diff --git a/src/cdrom/cdrom.c b/src/cdrom/cdrom.c
index 65743bead..5a50c0cd7 100644
--- a/src/cdrom/cdrom.c
+++ b/src/cdrom/cdrom.c
@@ -9,7 +9,7 @@
  *		Implementation of the CD-ROM drive with SCSI(-like)
  *		commands, for both ATAPI and SCSI usage.
  *
- * Version:	@(#)cdrom.c	1.0.33	2018/02/27
+ * Version:	@(#)cdrom.c	1.0.34	2018/03/06
  *
  * Author:	Miran Grca, <mgrca8@gmail.com>
  *
@@ -715,25 +715,53 @@ void cdrom_update_request_length(uint8_t id, int len, int block_len)
 
 static void cdrom_command_common(uint8_t id)
 {
+	double bytes_per_second, period;
+	double dusec;
+
 	cdrom[id].status = BUSY_STAT;
 	cdrom[id].phase = 1;
 	cdrom[id].pos = 0;
 	if (cdrom[id].packet_status == CDROM_PHASE_COMPLETE) {
-		cdrom[id].callback = 20LL * CDROM_TIME;
-		cdrom_set_callback(id);
-	} else if (cdrom[id].packet_status == CDROM_PHASE_DATA_IN) {
-		if (cdrom[id].current_cdb[0] == 0x42) {
-			cdrom_log("CD-ROM %i: READ SUBCHANNEL\n", id);
-			cdrom[id].callback = 1000LL * CDROM_TIME;
-			cdrom_set_callback(id);
-		} else {
-			cdrom[id].callback = 60LL * CDROM_TIME;
-			cdrom_set_callback(id);
-		}
+		cdrom_phase_callback(id);
+		cdrom[id].callback = 0LL;
 	} else {
-		cdrom[id].callback = 60LL * CDROM_TIME;
-		cdrom_set_callback(id);
+		switch(cdrom[id].current_cdb[0]) {
+			case 0x25:
+			case 0x42:
+			case 0x43:
+			case 0x44:
+			case 0x08:
+			case 0x28:
+			case 0x51:
+			case 0x52:
+			case 0xa8:
+			case 0xad:
+			case 0xb8:
+			case 0xb9:
+			case 0xbe:
+				bytes_per_second = 150.0 * 1024.0;
+				bytes_per_second *= (double) cdrom_drives[id].speed;
+				break;
+			default:
+				if (cdrom_drives[id].bus_type == CDROM_BUS_SCSI) {
+					cdrom[id].callback = -1LL;	/* Speed depends on SCSI controller */
+					return;
+				} else if (cdrom_drives[id].bus_type == CDROM_BUS_ATAPI_PIO_AND_DMA) {
+					if (cdrom_current_mode(id) == 2)
+						bytes_per_second = 66666666.666666666666666;	/* 66 MB/s MDMA-2 speed */
+					else
+						bytes_per_second =  8333333.333333333333333;	/* 8.3 MB/s PIO-2 speed */
+				} else
+					bytes_per_second = 3333333.333333333333333;		/* 3.3 MB/s PIO-0 speed */
+				break;
+		}
+
+		period = 1000000.0 / bytes_per_second;
+		dusec = (double) TIMER_USEC;
+		dusec = dusec * period * (double) (cdrom[id].packet_len);
+		cdrom[id].callback = ((int64_t) dusec);
 	}
+	cdrom_set_callback(id);
 }
 
 static void cdrom_command_complete(uint8_t id)
diff --git a/src/cdrom/cdrom.h b/src/cdrom/cdrom.h
index bf208267f..d82a002cb 100644
--- a/src/cdrom/cdrom.h
+++ b/src/cdrom/cdrom.h
@@ -9,7 +9,7 @@
  *		Implementation of the CD-ROM drive with SCSI(-like)
  *		commands, for both ATAPI and SCSI usage.
  *
- * Version:	@(#)cdrom.h	1.0.4	2017/11/01
+ * Version:	@(#)cdrom.h	1.0.5	2018/03/06
  *
  * Author:	Miran Grca, <mgrca8@gmail.com>
  *
@@ -169,6 +169,8 @@ typedef struct {
 	
 	unsigned int sound_on;
 	unsigned int atapi_dma;
+
+	uint8_t speed;
 } cdrom_drive_t;
 
 typedef struct {
diff --git a/src/config.c b/src/config.c
index dd709f765..86e002153 100644
--- a/src/config.c
+++ b/src/config.c
@@ -8,7 +8,7 @@
  *
  *		Configuration file handler.
  *
- * Version:	@(#)config.c	1.0.43	2018/03/06
+ * Version:	@(#)config.c	1.0.44	2018/03/06
  *
  * Authors:	Sarah Walker,
  *		Miran Grca, <mgrca8@gmail.com>
@@ -1225,6 +1225,9 @@ load_other_removable_devices(void)
 		sscanf("0, none", "%01u, %s", &cdrom_drives[c].sound_on, s);
 	cdrom_drives[c].bus_type = hdd_string_to_bus(s, 1);
 
+	sprintf(temp, "cdrom_%02i_speed", c+1);
+	cdrom_drives[c].speed = config_get_int(cat, temp, 8);
+
 	/* Default values, needed for proper operation of the Settings dialog. */
 	cdrom_drives[c].ide_channel = cdrom_drives[c].scsi_device_id = c + 2;
 
@@ -1980,6 +1983,13 @@ save_other_removable_devices(void)
 		config_set_int(cat, temp, cdrom_drives[c].host_drive);
 	}
 
