diff --git a/Makefile b/Makefile
index 8b0d09b..b5b2f21 100644
--- a/Makefile
+++ b/Makefile
@@ -3,11 +3,12 @@ CC = gcc
 AS = as
 AR = ar
 OBJCOPY = objcopy
+STRIP = strip
 
 MCUFLAGS = -mthumb -mcpu=cortex-m4 -mfloat-abi=hard -mfpu=fpv4-sp-d16
 AFLAGS = $(MCUFLAGS) 
 CFLAGS = $(MCUFLAGS) -ggdb \
-	-Iinclude -Iinclude/it \
+	-Iinclude -Iinclude/it -Iinclude/cmsis \
 	-fno-builtin -fsigned-char -ffreestanding \
 	-Wall -Werror -Wextra -pedantic \
 	-Wno-overlength-strings -Wno-discarded-qualifiers
@@ -21,13 +22,17 @@ OFILES = $(patsubst src/%.c, $(OUTDIR)/%.o, $(CFILES)) \
 	 $(patsubst src/%.s, $(OUTDIR)/%.asm.o, $(AFILES))
 
 OUT = out/main.elf
+INITRD = initrd.img
 
 all: $(OUT)
 
+#@$(CROSS)$(STRIP) --only-keep-debug $(OUT)
 $(OUT): $(OFILES) initrd/init libinterp.a
+	@echo "  INITRD " $(INITRD)
+	@rm -f $(INITRD)
+	@$(CROSS)$(AR) r $(INITRD) initrd/*
+	@$(CROSS)$(OBJCOPY) -B arm -I binary -O elf32-littlearm $(INITRD) out/initrd.img.o
 	@echo "  LINK   " $(OUT)
-	@./mkinitrd.sh
-	@$(CROSS)$(OBJCOPY) -B arm -I binary -O elf32-littlearm initrd.img out/initrd.img.o
 	@$(CROSS)$(CC) $(CFLAGS) $(LFLAGS) out/*.o -o $(OUT) -L. -linterp
 
 $(OUTDIR)/%.o: src/%.c
diff --git a/include/cmsis_gcc.h b/include/cmsis/cmsis_gcc.h
similarity index 100%
rename from include/cmsis_gcc.h
rename to include/cmsis/cmsis_gcc.h
diff --git a/include/core_cm4.h b/include/cmsis/core_cm4.h
similarity index 100%
rename from include/core_cm4.h
rename to include/cmsis/core_cm4.h
diff --git a/include/core_cmFunc.h b/include/cmsis/core_cmFunc.h
similarity index 100%
rename from include/core_cmFunc.h
rename to include/cmsis/core_cmFunc.h
diff --git a/include/core_cmInstr.h b/include/cmsis/core_cmInstr.h
similarity index 100%
rename from include/core_cmInstr.h
rename to include/cmsis/core_cmInstr.h
diff --git a/include/core_cmSimd.h b/include/cmsis/core_cmSimd.h
similarity index 100%
rename from include/core_cmSimd.h
rename to include/cmsis/core_cmSimd.h
diff --git a/include/gpio.h b/include/gpio.h
index 524b791..46a8e15 100644
--- a/include/gpio.h
+++ b/include/gpio.h
@@ -1,46 +1,116 @@
+/**
+ * @file gpio.h
+ * Abstracts gpio access, makes things easier
+ */
+
 #ifndef GPIO_H_
 #define GPIO_H_
 
 #include <stm32l476xx.h>
 
+/**
+ * Helps simplify gpio calls.
+ * @param p port, e.g. GPIOA
+ * @param b pin, e.g. 4
+ */
 #define GPIO_PORT(p, b) GPIO##p, b
 
+/**
+ * Defines possible modes for a gpio pin
+ */
 enum GPIO_MODE
 {
-	INPUT = 0,
-	OUTPUT,
-	ALTERNATE,
-	ANALOG
+	INPUT = 0, /**< digital input */
+	OUTPUT,    /**< digital output */
+	ALTERNATE, /**< alternate function */
+	ANALOG     /**< analog function */
 };
 
+/**
+ * Defines whether to use push-pull or open drain.
+ */
 enum GPIO_TYPE
 {
-	PUSHPULL = 0,
-	OPENDRAIN
+	PUSHPULL = 0, /**< push-pull */
+	OPENDRAIN     /**< open drain */
 };
 
+/**
+ * Defines the pin's speed
+ */
 enum GPIO_SPEED
 {
-	LOW = 0,
-	MEDIUM,
-	HIGH,
-	VERYHIGH
+	LOW = 0, /**< low */
+	MEDIUM,  /**< medium */
+	HIGH,    /**< high */
+	VERYHIGH /**< very high/maximum */
 };
 
