diff --git a/docs/ibm_43p.cfg b/docs/ibm_43p.cfg
index 70bbfdb..653d50b 100644
--- a/docs/ibm_43p.cfg
+++ b/docs/ibm_43p.cfg
@@ -36,3 +36,8 @@
   iobase = "0x170"
   iobase2 = "0x376"
   irq = "15"
+
+[device]
+  driver = "prep-systemio"
+  ibm-planar-id = "0xc0"
+  equipment = "0xff"
diff --git a/hw/ppc/Makefile.objs b/hw/ppc/Makefile.objs
index be00d1d..cd1eb1b 100644
--- a/hw/ppc/Makefile.objs
+++ b/hw/ppc/Makefile.objs
@@ -9,6 +9,7 @@ obj-y += ppc405_boards.o ppc4xx_devs.o ppc405_uc.o ppc440_bamboo.o
 obj-y += ppc4xx_pci.o
 # PReP
 obj-y += prep.o
+obj-y += prep_systemio.o
 # OldWorld PowerMac
 obj-y += mac_oldworld.o
 # NewWorld PowerMac
diff --git a/hw/ppc/prep_systemio.c b/hw/ppc/prep_systemio.c
new file mode 100644
index 0000000..1ea511c
--- /dev/null
+++ b/hw/ppc/prep_systemio.c
@@ -0,0 +1,298 @@
+/*
+ * QEMU PReP System I/O emulation
+ *
+ * Copyright (c) 2003-2007 Jocelyn Mayer
+ * Copyright (c) 2010-2012 Herve Poussineau
+ * Copyright (c) 2010-2011 Andreas Faerber
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "hw/isa/isa.h"
+#include "exec/address-spaces.h"
+#include "qemu/error-report.h" /* for error_report() */
+#include "sysemu/sysemu.h" /* for vm_stop() */
+#include "trace.h"
+
+#define TYPE_PREP_SYSTEMIO "prep-systemio"
+#define PREP_SYSTEMIO(obj) \
+    OBJECT_CHECK(PrepSystemIoState, (obj), TYPE_PREP_SYSTEMIO)
+
+/* Bit as defined in PowerPC Reference Plaform v1.1, sect. 6.1.5, p. 132 */
+#define BIT(n) (1 << (7 - (n)))
+
+typedef struct PrepSystemIoState {
+    ISADevice parent_obj;
+    MemoryRegion ppc_parity_mem;
+
+    qemu_irq non_contiguous_io_map_irq;
+    uint8_t sreset; /* 0x0092 */
+    uint8_t equipment; /* 0x080c */
+    uint8_t system_control; /* 0x081c */
+    uint8_t iomap_type; /* 0x0850 */
+    uint8_t ibm_planar_id; /* 0x0852 */
+    qemu_irq softreset_irq;
+} PrepSystemIoState;
+
+/* PORT 0092 -- Special Port 92 (Read/Write) */
+
+enum {
+    PORT0092_SOFTRESET  = BIT(7),
+    PORT0092_LE_MODE    = BIT(6),
+};
+
+static void prep_port0092_write(void *opaque, uint32_t addr, uint32_t val)
+{
+    PrepSystemIoState *s = opaque;
+
+    trace_prep_systemio_write(addr, val);
+
+    if ((val & PORT0092_SOFTRESET) != 0) {
+        qemu_irq_raise(s->softreset_irq);
+        s->sreset = 1;
+    } else {
+        qemu_irq_lower(s->softreset_irq);
+        s->sreset = 0;
+    }
+
+    if ((val & PORT0092_LE_MODE) != 0) {
+        /* XXX Not supported yet */
+        error_report("little-endian mode not supported");
+        vm_stop(RUN_STATE_PAUSED);
+    } else {
+        /* Nothing to do */
+    }
+}
+
+static uint32_t prep_port0092_read(void *opaque, uint32_t addr)
+{
+    PrepSystemIoState *s = opaque;
+    /* XXX LE mode unsupported */
+    trace_prep_systemio_read(addr, 0);
+    return s->sreset;
+}
+
+/* PORT 0808 -- Hardfile Light Register (Write Only) */
+
+enum {
+    PORT0808_HARDFILE_LIGHT_ON  = BIT(7),
+};
+
+static void prep_port0808_write(void *opaque, uint32_t addr, uint32_t val)
+{
+    trace_prep_systemio_write(addr, val);
+}
+
+/* PORT 0810 -- Password Protect 1 Register (Write Only) */
+
+/* reset by port 0x4D in the SIO */
+static void prep_port0810_write(void *opaque, uint32_t addr, uint32_t val)
+{