+	sprintf(temp, "cdrom_%02i_speed", c+1);
+	if ((cdrom_drives[c].bus_type == 0) || (cdrom_drives[c].speed == 8)) {
+		config_delete_var(cat, temp);
+	} else {
+		config_set_int(cat, temp, cdrom_drives[c].speed);
+	}
+
 	sprintf(temp, "cdrom_%02i_parameters", c+1);
 	if (cdrom_drives[c].bus_type == 0) {
 		config_delete_var(cat, temp);
diff --git a/src/disk/zip.c b/src/disk/zip.c
index 40eaa9de8..cd20e2253 100644
--- a/src/disk/zip.c
+++ b/src/disk/zip.c
@@ -9,7 +9,7 @@
  *		Implementation of the Iomega ZIP drive with SCSI(-like)
  *		commands, for both ATAPI and SCSI usage.
  *
- * Version:	@(#)zip.c	1.0.7	2018/03/06
+ * Version:	@(#)zip.c	1.0.8	2018/03/07
  *
  * Author:	Miran Grca, <mgrca8@gmail.com>
  *
@@ -932,25 +932,34 @@ void zip_update_request_length(uint8_t id, int len, int block_len)
 
 static void zip_command_common(uint8_t id)
 {
+	double bytes_per_second, period;
+	double dusec;
+
 	zip[id].status = BUSY_STAT;
 	zip[id].phase = 1;
 	zip[id].pos = 0;
 	if (zip[id].packet_status == ZIP_PHASE_COMPLETE) {
-		zip[id].callback = 20LL * ZIP_TIME;
-		zip_set_callback(id);
-	} else if (zip[id].packet_status == ZIP_PHASE_DATA_IN) {
-		if (zip[id].current_cdb[0] == 0x42) {
-			zip_log("ZIP %i: READ SUBCHANNEL\n");
-			zip[id].callback = 1000LL * ZIP_TIME;
-			zip_set_callback(id);
-		} else {
-			zip[id].callback = 60LL * ZIP_TIME;
-			zip_set_callback(id);
-		}
+		zip_phase_callback(id);
+		zip[id].callback = 0LL;
 	} else {
-		zip[id].callback = 60LL * ZIP_TIME;
-		zip_set_callback(id);
+		if (zip_drives[id].bus_type == ZIP_BUS_SCSI) {
+			zip[id].callback = -1LL;	/* Speed depends on SCSI controller */
+			return;
+		} else if (zip_drives[id].bus_type == ZIP_BUS_ATAPI_PIO_AND_DMA) {
+			if (zip_current_mode(id) == 2)
+				bytes_per_second = 66666666.666666666666666;	/* 66 MB/s MDMA-2 speed */
+			else
+				bytes_per_second =  8333333.333333333333333;	/* 8.3 MB/s PIO-2 speed */
+		} else
+			bytes_per_second = 3333333.333333333333333;		/* 3.3 MB/s PIO-0 speed */
 	}
+
+	period = 1000000.0 / bytes_per_second;
+	dusec = (double) TIMER_USEC;
+	dusec = dusec * period * (double) (zip[id].packet_len);
+	zip[id].callback = ((int64_t) dusec);
+
+	zip_set_callback(id);
 }
 
 static void zip_command_complete(uint8_t id)
diff --git a/src/lang/language.h b/src/lang/language.h
index 92f7f4df9..e4c060da8 100644
--- a/src/lang/language.h
+++ b/src/lang/language.h
@@ -10,7 +10,7 @@
  *
  * NOTE:	FIXME: Strings 2176 and 2193 are same.
  *
- * Version:	@(#)language.h	1.0.6	2018/01/23
+ * Version:	@(#)language.h	1.0.7	2018/03/07
  *
  * Author:	Fred N. van Kempen, <decwiz@yahoo.com>
  *
@@ -151,6 +151,7 @@
 #define IDS_2175	2175		// "ZIP images (*.IM?)\0*.IM..."
 #define IDS_2176	2176		// "ZIP images (*.IM?)\0*.IM..."
 #define IDS_2177	2177		// "ZIP %i (%03i): %ls"
+#define IDS_2178	2178		// "Speed"
 
 #define IDS_4096	4096		// "Hard disk (%s)"
 #define IDS_4097	4097		// "%01i:%01i"
@@ -231,7 +232,7 @@
 
 #define IDS_LANG_ENUS	IDS_7168
 
-#define STR_NUM_2048	130
+#define STR_NUM_2048	131
 #define STR_NUM_3072	11
 #define STR_NUM_4096	20
 #define STR_NUM_4352	7
diff --git a/src/scsi/scsi_aha154x.c b/src/scsi/scsi_aha154x.c
index 67aefc15d..efc9a5fcb 100644
--- a/src/scsi/scsi_aha154x.c
+++ b/src/scsi/scsi_aha154x.c
@@ -10,7 +10,7 @@
  *		made by Adaptec, Inc. These controllers were designed for
  *		the ISA bus.
  *
- * Version:	@(#)scsi_aha154x.c	1.0.38	2018/02/19
+ * Version:	@(#)scsi_aha154x.c	1.0.39	2018/03/07
  *
  * Authors:	Fred N. van Kempen, <decwiz@yahoo.com>
  *		Original Buslogic version by SA1988 and Miran Grca.
@@ -267,10 +267,7 @@ aha_fast_cmds(void *p, uint8_t cmd)
     x54x_t *dev = (x54x_t *)p;
 
     if (cmd == CMD_BIOS_SCSI) {
-	x54x_busy(1);
 	dev->BIOSMailboxReq++;
-	x54x_set_wait_event();
-	x54x_busy(0);
 	return 1;
     }
 
@@ -362,7 +359,6 @@ aha_cmds(void *p)
 
 		case CMD_BIOS_MBINIT: /* BIOS Mailbox Initialization */
 			/* Sent by CF BIOS. */
-			x54x_busy(1);
 			dev->Mbx24bit = 1;
 
 			mbi = (MailboxInit_t *)dev->CmdBuf;
@@ -378,7 +374,6 @@ aha_cmds(void *p)
 
 			dev->Status &= ~STAT_INIT;
 			dev->DataReplyLeft = 0;
-			x54x_busy(0);
 			break;
 
 		case CMD_MEMORY_MAP_1:	/* AHA memory mapper */
@@ -467,16 +462,12 @@ aha_do_bios_mail(x54x_t *dev)
 
 
 static void
-aha_thread(void *p)
+aha_callback(void *p)
 {
     x54x_t *dev = (x54x_t *)p;
 
     if (dev->BIOSMailboxInit && dev->BIOSMailboxReq)
-    {
-	x54x_wait_for_poll();
-
 	aha_do_bios_mail(dev);
-    }
 }
 
 
@@ -768,7 +759,7 @@ aha_init(device_t *info)
     dev->bit32 = 0;
     dev->lba_bios = 0;
 