+/**
+ * Defines if a pullup or pulldown should be used.
+ */
 enum GPIO_PUPD
 {
-	NOPUPD,
-	PULLUP,
-	PULLDOWN
+	NOPUPD,  /**< no pullup/pulldown */
+	PULLUP,  /**< use pullup */
+	PULLDOWN /**< use pulldown */
 };
 
+/**
+ * Initializes the gpio.
+ */
 void gpio_init(void);
 
+/**
+ * Enables or disables pullup/pulldown for the given pin.
+ * @param port the port, e.g. GPIOA
+ * @param pin the pin
+ * @param pupd pullup/pulldown enable
+ * @see GPIO_PUPD
+ */
 void gpio_pupd(GPIO_TypeDef *port, uint8_t pin, uint8_t pupd);
+
+/**
+ * Sets whether to use push-pull or open drain for the given pin.
+ * @param port the port
+ * @param pin the pin
+ * @param type what to use
+ * @see GPIO_TYPE
+ */
 void gpio_type(GPIO_TypeDef *port, uint8_t pin, uint8_t type);
+
+/**
+ * Sets the pin's speed.
+ * @param port the port
+ * @param pin the pin
+ * @param speed the speed to use
+ * @see GPIO_SPEED
+ */
 void gpio_speed(GPIO_TypeDef *port, uint8_t pin, uint8_t speed);
+
+/**
+ * Sets the pin's i/o mode.
+ * @param port the port
+ * @param pin the pin
+ * @param mode the mode to use
+ * @see GPIO_MODE
+ */
 void gpio_mode(GPIO_TypeDef *port, uint8_t pin, uint8_t mode);
+
+/**
+ * Sets the state of a digital output pin.
+ * @param port the port
+ * @param pin the pin
+ * @param val non-zero for high, zero for low
+ */
 void gpio_dout(GPIO_TypeDef *port, uint8_t pin, uint8_t val);
+
+/**
+ * Reads a digital input pin.
+ * @param port the port
+ * @param pin the pin
+ * @return non-zero for high, zero for low
+ */
 uint8_t gpio_din(GPIO_TypeDef *port, uint8_t pin);
 
 #endif // GPIO_H_
diff --git a/include/heap.h b/include/heap.h
index c93eb8e..e8cd9c1 100644
--- a/include/heap.h
+++ b/include/heap.h
@@ -1,12 +1,40 @@
+/**
+ * @file heap.h
+ * A basic memory manager
+ */
+
 #ifndef HEAP_H_
 #define HEAP_H_
 
 #include <stdint.h>
 
+/**
+ * Initializes memory management of the given heap.
+ * No overflow stuff is done, so...
+ * @param buf the heap to use for allocations
+ */
 void heap_init(void *buf);
 
+/**
+ * Allocates a chunk of memory.
+ * @param size how many bytes to claim
+ * @return pointer to the allocated buffer
+ */
 void *malloc(uint32_t size);
+
+/**
+ * Allocates and zeros a chunk of memory.
+ * @param count how many of whatever to allocate
+ * @param size byte count of each whatever
+ * @return pointer to the allocated buffer
+ */
 void *calloc(uint32_t count, uint32_t size);
+
+/**
+ * Frees the buffer allocated through malloc/calloc.
+ * Please don't double-free.
+ * @param the buffer to release
+ */
 void free(void *buf);
 
 #endif // HEAP_H_
diff --git a/include/keypad.h b/include/keypad.h
new file mode 100644
index 0000000..83e0626
--- /dev/null
+++ b/include/keypad.h
@@ -0,0 +1,24 @@
+#ifndef KEYPAD_H_
+#define KEYPAD_H_
+
+#include <stdint.h>
+
+#define K0 (1 << 0)
+#define K1 (1 << 1)
+#define K2 (1 << 2)
+#define K3 (1 << 3)
+#define K4 (1 << 4)
+#define K5 (1 << 5)
+#define K6 (1 << 6)
+#define K7 (1 << 7)
+#define K8 (1 << 8)
+#define K9 (1 << 9)
+#define KS (1 << 10)
+#define KP (1 << 11)
+
+void keypad_init(void);
+
+uint16_t keypad_get(void);
+uint8_t keypad_isdown(uint16_t);
+
+#endif // KEYPAD_H_
diff --git a/include/random.h b/include/random.h
index 6485f26..a1868f6 100644
--- a/include/random.h
+++ b/include/random.h
@@ -1,9 +1,22 @@
+/**
+ * @file random.h
+ * Provides true random number generation functionality
+ */
+
 #ifndef RANDOM_H_
 #define RANDOM_H_
 
