diff --git a/src/bus.c b/src/bus.c
index b554b64..3a147b3 100644
--- a/src/bus.c
+++ b/src/bus.c
@@ -141,7 +141,7 @@ void bus_io_out(ceda_ioaddr_t _address, uint8_t value) {
     ubus_io_out(address, value);
 }
 
-void bus_init(CEDAModule *mod) {
+static void bus_prepareFirstAccess(void) {
     // when starting, BIOS ROM is mounted at 0x0,
     // until the first I/O access is performed,
     // but we'll just emulate this behaviour with an equivalent
@@ -150,8 +150,19 @@ void bus_init(CEDAModule *mod) {
     for (uint8_t address = 0; address < (uint8_t)ARRAY_SIZE(jmp); ++address) {
         dyn_ram_write(address, jmp[address]);
     }
+}
+
+static bool bus_restart(void) {
+    is_mem_switched = false;
+    bus_prepareFirstAccess();
+    return true;
+}
 
+void bus_init(CEDAModule *mod) {
     memset(mod, 0, sizeof(*mod));
+    mod->restart = bus_restart;
+
+    bus_prepareFirstAccess();
 }
 
 void bus_memSwitch(bool switched) {
diff --git a/src/ceda.c b/src/ceda.c
index c6f68ad..84b57d4 100644
--- a/src/ceda.c
+++ b/src/ceda.c
@@ -15,6 +15,7 @@
 #include "serial.h"
 #include "sio2.h"
 #include "speaker.h"
+#include "timer.h"
 #include "ubus.h"
 #include "upd8255.h"
 #include "video.h"
@@ -30,19 +31,23 @@
 static CEDAModule mod_bios;
 static CEDAModule mod_bus;
 static CEDAModule mod_cpu;
+static CEDAModule mod_charmon;
 static CEDAModule mod_cli;
+static CEDAModule mod_fdc;
 static CEDAModule mod_gui;
-static CEDAModule mod_video;
-static CEDAModule mod_speaker;
-static CEDAModule mod_sio2;
 static CEDAModule mod_int;
 static CEDAModule mod_serial;
+static CEDAModule mod_speaker;
+static CEDAModule mod_sio2;
+static CEDAModule mod_timer;
 static CEDAModule mod_ubus;
-static CEDAModule mod_charmon;
+static CEDAModule mod_upd8255;
+static CEDAModule mod_video;
 
 static CEDAModule *modules[] = {
-    &mod_bios,    &mod_cli, &mod_gui,    &mod_bus,  &mod_cpu,  &mod_video,
-    &mod_speaker, &mod_int, &mod_serial, &mod_sio2, &mod_ubus, &mod_charmon,
+    &mod_bios,  &mod_cli,     &mod_gui, &mod_bus,   &mod_cpu,
+    &mod_video, &mod_speaker, &mod_int, &mod_timer, &mod_serial,
+    &mod_sio2,  &mod_upd8255, &mod_fdc, &mod_ubus,  &mod_charmon,
 };
 
 void ceda_init(void) {
@@ -50,8 +55,8 @@ void ceda_init(void) {
     cli_init(&mod_cli);
     gui_init(&mod_gui);
 
-    fdc_init();
-    upd8255_init();
+    fdc_init(&mod_fdc);
+    upd8255_init(&mod_upd8255);
     rom_bios_init(&mod_bios);
     video_init(&mod_video);
     speaker_init(&mod_speaker);
@@ -60,6 +65,7 @@ void ceda_init(void) {
     bus_init(&mod_bus);
     cpu_init(&mod_cpu);
     int_init(&mod_int);
+    timer_init(&mod_timer);
     serial_init(&mod_serial);
     sio2_init(&mod_sio2);
 }
@@ -112,6 +118,21 @@ static void ceda_performance(void) {
     }
 }
 