-    dev->ven_thread = aha_thread;
+    dev->ven_callback = aha_callback;
     dev->ven_cmd_is_fast = aha_cmd_is_fast;
     dev->ven_fast_cmds = aha_fast_cmds;
     dev->get_ven_param_len = aha_param_len;
@@ -797,6 +788,7 @@ aha_init(device_t *info)
 		dev->HostID = device_get_config_int("hostid");
 		dev->rom_shram = 0x3F80;	/* shadow RAM address base */
 		dev->rom_shramsz = 128;		/* size of shadow RAM */
+		dev->ha_bps = 5000000.0;	/* normal SCSI */
 		break;
 
 	case AHA_154xC:
@@ -811,6 +803,7 @@ aha_init(device_t *info)
 		dev->ven_get_host_id = aha_get_host_id;	/* function to return host ID from EEPROM */
 		dev->ven_get_irq = aha_get_irq;		/* function to return IRQ from EEPROM */
 		dev->ven_get_dma = aha_get_dma;		/* function to return DMA channel from EEPROM */
+		dev->ha_bps = 5000000.0;	/* normal SCSI */
 		break;
 
 	case AHA_154xCF:
@@ -826,6 +819,7 @@ aha_init(device_t *info)
 		dev->ven_get_host_id = aha_get_host_id;	/* function to return host ID from EEPROM */
 		dev->ven_get_irq = aha_get_irq;		/* function to return IRQ from EEPROM */
 		dev->ven_get_dma = aha_get_dma;		/* function to return DMA channel from EEPROM */
+		dev->ha_bps = 10000000.0;	/* fast SCSI */
 		break;
 
 	case AHA_154xCP:
@@ -840,6 +834,7 @@ aha_init(device_t *info)
 		dev->ven_get_host_id = aha_get_host_id;	/* function to return host ID from EEPROM */
 		dev->ven_get_irq = aha_get_irq;		/* function to return IRQ from EEPROM */
 		dev->ven_get_dma = aha_get_dma;		/* function to return DMA channel from EEPROM */
+		dev->ha_bps = 10000000.0;	/* fast SCSI */
 		break;
 
 	case AHA_1640:
@@ -853,6 +848,7 @@ aha_init(device_t *info)
 		dev->pos_regs[0] = 0x1F;	/* MCA board ID */
 		dev->pos_regs[1] = 0x0F;	
 		mca_add(aha_mca_read, aha_mca_write, dev);
+		dev->ha_bps = 5000000.0;	/* normal SCSI */
 		break;
     }	
 
diff --git a/src/scsi/scsi_buslogic.c b/src/scsi/scsi_buslogic.c
index 8e99c81f9..cd95e823b 100644
--- a/src/scsi/scsi_buslogic.c
+++ b/src/scsi/scsi_buslogic.c
@@ -11,14 +11,14 @@
  *		  1 - BT-545S ISA;
  *		  2 - BT-958D PCI
  *
- * Version:	@(#)scsi_buslogic.c	1.0.34	2018/01/06
+ * Version:	@(#)scsi_buslogic.c	1.0.35	2018/03/07
  *
  * Authors:	TheCollector1995, <mariogplayer@gmail.com>
  *		Miran Grca, <mgrca8@gmail.com>
  *		Fred N. van Kempen, <decwiz@yahoo.com>
  *
- *		Copyright 2016,2018 Miran Grca.
- *		Copyright 2018 Fred N. van Kempen.
+ *		Copyright 2016-2018 Miran Grca.
+ *		Copyright 2017,2018 Fred N. van Kempen.
  */
 #include <stdio.h>
 #include <stdint.h>
@@ -719,7 +719,6 @@ buslogic_cmds(void *p)
 			dev->IrqEnabled = 1;
 		return 1;
 	case 0x81:
-		x54x_busy(1);
 		dev->Mbx24bit = 0;
 
 		MailboxInitE = (MailboxInitExtended_t *)dev->CmdBuf;
@@ -736,7 +735,6 @@ buslogic_cmds(void *p)
 
 		dev->Status &= ~STAT_INIT;
 		dev->DataReplyLeft = 0;
-		x54x_busy(0);
 		break;
 	case 0x83:
 		if (dev->CmdParam == 12) {
@@ -1528,6 +1526,7 @@ buslogic_init(device_t *info)
 		has_autoscsi_rom = 0;
 		has_scam_rom = 0;
 		dev->fw_rev = "AA335";
+		dev->ha_bps = 5000000.0;	/* normal SCSI */
 		break;
 	case CHIP_BUSLOGIC_ISA:
 	default:
@@ -1540,6 +1539,7 @@ buslogic_init(device_t *info)
 		autoscsi_rom_size = 0x4000;
 		has_scam_rom = 0;
 		dev->fw_rev = "AA421E";
+		dev->ha_bps = 10000000.0;	/* fast SCSI */
 		break;
 	case CHIP_BUSLOGIC_MCA:
 		strcpy(dev->name, "BT-640A");
@@ -1553,6 +1553,7 @@ buslogic_init(device_t *info)
 		dev->pos_regs[0] = 0x08;	/* MCA board ID */
 		dev->pos_regs[1] = 0x07;	
 		mca_add(buslogic_mca_read, buslogic_mca_write, dev);
+		dev->ha_bps = 5000000.0;	/* normal SCSI */
 		break;
 	case CHIP_BUSLOGIC_VLB:
 		strcpy(dev->name, "BT-445S");
@@ -1565,6 +1566,7 @@ buslogic_init(device_t *info)
 		has_scam_rom = 0;
 		dev->fw_rev = "AA421E";
 		dev->bit32 = 1;
+		dev->ha_bps = 10000000.0;	/* fast SCSI */
 		break;
 	case CHIP_BUSLOGIC_PCI:
 		strcpy(dev->name, "BT-958D");
@@ -1580,6 +1582,7 @@ buslogic_init(device_t *info)
 		dev->fw_rev = "AA507B";
 		dev->cdrom_boot = 1;
 		dev->bit32 = 1;
+		dev->ha_bps = 20000000.0;	/* ultra SCSI */
 		break;
     }
 
diff --git a/src/scsi/scsi_device.c b/src/scsi/scsi_device.c
index 646189628..91350ec3d 100644
--- a/src/scsi/scsi_device.c
+++ b/src/scsi/scsi_device.c
@@ -8,7 +8,7 @@
  *
  *		The generic SCSI device command handler.
  *
- * Version:	@(#)scsi_device.c	1.0.13	2018/03/06
+ * Version:	@(#)scsi_device.c	1.0.14	2018/03/07
  *
  * Authors:	Miran Grca, <mgrca8@gmail.com>
  *		Fred N. van Kempen, <decwiz@yahoo.com>
@@ -119,6 +119,33 @@ static void scsi_device_target_save_cdb_byte(int lun_type, uint8_t id, uint8_t c
 }
 