 #include <stdint.h>
 
+/**
+ * Initializes the STM's true random number generator.
+ */
 void random_init(void);
+
+/**
+ * Gets the next random number from the generator.
+ * @return the random number
+ */
 uint32_t random_get(void);
 
 #endif // RANDOM_H_
diff --git a/include/script.h b/include/script.h
index dc8c590..7901c9c 100644
--- a/include/script.h
+++ b/include/script.h
@@ -1,8 +1,17 @@
+/**
+ * @file script.h
+ * Provides script library for using calculator hardware
+ */
+
 #ifndef SCRIPT_H_
 #define SCRIPT_H_
 
 #include <parser.h>
 
+/**
+ * Loads the library for the given interpreter.
+ * @param it the interpreter to use
+ */
 void script_loadlib(interpreter *it);
 
 #endif // SCRIPT_H_
diff --git a/include/task.h b/include/task.h
index 1ef8639..6456bdc 100644
--- a/include/task.h
+++ b/include/task.h
@@ -28,6 +28,12 @@ void task_init(void (*init)(void));
  */
 void task_start(void (*task)(void), uint16_t stackSize);
 
+/**
+ * Allows task switching to be disabled, for low-level actions.
+ * Multiple holds can be placed, and all must be removed to continue task
+ * switching.
+ * @param hold non-zero for hold, zero to remove hold
+ */
 void task_hold(uint8_t hold);
 
 #endif // TASK_H_
diff --git a/initrd/init b/initrd/init
index 9f6a9cf..fcf9ec2 100644
--- a/initrd/init
+++ b/initrd/init
@@ -1,11 +1,14 @@
 do
-	rand 479 > x
-	rand 319 > y
-	rand 479 > i
-	rand 319 > j
-	rand 32767 > purple
+	getkey > input
+	if (input & 4)
+		rand 479 > x
+		rand 319 > y
+		rand 479 > i
+		rand 319 > j
+		rand 32767 > purple
 		
-	line x y i j purple
+		line x y i j purple
+	end
 while (1)
 
 print "done"
diff --git a/mkinitrd.sh b/mkinitrd.sh
deleted file mode 100755
index eb47fd8..0000000
--- a/mkinitrd.sh
+++ /dev/null
@@ -1,4 +0,0 @@
-#!/bin/bash
-echo "Making initrd.img..."
-rm -f initrd.img
-arm-none-eabi-ar r initrd.img initrd/*
diff --git a/src/clock.c b/src/clock.c
index 3d31f91..0c8ca7c 100644
--- a/src/clock.c
+++ b/src/clock.c
@@ -7,7 +7,7 @@
 #define STK_CALIB	*((uint32_t *)0xE000E01C)
 
 // ticks since init
-static uint32_t ticks = 0;
+volatile uint32_t ticks = 0;
 
 void clock_init(void)
 {
@@ -31,6 +31,7 @@ void clock_init(void)
 
 	// set system clock to PLL
 	RCC->CFGR &= ~(RCC_CFGR_SW);
+	RCC->CFGR &= ~(RCC_CFGR_HPRE_Msk);
 	RCC->CFGR |= RCC_CFGR_SW_PLL;
 	while ((RCC->CFGR & RCC_CFGR_SWS_PLL) != RCC_CFGR_SWS_PLL);
 
@@ -45,18 +46,12 @@ void delay(uint32_t count)
 	while (ticks < target);
 }
 
-__attribute__ ((naked))
 void SysTick_Handler(void)
 {
-	uint32_t lr;
-	asm("mov %0, lr" : "=r" (lr));
-
 	// just keep counting
 	ticks++;
 
 	if (!(ticks & 3))
 		SCB->ICSR |= SCB_ICSR_PENDSVSET_Msk;
-
-	asm("mov lr, %0; bx lr" :: "r" (lr));
 }
 
diff --git a/src/display_draw.c b/src/display_draw.c
index 27ed796..a315bf7 100644
--- a/src/display_draw.c
+++ b/src/display_draw.c
@@ -92,12 +92,12 @@ void dsp_rect(int x, int y, int w, int h, uint16_t color)
 {
 	dsp_set_addr(x, y, x + w - 1, y + h - 1);
 	int countdown = w * h;
+	LOCK;
 	do {
-		LOCK;
 		dsp_write_data(color >> 8);
 		dsp_write_data(color & 0xFF);
-		UNLOCK;
 	} while (countdown--);
+	UNLOCK;
 }
 
