diff --git a/Makefile b/Makefile
index 2bb0999..1dcf012 100644
--- a/Makefile
+++ b/Makefile
@@ -2,7 +2,7 @@ t ?= esp32
 
 TERMINAL_SPEED := 115200
 CPPFLAGS = -Wall -DDEBUGGING -DCPU_DEBUG=false -DTERMINAL_SPEED=$(TERMINAL_SPEED) -DUSE_OWN_KBD
-LIBRARIES = PS2KeyAdvanced PS2KeyMap
+LIBRARIES = PS2KeyAdvanced PS2KeyMap SimpleTimer
 
 ifeq ($t, esp8266)
 BOARD := d1_mini
@@ -11,7 +11,7 @@ EESZ := 4M1M
 F_CPU := 80
 CPPFLAGS += -DUSER_SETUP_LOADED -DILI9341_DRIVER -DTFT_CS=PIN_D8 -DTFT_DC=PIN_D1 \
 	-DTFT_RST=-1 -DSPI_FREQUENCY=40000000 -DLOAD_GLCD \
-	-DHARDWARE_H=\"hw/esp8bit.h\" -DPS2_SERIAL_KBD=\"UK\"
+	-DHARDWARE_H=\"hw/esp8bit.h\"
 LIBRARIES += TFT_eSPI SpiRAM LittleFS
 endif
 
diff --git a/io.cpp b/io.cpp
index 95e81aa..2671562 100644
--- a/io.cpp
+++ b/io.cpp
@@ -6,23 +6,24 @@
 #include <serial_kbd.h>
 #include <serial_dsp.h>
 #include <pia.h>
-#include <timed.h>
+#include <hardware.h>
 
 #include "io.h"
 #include "disp.h"
-#include "hardware.h"
 #include "config.h"
 
 void io::reset() {
+	_loading = false;
 	_dsp.reset();
 	_kbd.reset();
-
-	_loading = false;
-	PIA::reset();
+	_pia.reset();
+	_ch = 0;
 }
 
 bool io::start() {
-
+	hardware_interval_timer(10, [this]() { poll(); });
+	_pia.register_portb_write_handler([this](uint8_t b) { _dsp.write(b & 0x7f); });
+	_pia.register_porta_read_handler([this]() { uint8_t c = _ch; _ch = 0; return c; });
 	return files.start();
 }
 
@@ -34,18 +35,15 @@ void io::load() {
 }
 
 void io::enter(uint8_t key) {
-	PIA::write_ca1(false);
-	PIA::write_porta_in(key + 0x80);
-	PIA::write_ca1(true);
+	_pia.write_ca1(false);
+	_ch = key | 0x80;
+	_pia.write_ca1(true);
 }
 
-void io::write_portb(uint8_t b) {
-	b &= 0x7f;
-	_dsp.write(b);
-	PIA::write_portb(b);
-}
+void io::poll() {
+	if (_ch)
+		return;
 
-uint8_t io::read_cra() {
 	if (_loading) {
 		if (files.more())
 			enter(files.read());
@@ -56,16 +54,14 @@ uint8_t io::read_cra() {
 		if (c != -1)
 			enter(c);
 	}
-
-	return PIA::read_cra();
 }
 
 void io::checkpoint(Stream &s) {
-	PIA::checkpoint(s);
+	_pia.checkpoint(s);
 	_dsp.checkpoint(s);
 }
 
 void io::restore(Stream &s) {
-	PIA::restore(s);
+	_pia.restore(s);
 	_dsp.restore(s);
 }
diff --git a/io.h b/io.h
index 3b82852..58a7006 100644
--- a/io.h
+++ b/io.h
@@ -1,10 +1,9 @@
-#ifndef _IO_H
-#define _IO_H
+#pragma once
 
 class serial_kbd;
 class disp;
 
-class io: public Memory::Device, public PIA {
+class io: public Memory::Device {
 public:
 	io(filer &files, serial_kbd &kbd, disp &dsp): 
 		Memory::Device(Memory::page_size), files(files), _kbd(kbd), _dsp(dsp) {}
@@ -12,24 +11,22 @@ public:
 	void reset();
 	bool start();
 
-	void operator=(uint8_t b) { PIA::write(_acc, b); }
-	operator uint8_t() { return PIA::read(_acc); }
+	void operator=(uint8_t b) { _pia.write(_acc, b); }
+	operator uint8_t() { return _pia.read(_acc); }
 
 	void checkpoint(Stream &);
 	void restore(Stream &);
 
-	void write_portb(uint8_t);
-	uint8_t read_cra();
-
+	void poll();
 	void load();
 	filer &files;
 
 private:
+	PIA _pia;
 	serial_kbd &_kbd;
 	disp &_dsp;
 
 	void enter(uint8_t);
 	bool _loading;
+	uint8_t _ch;
 };
-
-#endif
diff --git a/screen_disp.cpp b/screen_disp.cpp
index 1dc9d0d..e60d51f 100644
--- a/screen_disp.cpp
+++ b/screen_disp.cpp
@@ -2,29 +2,23 @@
 #include <memory.h>
 #include <display.h>
 #include <serial_dsp.h>
-#include <timed.h>
 #include <hardware.h>
 
 #include "disp.h"
 #include "screen_disp.h"
 #include "config.h"
 
-static screen_disp *i;
-
-const int TICK_FREQ = 2;
-
-void IRAM_ATTR screen_disp::on_tick() {
-
-	static int tick = 0;
-	tick = (tick + 1) % 3;
-	i->cursor(tick < 2);
-}
-
 void screen_disp::reset() {
 
-	if (!i) {
-		i = this;
-		timer_create(TICK_FREQ, on_tick);
+	static bool first_time = true;
+
+	if (first_time) {
+		hardware_interval_timer(500, [this]() {
+			static int tick = 0;
+			tick = (tick + 1) % 3;
+			cursor(tick < 2);
+		});
+		first_time = false;
 	}
 
 	Display::begin(BG_COLOUR, FG_COLOUR, ORIENT);
diff --git a/screen_disp.h b/screen_disp.h
index 2a5181a..787552e 100644
--- a/screen_disp.h
+++ b/screen_disp.h
@@ -11,12 +11,8 @@ public:
 	void write(uint8_t);
 	void status(const char *s) { Display::status(s); }
 
-protected:
-	static void on_tick();
-
-	void cursor(bool on);
-
 private:
+	void cursor(bool on);
 	void draw(char, int, int);
 
 	static const uint8_t ROWS = 24;