+static bool ceda_restart(void) {
+    bool ret = false;
+    for (unsigned int i = 0; i < ARRAY_SIZE(modules); ++i) {
+        bool (*restart)(void) = modules[i]->restart;
+        if (!restart)
+            continue;
+        ret = restart();
+        if (!ret) {
+            LOG_ERR("module %u: restart error\n", i);
+            break;
+        }
+    }
+    return ret;
+}
+
 static void ceda_cleanup(void) {
     for (int i = ARRAY_SIZE(modules) - 1; i >= 0; --i) {
         void (*cleanup)(void) = modules[i]->cleanup;
@@ -140,6 +161,10 @@ int ceda_run(void) {
         if (gui_isQuit() || cli_isQuit()) {
             break;
         }
+        if (cli_checkRestart()) {
+            if (!ceda_restart())
+                break;
+        }
 
         // check for how long each module can sleep, and yield host cpu
         ceda_remaining();
diff --git a/src/cli.c b/src/cli.c
index afcdd8d..330cd9f 100644
--- a/src/cli.c
+++ b/src/cli.c
@@ -37,6 +37,7 @@ enum { BLOCK_BUFFER_SIZE = 4096 }; // big page-like stuff
 
 static bool initialized = false;
 static bool quit = false;
+static bool restart = false;
 static const us_interval_t UPDATE_INTERVAL = 20000; // [us] 20 ms => 50 Hz
 static us_time_t last_update = 0;                   // last poll() call
 
@@ -50,6 +51,12 @@ bool cli_isQuit(void) {
     return quit;
 }
 
+bool cli_checkRestart(void) {
+    bool prev = restart;
+    restart = false;
+    return prev;
+}
+
 /**
  * @brief Send a string to the connected client.
  *
@@ -696,6 +703,12 @@ static ceda_string_t *cli_int(const char *arg) {
     return NULL;
 }
 
+static ceda_string_t *cli_reset(const char *arg) {
+    (void)arg;
+    restart = true;
+    return NULL;
+}
+
 static ceda_string_t *cli_in(const char *arg) {
     char word[LINE_BUFFER_SIZE];
     ceda_string_t *msg = ceda_string_new(0);
@@ -815,6 +828,7 @@ static const cli_command cli_commands[] = {
     {"step", "step one instruction", cli_step},
     {"goto", "override cpu program counter", cli_goto},
     {"int", "trigger interrupt request", cli_int},
+    {"reset", "perform an hard reset", cli_reset},
     {"read", "read from memory", cli_read},
     {"write", "write to memory", cli_write},
     {"in", "read from io", cli_in},
diff --git a/src/cli.h b/src/cli.h
index 5710adb..f03f743 100644
--- a/src/cli.h
+++ b/src/cli.h
@@ -9,4 +9,13 @@ void cli_init(CEDAModule *mod);
 
 bool cli_isQuit(void);
 
+/**
+ * @brief Check if the computer must be restarted (cold hard reset).
+ *
+ * The restart value is automatically reset upon read.
+ *
+ * @return true if must be restarted, false otherwise.
+ */
+bool cli_checkRestart(void);
+
 #endif // CEDA_CLI_H
diff --git a/src/cpu.c b/src/cpu.c
index c30ae2d..a36c288 100644
--- a/src/cpu.c
+++ b/src/cpu.c
@@ -207,6 +207,16 @@ static uint8_t cpu_int_read(void *context, zuint16 address) {
     return int_pop();
 }
 
+static void cpu_cleanup(void) {
+    z80_power(&cpu, false);
+}
+
+static bool cpu_restart(void) {
+    cpu_cleanup();
+    z80_power(&cpu, true);
+    return true;
+}
+
 void cpu_init(CEDAModule *mod) {
     // init mod struct
     memset(mod, 0, sizeof(*mod));
@@ -214,7 +224,8 @@ void cpu_init(CEDAModule *mod) {
     mod->start = NULL;
     mod->poll = cpu_poll;
     mod->remaining = cpu_remaining;
-    mod->cleanup = NULL;
+    mod->cleanup = cpu_cleanup;
+    mod->restart = cpu_restart;
     mod->performance = cpu_performance;
 