+    trace_prep_systemio_write(addr, val);
+}
+
+/* PORT 0812 -- Password Protect 2 Register (Write Only) */
+
+/* reset by port 0x4D in the SIO */
+static void prep_port0812_write(void *opaque, uint32_t addr, uint32_t val)
+{
+    trace_prep_systemio_write(addr, val);
+}
+
+/* PORT 0814 -- L2 Invalidate Register (Write Only) */
+
+static void prep_port0814_write(void *opaque, uint32_t addr, uint32_t val)
+{
+    trace_prep_systemio_write(addr, val);
+}
+
+/* PORT 0818 -- Reserved for Keylock (Read Only) */
+
+enum {
+    PORT0818_KEYLOCK_SIGNAL_HIGH    = BIT(7),
+};
+
+static uint32_t prep_port0818_read(void *opaque, uint32_t addr)
+{
+    uint32_t val = 0;
+    trace_prep_systemio_read(addr, val);
+    return val;
+}
+
+/* PORT 080C -- Equipment */
+
+enum {
+    PORT080C_SCSIFUSE               = BIT(1),
+    PORT080C_L2_COPYBACK            = BIT(4),
+    PORT080C_L2_256                 = BIT(5),
+    PORT080C_UPGRADE_CPU            = BIT(6),
+    PORT080C_L2                     = BIT(7),
+};
+
+static uint32_t prep_port080c_read(void *opaque, uint32_t addr)
+{
+    PrepSystemIoState *s = opaque;
+    trace_prep_systemio_read(addr, s->equipment);
+    return s->equipment;
+}
+
+/* PORT 081C -- System Control Register (Read/Write) */
+
+enum {
+    PORT081C_FLOPPY_MOTOR_INHIBIT   = BIT(3),
+    PORT081C_MASK_TEA               = BIT(2),
+    PORT081C_L2_UPDATE_INHIBIT      = BIT(1),
+    PORT081C_L2_CACHEMISS_INHIBIT   = BIT(0),
+};
+
+static void prep_port081c_write(void *opaque, uint32_t addr, uint32_t val)
+{
+    PrepSystemIoState *s = opaque;
+    trace_prep_systemio_write(addr, val);
+    s->system_control = val;
+}
+
+static uint32_t prep_port081c_read(void *opaque, uint32_t addr)
+{
+    PrepSystemIoState *s = opaque;
+    trace_prep_systemio_read(addr, s->system_control);
+    return s->system_control;
+}
+
+/* System Board Identification */
+
+static uint32_t prep_port0852_read(void *opaque, uint32_t addr)
+{
+    PrepSystemIoState *s = opaque;
+    trace_prep_systemio_read(addr, s->ibm_planar_id);
+    return s->ibm_planar_id;
+}
+
+/* PORT 0850 -- I/O Map Type Register (Read/Write) */
+
+enum {
+    PORT0850_IOMAP_NONCONTIGUOUS    = BIT(7),
+};
+
+static uint32_t prep_port0850_read(void *opaque, uint32_t addr)
+{
+    PrepSystemIoState *s = opaque;
+    trace_prep_systemio_read(addr, s->iomap_type);
+    return s->iomap_type;
+}
+
+static void prep_port0850_write(void *opaque, uint32_t addr, uint32_t val)
+{
+    PrepSystemIoState *s = opaque;
+
+    trace_prep_systemio_write(addr, val);
+    qemu_set_irq(s->non_contiguous_io_map_irq,
+                 val & PORT0850_IOMAP_NONCONTIGUOUS ? 1 : 0);
+    s->iomap_type = val;
+}
+
+static const MemoryRegionPortio ppc_io800_port_list[] = {
+    { 0x092, 1, 1, .read = prep_port0092_read,
+                   .write = prep_port0092_write, },
+    { 0x808, 1, 1, .write = prep_port0808_write, },
+    { 0x80c, 1, 1, .read = prep_port080c_read, },
+    { 0x810, 1, 1, .write = prep_port0810_write, },
+    { 0x812, 1, 1, .write = prep_port0812_write, },
+    { 0x814, 1, 1, .write = prep_port0814_write, },
+    { 0x818, 1, 1, .read = prep_port0818_read, },
+    { 0x81c, 1, 1, .read = prep_port081c_read,