 void dsp_line(int x, int y, int i, int j, uint16_t color)
diff --git a/src/gpio.c b/src/gpio.c
index c2617ee..900a3f1 100644
--- a/src/gpio.c
+++ b/src/gpio.c
@@ -32,10 +32,7 @@ void gpio_mode(GPIO_TypeDef *port, uint8_t pin, uint8_t mode)
 
 void gpio_dout(GPIO_TypeDef *port, uint8_t pin, uint8_t val)
 {
-	if (val)
-		port->BSRR |= (1 << pin);
-	else
-		port->BRR |= (1 << pin);
+	port->BSRR |= (1 << (val ? pin : pin + 16));
 }
 
 uint8_t gpio_din(GPIO_TypeDef *port, uint8_t pin)
diff --git a/src/keypad.c b/src/keypad.c
new file mode 100644
index 0000000..41fc924
--- /dev/null
+++ b/src/keypad.c
@@ -0,0 +1,63 @@
+#include <keypad.h>
+#include <gpio.h>
+
+#define PIN_0 GPIO_PORT(A, 11)
+#define PIN_1 GPIO_PORT(B, 13)
+#define PIN_2 GPIO_PORT(B, 2)
+#define PIN_3 GPIO_PORT(A, 12)
+#define PIN_4 GPIO_PORT(B, 14)
+#define PIN_5 GPIO_PORT(B, 11)
+#define PIN_6 GPIO_PORT(C, 5)
+#define PIN_7 GPIO_PORT(B, 15)
+#define PIN_8 GPIO_PORT(B, 12)
+#define PIN_9 GPIO_PORT(C, 6)
+#define PIN_S GPIO_PORT(B, 1)
+#define PIN_P GPIO_PORT(C, 8)
+
+typedef struct {
+	GPIO_TypeDef *port;
+	uint16_t pin;
+	uint16_t keycode;
+} key_t;
+
+static const key_t keypad_map[12] = {
+	{ PIN_0, K0 },
+	{ PIN_1, K1 },
+	{ PIN_2, K2 },
+	{ PIN_3, K3 },
+	{ PIN_4, K4 },
+	{ PIN_5, K5 },
+	{ PIN_6, K6 },
+	{ PIN_7, K7 },
+	{ PIN_8, K8 },
+	{ PIN_9, K9 },
+	{ PIN_S, KS },
+	{ PIN_P, KP }
+};
+
+void keypad_init(void)
+{
+	for (uint8_t i = 0; i < 12; i++) {
+		GPIO_TypeDef *p = keypad_map[i].port;
+		uint16_t pin = keypad_map[i].pin;
+		gpio_mode(p, pin, OUTPUT);
+		gpio_dout(p, pin, 0);
+		gpio_mode(p, pin, INPUT);
+		gpio_pupd(p, pin, PULLDOWN);
+	}
+}
+
+uint16_t keypad_get(void)
+{
+	uint16_t state = 0;
+	for (uint8_t i = 0; i < 12; i++) {
+		if (gpio_din(keypad_map[i].port, keypad_map[i].pin))
+			state |= keypad_map[i].keycode;
+	}
+	return state;
+}
+
+uint8_t keypad_isdown(uint16_t keycode)
+{
+	return (keypad_get() & keycode);
+}
diff --git a/src/main.c b/src/main.c
index 54c2403..abcb8e6 100644
--- a/src/main.c
+++ b/src/main.c
@@ -12,6 +12,7 @@
 #include <string.h>
 #include <script.h>
 #include <random.h>
+#include <keypad.h>
 
 extern uint8_t _ebss;
 extern char *itoa(int, char *, int);
@@ -22,24 +23,27 @@ void task_interpreter(void);
 int main(void)
 {
 	asm("cpsid i");
-	// disable write buffer
-	*((uint32_t *)0xE000E008) |= 2;
 
 	// prepare flash latency for 80MHz operation
 	FLASH->ACR &= ~(FLASH_ACR_LATENCY);
 	FLASH->ACR |= FLASH_ACR_LATENCY_4WS;
 
-	//MPU->CTRL |= MPU_CTRL_ENABLE_Msk | MPU_CTRL_PRIVDEFENA_Msk;
 	clock_init();
 	heap_init(&_ebss);
 	gpio_init();
+	keypad_init();
 	serial_init();
 	random_init();
 
+	//extern void keypad_init(void);
+	//keypad_init();
+
 	gpio_mode(GPIOA, 5, OUTPUT);
 