     // init cpu
diff --git a/src/crtc.c b/src/crtc.c
index bab5ee9..9e5e0f0 100644
--- a/src/crtc.c
+++ b/src/crtc.c
@@ -2,6 +2,7 @@
 
 #include <assert.h>
 #include <stdint.h>
+#include <string.h>
 
 #include "video.h"
 
@@ -27,14 +28,10 @@ static uint8_t regs[CRTC_REGISTER_COUNT];
 #define REG_CURSOR_L                       15
 #define REG_LIGHT_PEN_H                    16
 #define REG_LIGHT_PEN_L                    17
-unsigned int rselect = 0; // current register selected
+static unsigned int rselect = 0; // current register selected
 
 #define CRTC_NOT_IMPLEMENTED_STR "not implemented\n"
 
-void crtc_init(void) {
-    // TODO(giomba): missing initialization
-}
-
 uint8_t crtc_in(ceda_ioaddr_t address) {
     (void)address;
 
@@ -139,3 +136,15 @@ uint16_t crtc_startAddress(void) {
 
     return start_address;
 }
+
+static bool crtc_restart(void) {
+    memset(&regs, 0, sizeof(regs));
+    rselect = 0;
+    return true;
+}
+
+void crtc_init(CEDAModule *mod) {
+    memset(mod, 0, sizeof(*mod));
+    mod->init = crtc_init;
+    mod->restart = crtc_restart;
+}
diff --git a/src/crtc.h b/src/crtc.h
index e8a6175..a26a02b 100644
--- a/src/crtc.h
+++ b/src/crtc.h
@@ -1,6 +1,7 @@
 #ifndef CEDA_CRTC_H
 #define CEDA_CRTC_H
 
+#include "module.h"
 #include "type.h"
 
 #include <Z80.h>
@@ -12,7 +13,7 @@ typedef enum CRTCCursorBlink {
     CRTC_CURSOR_BLINK_FAST,
 } CRTCCursorBlink;
 
-void crtc_init(void);
+void crtc_init(CEDAModule *mod);
 
 uint8_t crtc_in(ceda_ioaddr_t address);
 void crtc_out(ceda_ioaddr_t address, uint8_t value);
diff --git a/src/fdc.c b/src/fdc.c
index 4edeb4a..ce738be 100644
--- a/src/fdc.c
+++ b/src/fdc.c
@@ -911,9 +911,7 @@ static bool fdc_commit_write(void) {
     return false;
 }
 
-/* * * * * * * * * * * * * * *  Public routines   * * * * * * * * * * * * * * */
-
-void fdc_init(void) {
+static bool fdc_restart(void) {
     // Reset current command status
     fdc_status = CMD;
     fdc_currop = NULL;
@@ -931,9 +929,17 @@ void fdc_init(void) {
     // Reset track positions
     memset(track, 0, sizeof(track));
 
-    // Detach any read/write callback
-    read_buffer_cb = NULL;
-    write_buffer_cb = NULL;
+    return true;
+}
+
+/* * * * * * * * * * * * * * *  Public routines   * * * * * * * * * * * * * * */
+
+void fdc_init(CEDAModule *mod) {
+    memset(mod, 0, sizeof(*mod));
+    mod->init = fdc_init;
+    mod->restart = fdc_restart;
+
+    fdc_restart();
 }
 
 uint8_t fdc_in(ceda_ioaddr_t address) {
diff --git a/src/fdc.h b/src/fdc.h
index 5183bdb..6a3bdf8 100644
--- a/src/fdc.h
+++ b/src/fdc.h
@@ -1,6 +1,7 @@
 #ifndef CEDA_FDC_H
 #define CEDA_FDC_H
 
+#include "module.h"
 #include "type.h"
 