+                   .write = prep_port081c_write, },
+    { 0x850, 1, 1, .read = prep_port0850_read,
+                   .write = prep_port0850_write, },
+    { 0x852, 1, 1, .read = prep_port0852_read, },
+    PORTIO_END_OF_LIST()
+};
+
+static uint64_t ppc_parity_error_readl(void *opaque, hwaddr addr,
+                                       unsigned int size)
+{
+    uint32_t val = 0;
+    trace_prep_systemio_read((unsigned int)addr, val);
+    return val;
+}
+
+static const MemoryRegionOps ppc_parity_error_ops = {
+    .read = ppc_parity_error_readl,
+    .valid = {
+        .min_access_size = 4,
+        .max_access_size = 4,
+    },
+};
+
+static int prep_systemio_init(ISADevice *dev)
+{
+    PrepSystemIoState *s = PREP_SYSTEMIO(dev);
+    qdev_init_gpio_out(&dev->qdev, &s->non_contiguous_io_map_irq, 1);
+    s->iomap_type = 0; /* contiguous mode XXX 0x1? */
+    s->softreset_irq = first_cpu->irq_inputs[PPC6xx_INPUT_HRESET];
+
+    isa_register_portio_list(dev, 0x0, ppc_io800_port_list, s, "systemio800");
+
+    memory_region_init_io(&s->ppc_parity_mem, &ppc_parity_error_ops, s,
+                          "ppc-parity", 0x4);
+    memory_region_add_subregion(get_system_memory(), 0xbfffeff0,
+                                &s->ppc_parity_mem);
+    return 0;
+}
+
+static const VMStateDescription vmstate_prep_systemio = {
+    .name = "prep_systemio",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .fields = (VMStateField[]) {
+        VMSTATE_UINT8(system_control, PrepSystemIoState),
+        VMSTATE_UINT8(iomap_type, PrepSystemIoState),
+        VMSTATE_END_OF_LIST()
+    },
+};
+
+static Property prep_systemio_properties[] = {
+    DEFINE_PROP_UINT8("ibm-planar-id", PrepSystemIoState, ibm_planar_id, 0),
+    DEFINE_PROP_UINT8("equipment", PrepSystemIoState, equipment, 0),
+    DEFINE_PROP_END_OF_LIST()
+};
+
+static void prep_systemio_class_initfn(ObjectClass *klass, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+    ISADeviceClass *ic = ISA_DEVICE_CLASS(klass);
+    ic->init = prep_systemio_init;
+    dc->vmsd = &vmstate_prep_systemio;
+    dc->props = prep_systemio_properties;
+    dc->no_user = 1;
+}
+
+static TypeInfo prep_systemio800_info = {
+    .name          = TYPE_PREP_SYSTEMIO,
+    .parent        = TYPE_ISA_DEVICE,
+    .instance_size = sizeof(PrepSystemIoState),
+    .class_init    = prep_systemio_class_initfn,
+};
+
+static void prep_systemio_register_types(void)
+{
+    type_register_static(&prep_systemio800_info);
+}
+
+type_init(prep_systemio_register_types)
diff --git a/trace-events b/trace-events
index 1970b5c..be35eed 100644
--- a/trace-events
+++ b/trace-events
@@ -773,6 +773,10 @@ mpc105_simm_enable(int id, uint32_t start, uint32_t end) "SIMM #%d 0x%08x-0x%08x
 mpc105_simm_disable(int id) "SIMM #%d disabled"
 mpc105_simm_size(int id, uint32_t size) "SIMM #%d is %u MB"
 
+# hw/ppc/prep_systemio.c
+prep_systemio_read(uint32_t addr, uint32_t val) "read addr=%x val=%x"
+prep_systemio_write(uint32_t addr, uint32_t val) "write addr=%x val=%x"
+
 # hw/scsi/vmw_pvscsi.c
 pvscsi_ring_init_data(uint32_t txr_len_log2, uint32_t rxr_len_log2) "TX/RX rings logarithms set to %d/%d"
 pvscsi_ring_init_msg(uint32_t len_log2) "MSG ring logarithm set to %d"