 
+int64_t scsi_device_get_callback(uint8_t scsi_id, uint8_t scsi_lun)
+{
+    uint8_t lun_type = SCSIDevices[scsi_id][scsi_lun].LunType;
+
+    uint8_t id = 0;
+
+    switch (lun_type)
+    {
+	case SCSI_DISK:
+		id = scsi_hard_disks[scsi_id][scsi_lun];
+		return shdc[id].callback;
+		break;
+	case SCSI_CDROM:
+		id = scsi_cdrom_drives[scsi_id][scsi_lun];
+		return cdrom[id].callback;
+		break;
+	case SCSI_ZIP:
+		id = scsi_zip_drives[scsi_id][scsi_lun];
+		return zip[id].callback;
+		break;
+	default:
+		return -1LL;
+		break;
+    }
+}
+
+
 uint8_t *scsi_device_sense(uint8_t scsi_id, uint8_t scsi_lun)
 {
     uint8_t lun_type = SCSIDevices[scsi_id][scsi_lun].LunType;
diff --git a/src/scsi/scsi_device.h b/src/scsi/scsi_device.h
index f89fac3bd..9d7267528 100644
--- a/src/scsi/scsi_device.h
+++ b/src/scsi/scsi_device.h
@@ -8,7 +8,7 @@
  *
  *		Definitions for the generic SCSI device command handler.
  *
- * Version:	@(#)scsi_device.h	1.0.5	2018/02/17
+ * Version:	@(#)scsi_device.h	1.0.6	2018/03/07
  *
  * Authors:	Miran Grca, <mgrca8@gmail.com>
  *		Fred N. van Kempen, <decwiz@yahoo.com>
@@ -35,6 +35,7 @@ typedef struct
 extern uint8_t	*scsi_device_sense(uint8_t id, uint8_t lun);
 extern void	scsi_device_type_data(uint8_t id, uint8_t lun,
 				      uint8_t *type, uint8_t *rmb);
+extern int64_t	scsi_device_get_callback(uint8_t scsi_id, uint8_t scsi_lun);
 extern void	scsi_device_request_sense(uint8_t scsi_id, uint8_t scsi_lun,
 					  uint8_t *buffer,
 					  uint8_t alloc_length);
diff --git a/src/scsi/scsi_disk.c b/src/scsi/scsi_disk.c
index 0e346c255..c5c374935 100644
--- a/src/scsi/scsi_disk.c
+++ b/src/scsi/scsi_disk.c
@@ -6,11 +6,11 @@
  *
  *		Emulation of SCSI fixed and removable disks.
  *
- * Version:	@(#)scsi_disk.c	1.0.16	2018/01/25
+ * Version:	@(#)scsi_disk.c	1.0.17	2018/03/07
  *
  * Author:	Miran Grca, <mgrca8@gmail.com>
  *
- *		Copyright 2018 Miran Grca.
+ *		Copyright 2017,2018 Miran Grca.
  */
 #include <stdio.h>
 #include <stdint.h>
@@ -459,14 +459,11 @@ static void scsi_hd_command_common(uint8_t id)
 	shdc[id].status = BUSY_STAT;
 	shdc[id].phase = 1;
 	shdc[id].pos = 0;
-	if (shdc[id].packet_status == CDROM_PHASE_COMPLETE)
-	{
-		shdc[id].callback = 20 * SCSI_TIME;
-	}
-	else
-	{
-		shdc[id].callback = 60 * SCSI_TIME;
-	}
+	if (shdc[id].packet_status == CDROM_PHASE_COMPLETE) {
+		scsi_hd_callback(id);
+		shdc[id].callback = 0LL;
+	} else
+		shdc[id].callback = -1LL;	/* Speed depends on SCSI controller */
 }
 
 
diff --git a/src/scsi/scsi_ncr5380.c b/src/scsi/scsi_ncr5380.c
index 2614d0ff6..97440394f 100644
--- a/src/scsi/scsi_ncr5380.c
+++ b/src/scsi/scsi_ncr5380.c
@@ -9,15 +9,15 @@
  *		Implementation of the NCR 5380 series of SCSI Host Adapters
  *		made by NCR. These controllers were designed for the ISA bus.
  *
- * Version:	@(#)scsi_ncr5380.c	1.0.10	2018/01/26
+ * Version:	@(#)scsi_ncr5380.c	1.0.11	2018/03/07
  *
  * Authors:	Sarah Walker, <http://pcem-emulator.co.uk/>
  *		TheCollector1995, <mariogplayer@gmail.com>
  *		Fred N. van Kempen, <decwiz@yahoo.com>
  *
- *		Copyright 2017-2018 Sarah Walker.
- *		Copyright 2017-2018 TheCollector1995.
- *		Copyright 2018 Fred N. van Kempen.
+ *		Copyright 2017,2018 Sarah Walker.
+ *		Copyright 2017,2018 TheCollector1995.
+ *		Copyright 2017,2018 Fred N. van Kempen.
  */
 #include <stdio.h>
 #include <stdint.h>
@@ -390,7 +390,7 @@ dma_callback(void *priv)
     int bytes_transferred = 0;
     int c;
 