 #include <Z80.h>
@@ -30,7 +31,7 @@ typedef int (*fdc_read_write_t)(uint8_t *buffer, uint8_t unit_number,
  * @brief Initialize the Floppy Disk Controller system
  *
  */
-void fdc_init(void);
+void fdc_init(CEDAModule *mod);
 
 /**
  * @brief Read data from the Floppy Disk Controller using its bus
diff --git a/src/module.h b/src/module.h
index 2d2d1cd..e012383 100644
--- a/src/module.h
+++ b/src/module.h
@@ -35,6 +35,20 @@ typedef struct CEDAModule {
      */
     bool (*start)(void);
 
+    /**
+     * @brief Restart a module.
+     *
+     * This routine is used to implement the "reset" functionality of a module.
+     *
+     * This routine should perform a suitable module cleanup (eg. release
+     * dynamically acquired resources), and then the subsequent proper restart
+     * (eg. reinitialize variables, reacquire dynamic resources, etc...).
+     *
+     * Return true in case of success, false otherwise.
+     *
+     */
+    bool (*restart)(void);
+
     /**
      * @brief Advance the internal status of the module.
      *
diff --git a/src/sio2.c b/src/sio2.c
index ec83845..cebdb3a 100644
--- a/src/sio2.c
+++ b/src/sio2.c
@@ -426,16 +426,23 @@ void sio2_detachPeripheral(sio_channel_idx_t channel) {
     channels[channel].putc = NULL;
 }
 
+static bool sio2_restart(void) {
+    for (size_t i = 0; i < ARRAY_SIZE(channels); ++i)
+        sio_channel_init(&channels[i]);
+
+    // attach keyboard to channel B
+    channels[SIO_CHANNEL_B].getc = keyboard_getChar;
+
+    return true;
+}
+
 void sio2_init(CEDAModule *mod) {
     mod->init = sio2_init;
     mod->start = sio2_start;
+    mod->restart = sio2_restart;
     mod->poll = sio2_poll;
     mod->remaining = sio2_remaining;
     mod->cleanup = sio2_cleanup;
 
-    for (size_t i = 0; i < ARRAY_SIZE(channels); ++i)
-        sio_channel_init(&channels[i]);
-
-    // attach keyboard to channel B
-    channels[SIO_CHANNEL_B].getc = keyboard_getChar;
+    sio2_restart();
 }
diff --git a/src/tests/test_fdc.c b/src/tests/test_fdc.c
index 92eb9c8..2d9e54f 100644
--- a/src/tests/test_fdc.c
+++ b/src/tests/test_fdc.c
@@ -6,6 +6,7 @@
 // TODO(giuliof) source path is src!
 #include "../fdc.h"
 #include "../fdc_registers.h"
+#include "../module.h"
 
 static void assert_fdc_sr(uint8_t expected_sr);
 static int fake_read(uint8_t *buffer, uint8_t unit_number, bool phy_head,
@@ -77,14 +78,16 @@ static int fake_read_check_track(uint8_t *buffer, uint8_t unit_number,
 }
 
 Test(ceda_fdc, mainStatusRegisterWhenIdle) {
-    fdc_init();
+    CEDAModule mod;
+    fdc_init(&mod);
 
     // Try to read status register and check that it is idle
     assert_fdc_sr(FDC_ST_RQM);
 }
 
 Test(ceda_fdc, specifyCommand) {
-    fdc_init();
+    CEDAModule mod;
+    fdc_init(&mod);
 
     // Try to read status register and check that it is idle
     fdc_out(FDC_ADDR_DATA_REGISTER, FDC_SPECIFY);
@@ -101,7 +104,8 @@ Test(ceda_fdc, specifyCommand) {
 }
 
 Test(ceda_fdc, seekCommand) {
-    fdc_init();
+    CEDAModule mod;
+    fdc_init(&mod);
 
     uint8_t data;
 
