h>
-
-int main(int argc, char *argv[])
-{
-	int fd;
-	unsigned char tally = 0;
-	unsigned char next = 0;
-	if (argc!=2) return -1;
-
-	fd = open(argv[1], O_RDWR|O_APPEND);
-	if (fd<0) return -2;
-
-	while (read(fd, &next, 1)) {
-		//printf("Tally: %X, next byte: %X\n", tally, next);
-		tally ^= next;
-	};
-
-	printf("Final tally: %X\n", tally);
-
-	write(fd, &tally, 1);
-
-	close(fd);
-	return 0;
-}
diff --git a/body.asm b/body.asm
deleted file mode 100644
index 3796e6e..0000000
--- a/body.asm
+++ /dev/null
@@ -1,7 +0,0 @@
-bodylength:
-	dw bodyend - bodycontent
-
-bodycontent:
-INCBIN bodybincs
-
-bodyend:
diff --git a/header.asm b/header.asm
index 7c0758a..6d13bfa 100644
--- a/header.asm
+++ b/header.asm
@@ -20,5 +20,5 @@ checksum:
 	db 0
 
 bodytap:
-INCBIN body.tap
+INCBIN body.block
 endbodytap:
diff --git a/program.asm b/program.asm
deleted file mode 100644
index cebb655..0000000
--- a/program.asm
+++ /dev/null
@@ -1,5 +0,0 @@
-headlength:
-	dw 19
-
-INCBIN headerbincs
-INCBIN body.tap
diff --git a/ttttt.c b/ttttt.c
new file mode 100644
index 0000000..60c81cc
--- /dev/null
+++ b/ttttt.c
@@ -0,0 +1,69 @@
+/* McPhail's Tip-Top TAP Top-Tailer
+ * Takes a raw code file as input
+ * Prepends data length and appends xor checksum
+ * Outputs to new file with .block suffix */
+
+
+#include <fcntl.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <linux/limits.h>
+#include <string.h>
+
+int main(int argc, char *argv[])
+{
+	int fdin, fdout;
+	char outfilename[PATH_MAX];
+	unsigned int count = 0;
+	unsigned char tally = 0;
+	unsigned char next = 0;
+	if (argc!=2) {
+		printf("Please specify file to read.\n");
+		return -1;
+	}
+
+	fdin = open(argv[1], O_RDONLY);
+	if (fdin<0) {
+		printf("Couldn't open %s. for reading\n", argv[1]);
+		return -1;
+	}
+
+	snprintf(outfilename, PATH_MAX, "%s.block", argv[1]);
+	outfilename[PATH_MAX - 1] = '\0';
+	if (! strcmp(argv[1], outfilename)) {
+		printf("Filename too long - would clobber existing.\n");
+		close(fdin);
+		return -1;
+	}
+
+	fdout = open(outfilename, O_CREAT|O_WRONLY|O_TRUNC, S_IRUSR|S_IWUSR|S_IRGRP|S_IWGRP|S_IROTH);
+	if (fdout<0) {
+		printf("Couldn't open %s for writing.\n", outfilename);
+		close(fdin);
+		return -1;
+	}
+
+	while (read(fdin, &next, 1)) {
+		tally ^= next;
+		count ++;
+	};
+	lseek(fdin, 0, SEEK_SET);
+
+	char lsb = (count+1)&255;
+	char msb = ((count+1)>>8)&255;
+	write(fdout, &lsb, 1);
+	write(fdout, &msb, 1);
+	while (read(fdin, &next, 1)) {
+		write(fdout, &next, 1);
+	}
+	write(fdout, &tally, 1);
+
+	close(fdout);
+	close(fdin);
+
+	printf("File %s written.\n", outfilename);
+	printf("Code length including first byte is %d (0x%.4X).\n", count, count);
+	printf("Removing first byte gives 0x%.4X.\n", count-1);
+
+	return 0;
+}