-    scsi->dma_timer += POLL_TIME_US;
+    scsi->dma_timer += POLL_TIME_US * TIMER_USEC;
 
     switch (scsi->ncr.dma_mode) {
 	case DMA_SEND:
diff --git a/src/scsi/scsi_ncr53c810.c b/src/scsi/scsi_ncr53c810.c
index bc970282d..b7b7b2b32 100644
--- a/src/scsi/scsi_ncr53c810.c
+++ b/src/scsi/scsi_ncr53c810.c
@@ -10,7 +10,7 @@
  *		NCR and later Symbios and LSI. This controller was designed
  *		for the PCI bus.
  *
- * Version:	@(#)scsi_ncr53c810.c	1.0.6	2018/01/06
+ * Version:	@(#)scsi_ncr53c810.c	1.0.7	2018/03/07
  *
  * Authors:	Paul Brook (QEMU)
  *		Artyom Tarasenko (QEMU)
@@ -19,8 +19,9 @@
  *
  *		Copyright 2006-2018 Paul Brook.
  *		Copyright 2009-2018 Artyom Tarasenko.
- *		Copyright 2018 Miran Grca.
+ *		Copyright 2017,2018 Miran Grca.
  */
+#include <inttypes.h>
 #include <stdio.h>
 #include <stdint.h>
 #include <string.h>
@@ -268,6 +269,9 @@ typedef struct {
 
     uint8_t regop;
     uint32_t adder;
+
+    int64_t timer_period;
+    int64_t timer_enabled;
 } ncr53c810_t;
 
 
@@ -326,6 +330,8 @@ static void
 ncr53c810_soft_reset(ncr53c810_t *dev)
 {
     ncr53c810_log("LSI Reset\n");
+    dev->timer_period = dev->timer_enabled = 0;
+
     dev->carry = 0;
 
     dev->msg_action = 0;
@@ -496,6 +502,7 @@ ncr53c810_script_scsi_interrupt(ncr53c810_t *dev, int stat0, int stat1)
     if ((dev->sist0 & mask0) || (dev->sist1 & mask1)) {
 	ncr53c810_log("NCR 810: IRQ-mandated stop\n");
 	dev->sstop = 1;
+	dev->timer_period = dev->timer_enabled = 0;
     }
     ncr53c810_update_irq(dev);
 }
@@ -509,6 +516,7 @@ ncr53c810_script_dma_interrupt(ncr53c810_t *dev, int stat)
     dev->dstat |= stat;
     ncr53c810_update_irq(dev);
     dev->sstop = 1;
+    dev->timer_period = dev->timer_enabled = 0;
 }
 
 
@@ -526,6 +534,7 @@ ncr53c810_bad_phase(ncr53c810_t *dev, int out, int new_phase)
     ncr53c810_log("Phase mismatch interrupt\n");
     ncr53c810_script_scsi_interrupt(dev, NCR_SIST0_MA, 0);
     dev->sstop = 1;
+    dev->timer_period = dev->timer_enabled = 0;
     ncr53c810_set_phase(dev, new_phase);
 }
 
@@ -650,6 +659,8 @@ ncr53c810_do_command(ncr53c810_t *dev, uint8_t id)
     scsi_device_t *sd;
     uint8_t buf[12];
 
+    double period;
+
     memset(buf, 0, 12);
     DMAPageRead(dev->dnad, buf, MIN(12, dev->dbc));
     if (dev->dbc > 12) {
@@ -690,9 +701,19 @@ ncr53c810_do_command(ncr53c810_t *dev, uint8_t id)
     if ((sd->Phase == SCSI_PHASE_DATA_IN) && (sd->BufferLength > 0)) {
 	ncr53c810_log("(ID=%02i LUN=%02i) SCSI Command 0x%02x: PHASE_DI\n", id, dev->current_lun, buf[0]);
 	ncr53c810_set_phase(dev, PHASE_DI);
+	dev->timer_period = scsi_device_get_callback(dev->current->tag, dev->current_lun);
+	if (dev->timer_period <= 0LL) {
+	        period = ((double) sd->BufferLength) * 0.2 * ((double) TIMER_USEC);	/* Fast SCSI: 10000000 bytes per second */
+		dev->timer_period = (int64_t) period;
+	}
     } else if ((sd->Phase == SCSI_PHASE_DATA_OUT) && (sd->BufferLength > 0)) {
 	ncr53c810_log("(ID=%02i LUN=%02i) SCSI Command 0x%02x: PHASE_DO\n", id, dev->current_lun, buf[0]);
 	ncr53c810_set_phase(dev, PHASE_DO);
+	dev->timer_period = scsi_device_get_callback(dev->current->tag, dev->current_lun);
+	if (dev->timer_period <= 0LL) {
+	        period = ((double) sd->BufferLength) * 0.2 * ((double) TIMER_USEC);	/* Fast SCSI: 10000000 bytes per second */
+		dev->timer_period = (int64_t) period;
+	}
     } else
 	ncr53c810_command_complete(dev, sd->Status);
 }
@@ -907,7 +928,7 @@ ncr53c810_memcpy(ncr53c810_t *dev, uint32_t dest, uint32_t src, int count)
 
 
 static void
-ncr53c810_execute_script(ncr53c810_t *dev)
+ncr53c810_process_script(ncr53c810_t *dev)
 {
     uint32_t insn, addr, id, buf[2], dest;
     int opcode, insn_processed = 0, reg, operator, cond, jmp, n, i;
@@ -936,6 +957,7 @@ again:
 		if (dev->sist1 & NCR_SIST1_STO) {
 		ncr53c810_log("Delayed select timeout\n");
 			dev->sstop = 1;
+			dev->timer_period = dev->timer_enabled = 0;
 			break;
 		}
 		ncr53c810_log("Block Move DBC=%d\n", dev->dbc);
@@ -981,7 +1003,9 @@ again:
 			case PHASE_CMD:
 				ncr53c810_log("Command Phase\n");
 				ncr53c810_do_command(dev, dev->sdid);
-				break;
+				dev->dfifo = dev->dbc & 0xff;
+				dev->ctest5 = (dev->ctest5 & 0xfc) | ((dev->dbc >> 8) & 3);
+				return;
 			case PHASE_ST:
 				ncr53c810_log("Status Phase\n");
 				ncr53c810_do_status(dev);
@@ -1153,6 +1177,7 @@ again:
 		if (dev->sist1 & NCR_SIST1_STO) {
 			ncr53c810_log("Delayed select timeout\n");
 			dev->sstop = 1;
+			dev->timer_period = dev->timer_enabled = 0;
 			break;
 		}
 		cond = jmp = (insn & (1 << 19)) != 0;
@@ -1262,7 +1287,8 @@ again:
 		ncr53c810_script_dma_interrupt(dev, NCR_DSTAT_SSI);
 	} else {
 		ncr53c810_log("NCR 810: SCRIPTS: Normal mode\n");
-		goto again;
+		if (insn_processed < 100)
+			goto again;
 	}
     } else {
 	if (dev->sstop)
@@ -1271,10 +1297,41 @@ again:
 		ncr53c810_log("NCR 810: SCRIPTS: Waiting\n");
     }
 