@@ -150,7 +154,8 @@ Test(ceda_fdc, seekCommand) {
  * be an Invalid Command" (see invalidCommand test).
  */
 Test(ceda_fdc, invalidSeekSequence) {
-    fdc_init();
+    CEDAModule mod;
+    fdc_init(&mod);
 
     uint8_t data;
 
@@ -222,7 +227,8 @@ Test(ceda_fdc, readCommandNoMedium) {
         4, // DTL
     };
 
-    fdc_init();
+    CEDAModule mod;
+    fdc_init(&mod);
 
     fdc_out(FDC_ADDR_DATA_REGISTER, FDC_READ_DATA);
 
@@ -269,7 +275,8 @@ Test(ceda_fdc, readCommandInvalidParams) {
 
     uint8_t result[sizeof(expected_result)];
 
-    fdc_init();
+    CEDAModule mod;
+    fdc_init(&mod);
 
     // Link a fake reading function
     fdc_kickDiskImage(fake_wrong_rw, NULL);
@@ -317,7 +324,8 @@ Test(ceda_fdc, readCommandOverEot) {
 
     uint8_t result[sizeof(expected_result)];
 
-    fdc_init();
+    CEDAModule mod;
+    fdc_init(&mod);
 
     // Link a fake reading function
     fdc_kickDiskImage(fake_read_check_track, NULL);
@@ -562,7 +570,8 @@ ParameterizedTestParameters(ceda_fdc, readCommand0) {
 ParameterizedTest(struct rw_test_params_t *param, ceda_fdc, readCommand0) {
     uint8_t result[sizeof(param->result)];
 
-    fdc_init();
+    CEDAModule mod;
+    fdc_init(&mod);
 
     // Link a fake reading function
     fdc_kickDiskImage(fake_read, NULL);
@@ -629,7 +638,8 @@ ParameterizedTestParameters(ceda_fdc, writeCommand0) {
 ParameterizedTest(struct rw_test_params_t *param, ceda_fdc, writeCommand0) {
     uint8_t result[sizeof(param->result)];
 
-    fdc_init();
+    CEDAModule mod;
+    fdc_init(&mod);
 
     // Link a fake reading function
     fdc_kickDiskImage(NULL, fake_write);
@@ -696,7 +706,8 @@ Test(ceda_fdc, writeCommandInvalidParams) {
 
     uint8_t result[sizeof(expected_result)];
 
-    fdc_init();
+    CEDAModule mod;
+    fdc_init(&mod);
 
     // Link a fake reading function
     fdc_kickDiskImage(NULL, fake_wrong_rw);
@@ -739,7 +750,8 @@ Test(ceda_fdc, formatCommand) {
 
     uint8_t result[7];
 
-    fdc_init();
+    CEDAModule mod;
+    fdc_init(&mod);
 
     // Link a fake reading function
     fdc_kickDiskImage(NULL, fake_write);
@@ -799,7 +811,8 @@ Test(ceda_fdc, formatCommandInvalidParams) {
 
     uint8_t result[7];
 
-    fdc_init();
+    CEDAModule mod;
+    fdc_init(&mod);
 
     // Link a fake reading function
     fdc_kickDiskImage(NULL, fake_wrong_rw);
@@ -839,7 +852,8 @@ Test(ceda_fdc, formatCommandInvalidParams) {
 Test(ceda_fdc, invalidCommand) {
     uint8_t st0;
 
-    fdc_init();
+    CEDAModule mod;
+    fdc_init(&mod);
 
     // Force an invalid command
     fdc_out(FDC_ADDR_DATA_REGISTER, 0x00);
diff --git a/src/timer.c b/src/timer.c
index 6986ef6..d37d906 100644
--- a/src/timer.c
+++ b/src/timer.c
@@ -1,8 +1,6 @@
 #include "timer.h"
 
