diff --git a/Makefile b/Makefile
index 4fde358..705b090 100644
--- a/Makefile
+++ b/Makefile
@@ -35,7 +35,7 @@ polmon.elf: LDFLAGS += -T flat1000.ld
 polmon.elf: polmon.o stdlib.o
 
 polio.elf: LDFLAGS += -T flat0600.ld
-polio.elf: polio.s fat12.o
+polio.elf: polio-main.o polio.s fat12.o paracomm.o
 
 wozmon.o: polmon.cc
 wozmon.o: CPPFLAGS = -DWOZMON=1
diff --git a/polio-main.c b/polio-main.c
new file mode 100644
index 0000000..0adb3f3
--- /dev/null
+++ b/polio-main.c
@@ -0,0 +1,101 @@
+#include <stdint.h>
+
+#include "fat12.h"
+#include "paracomm.h"
+
+#define kFatAddr ((void*)0x1a00)
+#define kRootDirAddr ((void*)0x1c00)
+#define kPolmonAddr ((void*)0x1000)
+#define kInt80Vector ((uint16_t*)(0x80 * 4))
+#define kParallelDataPort 0x3bc
+#define kParallelStatusPort 0x3bd
+#define kParallelControlPort 0x3be
+#define kParaDelay 400
+
+void dosdbt();
+void int80h();
+
+uint8_t* parabuf;
+uint8_t parasize;
+
+static void paracb(const uint8_t* buf, uint8_t size) {
+    if (size > parasize) {
+        return paracb(buf, parasize);
+    }
+    for (int i = 0; i < size; i++) {
+        parabuf[i] = buf[i];
+    }
+    parasize = 0;
+}
+
+static void die() {
+    while (1) {
+    }
+}
+
+static void __outb__(uint16_t port, uint8_t data) {
+    register uint16_t p asm("dx") = port;
+    register uint8_t d asm("al") = data;
+    asm volatile("outb %0, %1" ::"r"(d), "r"(p));
+}
+
+static uint8_t __inb__(uint16_t port) {
+    register uint16_t p asm("dx") = port;
+    register uint8_t d asm("al");
+    asm volatile("inb %1, %0" : "=r"(d) : "r"(p));
+    return d;
+}
+
+static void __delay__(int n) {
+    for (int i = 0; i < n; i++) {
+        asm volatile("");
+    }
+}
+
+static void paraxfer() {
+    uint8_t mosib = paracomm_nextbyte();
+    __outb__(kParallelDataPort, mosib);
+    __outb__(kParallelControlPort, 1);
+    __delay__(kParaDelay);
+    __outb__(kParallelControlPort, 0);
+    __delay__(kParaDelay);
+    uint8_t mison = __inb__(kParallelStatusPort) >> 4;
+    paracomm_feed(mison);
+}
+
+void pararecv(uint8_t* addr, uint8_t size) {
+    parabuf = addr;
+    parasize = size;
+    for (int i = 0; i < 1 + 2 + size * 2; i++) {
+        if (!parasize) {
+            break;
+        }
+        paraxfer();
+    }
+}
+
+void parasend(uint8_t* addr, uint8_t size) {
+    for (int i = 0; i < size; i++) {
+        paracomm_send(addr[i]);
+    }
+    for (int i = 0; i < size + 2; i++) {
+        paraxfer();
+    }
+}
+
+int main() {
+    dosdbt();
+    paracomm_init(paracb);
+
+    fat12_init(kFatAddr, kRootDirAddr);
+
+    uint16_t* int80v = kInt80Vector;
+    int80v[0] = (uint16_t)int80h;
+    int80v[1] = 0;
+
+    if (fat12_readfile("POLMON  COM", kPolmonAddr)) {
+        die();
+    }
+
+    asm volatile("jmp *%0" ::"r"(kPolmonAddr));
+}
diff --git a/polio.s b/polio.s
index 95e4045..5db7ffb 100644
--- a/polio.s
+++ b/polio.s
@@ -5,6 +5,10 @@
     .section .init
     .global _start
 _start:
+    cli
+    mov ax, 0x2000      # stack address
+    mov sp, ax          # ss should already be 0
+    sti
     jmp main
 
 
@@ -12,7 +16,7 @@ diskpointer = 0x1e*4
 dbtbase = 0x0500
 
     .section .text.dosdbt
-    .local dosdbt
+    .global dosdbt
 dosdbt:                    # assumes es=0
     push si
     push di
@@ -103,51 +107,27 @@ formattrack:
     int 0x13
     ret
 
-
 readfile:
     mov ax, [bp+0]
     mov dx, [bp+2]
     call fat12_readfile
     ret
 
+sendpara:
+    mov ax, [bp+0]
+    mov dx, [bp+2]
+    call parasend
+    ret
 
-    .section .rodata.polmon_str
-polmon_str: .ascii "POLMON  COM"
-polmon_addr = 0x1000
-
-    .section .text.main
-    .global main
-main:
-    cli
-    mov ax, 0x2000      # stack address
-    mov sp, ax          # ss should already be 0
-    sti
-    call dosdbt
-    mov ax, 0x1a00      # first sector of first fat
-    mov dx, 0x1c00      # first sector of root dir
-    call fat12_init
-
-    mov si, 0x80*4
-    movw [si], offset int80h
-    movw [si+2], 0
-
-    mov ax, offset polmon_str 
-    mov dx, polmon_addr
-    call fat12_readfile
-    test ax, ax
-    jnz 0f
-
-    jmp polmon_addr
-0:
-    mov ax, 0x0e42
-    mov bh, 0
-    int 0x10
-    cli
-    hlt
+recvpara:
+    mov ax, [bp+0]
+    mov dx, [bp+2]
+    call pararecv
+    ret
 
     .section .text.int80h
+    .global int80h
 int80h:
-    push bx
     push si
     push di
     push bp
@@ -163,7 +143,7 @@ int80h:
     xor ah, ah
     mov si, ax
     mov bp, sp
-    lea bp, [bp + 18]       # 12 for us, 6 for the interrupt
+    lea bp, [bp + 16]       # 10 for us, 6 for the interrupt
     call [int80h_table+si]
     jmp 1f
 0:
@@ -174,10 +154,8 @@ int80h:
     pop bp
     pop di
     pop si
-    pop bx
     iret
 
-
     .section .rodata.int80h
 int80h_table:
     .word offset copy           # 0x00
@@ -185,5 +163,7 @@ int80h_table:
     .word offset writesector    # 0x02
     .word offset formattrack    # 0x03
     .word offset readfile       # 0x04
+    .word offset recvpara       # 0x05
+    .word offset sendpara       # 0x06
 
 int80h_entries = . - int80h_table