+    return;
+
     ncr53c810_log("SCRIPTS execution stopped\n");
 }
 
 
+static void
+ncr53c810_execute_script(ncr53c810_t *dev)
+{
+    dev->timer_period = 10LL * TIMER_USEC;
+    dev->timer_enabled = 1;
+}
+
+
+static void
+ncr53c810_callback(void *p)
+{
+    ncr53c810_t *dev = (ncr53c810_t *) p;
+
+    dev->timer_period = 0;
+    if (!dev->waiting)
+    	ncr53c810_process_script(dev);
+
+    if (dev->sstop) {
+	dev->timer_period = 0;
+	dev->timer_enabled = 0;
+	return;
+    } else
+	dev->timer_enabled = 1;
+
+    if (dev->timer_period == 0)
+	dev->timer_period = 50LL * TIMER_USEC;
+}
+
+
 static void
 ncr53c810_reg_writeb(ncr53c810_t *dev, uint32_t offset, uint8_t val)
 {
@@ -1377,7 +1434,7 @@ ncr53c810_reg_writeb(ncr53c810_t *dev, uint32_t offset, uint8_t val)
 			ncr53c810_log("Woken by SIGP\n");
 			dev->waiting = 0;
 			dev->dsp = dev->dnad;
-			ncr53c810_execute_script(dev);
+			/* ncr53c810_execute_script(dev); */
 		}
 		if ((val & NCR_ISTAT_SRST) && !(tmp & NCR_ISTAT_SRST)) {
 			ncr53c810_soft_reset(dev);
@@ -2076,6 +2133,8 @@ ncr53c810_init(device_t *info)
 
     ncr53c810_soft_reset(dev);
 
+    timer_add(ncr53c810_callback, &dev->timer_period, &dev->timer_enabled, dev);
+
     return(dev);
 }
 
diff --git a/src/scsi/scsi_x54x.c b/src/scsi/scsi_x54x.c
index 3b58a03cd..a234e6c3f 100644
--- a/src/scsi/scsi_x54x.c
+++ b/src/scsi/scsi_x54x.c
@@ -11,7 +11,7 @@
  *		series of SCSI Host Adapters made by Mylex.
  *		These controllers were designed for various buses.
  *
- * Version:	@(#)scsi_x54x.c	1.0.17	2018/02/25
+ * Version:	@(#)scsi_x54x.c	1.0.18	2018/03/07
  *
  * Authors:	TheCollector1995, <mariogplayer@gmail.com>
  *		Miran Grca, <mgrca8@gmail.com>
@@ -20,6 +20,7 @@
  *		Copyright 2016-2018 Miran Grca.
  *		Copyright 2017,2018 Fred N. van Kempen.
  */
+#include <inttypes.h>
 #include <stdio.h>
 #include <stdint.h>
 #include <string.h>
@@ -49,22 +50,7 @@
 #define X54X_RESET_DURATION_US	UINT64_C(50000)
 
 
-static void	x54x_cmd_thread(void *priv);
-
-static volatile
-thread_t	*poll_tid;
-static volatile
-int	busy;
-
-static volatile
-event_t	*evt;
-static volatile
-event_t	*wait_evt;
-
-static volatile
-event_t	*wake_poll_thread;
-static volatile
-event_t	*thread_started;
+static void	x54x_cmd_callback(void *priv);
 
 static volatile
 x54x_t	*x54x_dev;
@@ -609,6 +595,13 @@ x54x_cmd_done(x54x_t *dev, int suppress)
 }
 
 
+static void
+x54x_add_to_period(int TransferLength)
+{
+    x54x_dev->temp_period += (int64_t) TransferLength;
+}
+
+
 static void
 x54x_mbi_setup(x54x_t *dev, uint32_t CCBPointer, CCBU *CmdBlock,
 	       uint8_t HostStatus, uint8_t TargetStatus, uint8_t mbcc)
@@ -636,6 +629,7 @@ x54x_ccb(x54x_t *dev)
     DMAPageWrite(req->CCBPointer + 0x000D, &(req->MailboxCompletionCode), 1);
     DMAPageWrite(req->CCBPointer + 0x000E, &(req->HostStatus), 1);
     DMAPageWrite(req->CCBPointer + 0x000F, &(req->TargetStatus), 1);
+    x54x_add_to_period(3);
 
     if (dev->MailboxOutInterrupts)
 	dev->ToRaise = INTR_MBOA | INTR_ANY;
@@ -666,6 +660,7 @@ x54x_mbi(x54x_t *dev)
 	x54x_log("CCB statuses rewritten (pointer %08X)\n", req->CCBPointer);
     	DMAPageWrite(req->CCBPointer + 0x000E, &(req->HostStatus), 1);
 	DMAPageWrite(req->CCBPointer + 0x000F, &(req->TargetStatus), 1);
+	x54x_add_to_period(2);
     } else {
 	x54x_log("Mailbox not found!\n");
     }
@@ -677,6 +672,7 @@ x54x_mbi(x54x_t *dev)
 	x54x_log("Mailbox 24-bit: Status=0x%02X, CCB at 0x%04X\n", req->MailboxCompletionCode, CCBPointer);
 	DMAPageWrite(Incoming, &(req->MailboxCompletionCode), 1);
 	DMAPageWrite(Incoming + 1, (uint8_t *)&CCBPointer, 3);
+	x54x_add_to_period(4);
 	x54x_log("%i bytes of 24-bit mailbox written to: %08X\n", sizeof(Mailbox_t), Incoming);
     } else {
 	x54x_log("Mailbox 32-bit: Status=0x%02X, CCB at 0x%04X\n", req->MailboxCompletionCode, CCBPointer);
@@ -684,6 +680,7 @@ x54x_mbi(x54x_t *dev)
 	DMAPageWrite(Incoming + 4, &(req->HostStatus), 1);
 	DMAPageWrite(Incoming + 5, &(req->TargetStatus), 1);
 	DMAPageWrite(Incoming + 7, &(req->MailboxCompletionCode), 1);
+	x54x_add_to_period(7);
 	x54x_log("%i bytes of 32-bit mailbox written to: %08X\n", sizeof(Mailbox32_t), Incoming);
     }
 