-void timer_init() {
-    // TODO(giomba)
-}
+#include <string.h>
 
 uint8_t timer_in(ceda_ioaddr_t address) {
     // TODO(giomba)
@@ -15,4 +13,16 @@ void timer_out(ceda_ioaddr_t address, uint8_t value) {
     // TODO(giomba)
     (void)address;
     (void)value;
-}
\ No newline at end of file
+}
+
+static bool timer_restart(void) {
+    // TODO(giomba): implement me
+    return true;
+}
+
+void timer_init(CEDAModule *mod) {
+    memset(mod, 0, sizeof(*mod));
+    mod->init = timer_init;
+    mod->restart = timer_restart;
+    // TODO(giomba)
+}
diff --git a/src/timer.h b/src/timer.h
index 3912597..e2e8ef4 100644
--- a/src/timer.h
+++ b/src/timer.h
@@ -1,11 +1,12 @@
 #ifndef CEDA_TIMER_H
 #define CEDA_TIMER_H
 
+#include "module.h"
 #include "type.h"
 
 #include <Z80.h>
 
-void timer_init();
+void timer_init(CEDAModule *mod);
 
 uint8_t timer_in(ceda_ioaddr_t address);
 void timer_out(ceda_ioaddr_t address, uint8_t value);
diff --git a/src/upd8255.c b/src/upd8255.c
index 823614d..b2b9d35 100644
--- a/src/upd8255.c
+++ b/src/upd8255.c
@@ -6,6 +6,7 @@
 
 #include <assert.h>
 #include <stdint.h>
+#include <string.h>
 
 #include "log.h"
 
@@ -14,15 +15,11 @@
 #define UPD8255_PORTC_REG 2
 
 #define UPD8255_PORTS_COUNT 3
-uint8_t port[UPD8255_PORTS_COUNT];
+static uint8_t port[UPD8255_PORTS_COUNT];
 #define UPD8255_CONTROL_REG 3
 
 #define UPD8255_REG_COUNT 4
 
-void upd8255_init(void) {
-    ;
-}
-
 uint8_t upd8255_in(ceda_ioaddr_t address) {
     assert(address < UPD8255_REG_COUNT);
 
@@ -76,3 +73,14 @@ void upd8255_out(ceda_ioaddr_t address, uint8_t value) {
 
     assert(0);
 }
+
+static bool upd8255_restart(void) {
+    memset(&port, 0, sizeof(port));
+    return true;
+}
+
+void upd8255_init(CEDAModule *mod) {
+    memset(mod, 0, sizeof(*mod));
+    mod->init = upd8255_init;
+    mod->restart = upd8255_restart;
+}
diff --git a/src/upd8255.h b/src/upd8255.h
index 4e7c3aa..4397dd6 100644
--- a/src/upd8255.h
+++ b/src/upd8255.h
@@ -1,11 +1,12 @@
 #ifndef CEDA_UPD8255_H
 #define CEDA_UPD8255_H
 
+#include "module.h"
 #include "type.h"
 
 #include <Z80.h>
 
-void upd8255_init(void);
+void upd8255_init(CEDAModule *mod);
 
 uint8_t upd8255_in(ceda_ioaddr_t address);
 void upd8255_out(ceda_ioaddr_t address, uint8_t value);
diff --git a/src/video.c b/src/video.c
index e21158f..8f62878 100644
--- a/src/video.c
+++ b/src/video.c
@@ -379,18 +379,24 @@ static us_time_t video_remaining(void) {
     return diff;
 }
 
+static bool video_restart(void) {
+    // default to character memory
+    mem = mem_char;
+    return true;
+}
+
 void video_init(CEDAModule *mod) {
     // mod init
     memset(mod, 0, sizeof(*mod));
     mod->init = video_init;
     mod->start = video_start;
+    mod->restart = video_restart;
     mod->poll = video_poll;
     mod->remaining = video_remaining;
     mod->cleanup = NULL;
     mod->performance = video_performance;
 
-    // default to character memory
-    mem = mem_char;
+    video_restart();
 }
 
 zuint8 video_ram_read(ceda_address_t address) {