 	// enable FPU
 	SCB->CPACR |= (0xF << 20);
+	// enable MPU
+	//MPU->CTRL |= MPU_CTRL_PRIVDEFENA_Msk | MPU_CTRL_ENABLE_Msk;
 
 	task_init(kmain);
 	while (1);
@@ -47,17 +51,18 @@ int main(void)
 
 void kmain(void)
 {
-	asm("cpsie i");
 	dsp_init();
 	dsp_rect(0, 0, LCD_WIDTH, LCD_HEIGHT, dsp_color(0, 0, 0));
 	dsp_cursoron();
 	task_start(task_interpreter, 4096);
 
 	while (1) {
-		gpio_dout(GPIOA, 5, 1);
+		gpio_dout(GPIOA, 5,
+			(keypad_isdown(K0)));
+		/*gpio_dout(GPIOA, 5, 1);
 		delay(250);
 		gpio_dout(GPIOA, 5, 0);
-		delay(250);
+		delay(250);*/
 	}
 }
 
diff --git a/src/script.c b/src/script.c
index adf402b..78165b0 100644
--- a/src/script.c
+++ b/src/script.c
@@ -8,6 +8,7 @@
 #include <random.h>
 #include <serial.h>
 #include <stack.h>
+#include <keypad.h>
 
 int script_puts(interpreter *it);
 int script_gets(interpreter *it);
@@ -17,6 +18,7 @@ int script_ppos(interpreter *it);
 int script_line(interpreter *it);
 int script_color(interpreter *it);
 int script_rand(interpreter *it);
+int script_getkey(interpreter *it);
 
 void script_loadlib(interpreter *it)
 {
@@ -28,6 +30,7 @@ void script_loadlib(interpreter *it)
 	inew_cfunc(it, "line", script_line);
 	inew_cfunc(it, "color", script_color);
 	inew_cfunc(it, "rand", script_rand);
+	inew_cfunc(it, "getkey", script_getkey);
 }
 
 int script_puts(interpreter *it)
@@ -118,3 +121,16 @@ int script_rand(interpreter *it)
 	free(v);
 	return 0;
 }
+
+int script_getkey(interpreter *it)
+{
+	variable *v = (variable *)malloc(sizeof(variable));
+	v->valtype = INTEGER;
+	INT(v) = keypad_get();
+	v->svalue = 0;
+	isetstr(v);
+	iret(it, v);
+	free(v->svalue);
+	free(v);
+	return 0;
+}
diff --git a/src/stm32l4xx_it.c b/src/stm32l4xx_it.c
index f643db3..e54a192 100644
--- a/src/stm32l4xx_it.c
+++ b/src/stm32l4xx_it.c
@@ -12,12 +12,12 @@ void serial_puts(const char *s)
 
 void perror(const char *s)
 {
-	extern task_t *current;
+	//extern task_t *current;
 	serial_puts(s);
-	char buf[200];
-	snprintf(buf, 200, "xPSR: %x\r\nPC: %x\r\nLR: %x\r\n", current->sp[0],
-		current->sp[1], current->sp[2]);
-	serial_puts(buf);
+	//char buf[200];
+	//snprintf(buf, 200, "xPSR: %x\r\nPC: %x\r\nLR: %x\r\n", current->sp[0],
+	//	current->sp[1], current->sp[2]);
+	//serial_puts(buf);
 }
 
 __attribute__ ((naked))
@@ -27,7 +27,7 @@ __attribute__ ((naked))
 void HardFault_Handler(void)
 {
 	GPIOA->BSRR |= (1 << 5);
-	//perror("Hard Fault!");
+	perror("Hard Fault!");
 	while (1);
 }
 
diff --git a/src/task.c b/src/task.c
index 6a755de..537785d 100644
--- a/src/task.c
+++ b/src/task.c
@@ -34,12 +34,6 @@ task_t *task_create(void (*code)(void), uint32_t stackSize)
 	t->sp[14] = 0xFFFFFFFD;
 	t->sp[15] = (uint32_t)code;
 	t->sp[16] = 0x01000000;
-
-	//void *sp = (uint8_t *)t->stack + stackSize - 64; // 16 words
-	//t->sp = (uint32_t *)sp;
-	//t->sp[13] = (uint32_t)task_exit;
-	//t->sp[14] = (uint32_t)code;
-	//t->sp[15] = 0x01000000;
 	return t;
 }
 
@@ -53,7 +47,8 @@ void task_init(void (*init)(void))
 	asm("\
 		msr psp, %0; \
 		mrs r0, control; \
-		orr r0, r0, #2; \
+		orr r0, r0, #3; \
+		cpsie i; \
 		msr control, r0; \
 		isb; \
 		bx %1; \