@@ -704,6 +701,7 @@ x54x_rd_sge(int Is24bit, uint32_t Address, SGE32 *SG)
 
     if (Is24bit) {
 	DMAPageRead(Address, (uint8_t *)&SGE24, sizeof(SGE));
+	x54x_add_to_period(sizeof(SGE));
 
 	/* Convert the 24-bit entries into 32-bit entries. */
 	x54x_log("Read S/G block: %06X, %06X\n", SGE24.Segment, SGE24.SegmentPointer);
@@ -711,6 +709,7 @@ x54x_rd_sge(int Is24bit, uint32_t Address, SGE32 *SG)
 	SG->SegmentPointer = ADDR_TO_U32(SGE24.SegmentPointer);
     } else {
 	DMAPageRead(Address, (uint8_t *)SG, sizeof(SGE32));		
+	x54x_add_to_period(sizeof(SGE32));
     }
 }
 
@@ -778,9 +777,11 @@ x54x_set_residue(Req_t *req, int32_t TransferLength)
 	if (req->Is24bit) {
 		U32_TO_ADDR(Residue24, Residue);
     		DMAPageWrite(req->CCBPointer + 0x0004, (uint8_t *)&Residue24, 3);
+		x54x_add_to_period(3);
 		x54x_log("24-bit Residual data length for reading: %d\n", Residue);
 	} else {
     		DMAPageWrite(req->CCBPointer + 0x0004, (uint8_t *)&Residue, 4);
+		x54x_add_to_period(4);
 		x54x_log("32-bit Residual data length for reading: %d\n", Residue);
 	}
     }
@@ -832,9 +833,8 @@ x54x_buf_dma_transfer(Req_t *req, int Is24bit, int TransferLength, int dir)
 					x54x_log("Writing S/G segment %i: length %i, pointer %08X\n", i, DataToTransfer, Address);
 					DMAPageWrite(Address, &(SCSIDevices[req->TargetID][req->LUN].CmdBuffer[sg_pos]), DataToTransfer);
 				}
-				else {
+				else
 					x54x_log("No action on S/G segment %i: length %i, pointer %08X\n", i, DataToTransfer, Address);
-				}
 
 				sg_pos += SGBuffer.Segment;
 
@@ -850,11 +850,10 @@ x54x_buf_dma_transfer(Req_t *req, int Is24bit, int TransferLength, int dir)
 		Address = DataPointer;
 
 		if ((DataLength > 0) && (BufLen > 0) && (req->CmdBlock.common.ControlByte < 0x03)) {
-			if (read_from_host) {
+			if (read_from_host)
 				DMAPageRead(Address, SCSIDevices[req->TargetID][req->LUN].CmdBuffer, MIN(BufLen, DataLength));
-			} else if (write_to_host) {
+			else if (write_to_host)
 				DMAPageWrite(Address, SCSIDevices[req->TargetID][req->LUN].CmdBuffer, MIN(BufLen, DataLength));
-			}
 		}
 	}
     }
@@ -938,6 +937,7 @@ SenseBufferFree(Req_t *req, int Copy)
 	x54x_log("SenseBufferFree(): Writing %i bytes at %08X\n",
 					SenseLength, SenseBufferAddress);
 	DMAPageWrite(SenseBufferAddress, temp_sense, SenseLength);
+	x54x_add_to_period(SenseLength);
 	x54x_log("Sense data written to buffer: %02X %02X %02X\n",
 		temp_sense[2], temp_sense[12], temp_sense[13]);
     }
@@ -957,6 +957,7 @@ x54x_scsi_cmd(x54x_t *dev)
     int32_t *BufLen;
     uint8_t phase;
     uint32_t SenseBufferAddress;
+    int64_t p;
 
     id = req->TargetID;
     lun = req->LUN;
@@ -979,8 +980,10 @@ x54x_scsi_cmd(x54x_t *dev)
     if (req->CmdBlock.common.CdbLength <= target_cdb_len) {
 	memcpy(temp_cdb, req->CmdBlock.common.Cdb,
 	       req->CmdBlock.common.CdbLength);
+	x54x_add_to_period(req->CmdBlock.common.CdbLength);
     } else {
 	memcpy(temp_cdb, req->CmdBlock.common.Cdb, target_cdb_len);
+	x54x_add_to_period(target_cdb_len);
     }
 
     dev->Residue = 0;
@@ -1005,8 +1008,14 @@ x54x_scsi_cmd(x54x_t *dev)
 		if ((SCSIDevices[id][lun].Status != SCSI_STATUS_OK) && (*BufLen > 0)) {
 			SenseBufferAddress = SenseBufferPointer(req);
 			DMAPageWrite(SenseBufferAddress, SCSIDevices[id][lun].CmdBuffer, *BufLen);
+			x54x_add_to_period(*BufLen);
 		}
 	} else {
+		p = scsi_device_get_callback(id, lun);
+		if (p <= 0LL)
+			x54x_add_to_period(*BufLen);
+		else
+			dev->media_period += p;
 	    	x54x_buf_alloc(id, lun, MIN(target_data_len, *BufLen));
 		if (phase == SCSI_PHASE_DATA_OUT)
 			x54x_buf_dma_transfer(req, bit24, target_data_len, 1);
@@ -1034,10 +1043,6 @@ x54x_scsi_cmd(x54x_t *dev)
     }
 
     x54x_log("SCSIDevices[%02i][%02i].Status = %02X\n", id, lun, SCSIDevices[id][lun].Status);
-
-    if (temp_cdb[0] == 0x42) {
-	thread_wait_event((event_t *) evt, 10);
-    }
 }
 
 
@@ -1135,6 +1140,7 @@ x54x_req_abort(x54x_t *dev, uint32_t CCBPointer)
 
     /* Fetch data from the Command Control Block. */
     DMAPageRead(CCBPointer, (uint8_t *)&CmdBlock, sizeof(CCB32));
+    x54x_add_to_period(sizeof(CCB32));
 
     x54x_mbi_setup(dev, CCBPointer, &CmdBlock,
 		  0x26, SCSI_STATUS_OK, MBI_NOT_FOUND);
@@ -1163,6 +1169,7 @@ x54x_mbo(x54x_t *dev, Mailbox32_t *Mailbox32)
     if (dev->Mbx24bit) {
 	Outgoing = Addr + (Cur * sizeof(Mailbox_t));
 	DMAPageRead(Outgoing, (uint8_t *)&MailboxOut, sizeof(Mailbox_t));
+	x54x_add_to_period(sizeof(Mailbox_t));
 
 	ccbp = *(uint32_t *) &MailboxOut;
 	Mailbox32->CCBPointer = (ccbp >> 24) | ((ccbp >> 8) & 0xff00) | ((ccbp << 8) & 0xff0000);
@@ -1171,6 +1178,7 @@ x54x_mbo(x54x_t *dev, Mailbox32_t *Mailbox32)
 	Outgoing = Addr + (Cur * sizeof(Mailbox32_t));
 
 	DMAPageRead(Outgoing, (uint8_t *)Mailbox32, sizeof(Mailbox32_t));
+	x54x_add_to_period(sizeof(Mailbox32_t));
     }
 
     return(Outgoing);
@@ -1203,14 +1211,11 @@ x54x_mbo_process(x54x_t *dev)
 	/* We got the mailbox, mark it as free in the guest. */
 	x54x_log("x54x_do_mail(): Writing %i bytes at %08X\n", sizeof(CmdStatus), Outgoing + CodeOffset);
 	DMAPageWrite(Outgoing + CodeOffset, &CmdStatus, 1);
+	x54x_add_to_period(1);
 
-	if (dev->ToRaise) {
+	if (dev->ToRaise)
 		raise_irq(dev, 0, dev->ToRaise);
 
-		while (dev->Interrupt)
-			;
-	}
-
 	if (dev->MailboxIsBIOS)
 		dev->BIOSMailboxReq--;
 	  else
@@ -1264,84 +1269,29 @@ static void
 x54x_cmd_done(x54x_t *dev, int suppress);
 
 
-void
-x54x_wait_for_poll(void)
-{
-    if (x54x_is_busy()) {
-	thread_wait_event((event_t *) wake_poll_thread, -1);
-    }
-    thread_reset_event((event_t *) wake_poll_thread);
-}
-
-
 static void
-x54x_cmd_thread(void *priv)
+x54x_cmd_callback(void *priv)
 {
+    double period;
     x54x_t *dev = (x54x_t *) x54x_dev;
 
-    thread_set_event((event_t *) thread_started);
-
-    x54x_log("Polling thread started\n");
-
-    while (x54x_dev) {
-	scsi_mutex_wait(1);
-
-	if ((dev->Status & STAT_INIT) || (!dev->MailboxInit && !dev->BIOSMailboxInit) || (!dev->MailboxReq && !dev->BIOSMailboxReq)) {
-		/* If we did not get anything, wait a while. */
-		thread_wait_event((event_t *) wait_evt, 10);
-		thread_reset_event((event_t *) wait_evt);
-
-		scsi_mutex_wait(0);
-		continue;
-	}
-
-	if (!(x54x_dev->Status & STAT_INIT) && x54x_dev->MailboxInit && dev->MailboxReq) {
-		x54x_wait_for_poll();
-
-		x54x_do_mail(dev);
-	}
-
-	if (dev->ven_thread) {
-		dev->ven_thread(dev);
-	}
-
-	scsi_mutex_wait(0);
+    if ((dev->Status & STAT_INIT) || (!dev->MailboxInit && !dev->BIOSMailboxInit) || (!dev->MailboxReq && !dev->BIOSMailboxReq)) {
+	/* If we did not get anything, do nothing and wait 10 us. */
+	dev->timer_period = 10LL * TIMER_USEC;
+	return;
     }
 
-    x54x_log("%s: Callback: polling stopped.\n", dev->name);
-}
+    dev->temp_period = dev->media_period = 0LL;
 
+    if (!(x54x_dev->Status & STAT_INIT) && x54x_dev->MailboxInit && dev->MailboxReq)
+	x54x_do_mail(dev);
 
-void
-x54x_busy(uint8_t set)
-{
-    busy = !!set;
-    if (!set)
-	    thread_set_event((event_t *) wake_poll_thread);
-}
+    if (dev->ven_callback)
+	dev->ven_callback(dev);
 
-
-void
-x54x_thread_start(x54x_t *dev)
-{
-    if (!poll_tid) {
-	x54x_log("Starting thread...\n");
-	poll_tid = thread_create(x54x_cmd_thread, dev);
-    }
-}
-
-
-uint8_t
-x54x_is_busy(void)
-{
-    return(!!busy);
-}
-
-
-void
-x54x_set_wait_event(void)
-{
-    thread_set_event((event_t *)wait_evt);
+    period = (1000000.0 / x54x_dev->ha_bps) * ((double) TIMER_USEC) * ((double) dev->temp_period);
+    dev->timer_period = dev->media_period + ((int64_t) period) + (40LL * TIMER_USEC);
+    x54x_log("Temporary period: %" PRId64 " us (%" PRIi64 " periods)\n", dev->timer_period, dev->temp_period);
 }
 
 
@@ -1518,31 +1468,24 @@ x54x_out(uint16_t port, uint8_t val, void *priv)
     switch (port & 3) {
 	case 0:
 		if ((val & CTRL_HRST) || (val & CTRL_SRST)) {
-			x54x_busy(1);
 			reset = (val & CTRL_HRST);
 			x54x_log("Reset completed = %x\n", reset);
 			x54x_reset_ctrl(dev, reset);
 			x54x_log("Controller reset: ");
-			x54x_busy(0);
 			break;
 		}
 
 		if (val & CTRL_IRST) {
-			x54x_busy(1);
 			clear_irq(dev);
 			x54x_log("Interrupt reset: ");
-			x54x_busy(0);
 		}
 		break;
 
 	case 1:
 		/* Fast path for the mailbox execution command. */
 		if ((val == CMD_START_SCSI) && (dev->Command == 0xff)) {
-			x54x_busy(1);
 			dev->MailboxReq++;
-			x54x_set_wait_event();
 			x54x_log("Start SCSI command: ");
-			x54x_busy(0);
 			return;
 		}
 		if (dev->ven_fast_cmds) {
@@ -1609,7 +1552,6 @@ x54x_out(uint16_t port, uint8_t val, void *priv)
 					break;
 
 				case CMD_MBINIT: /* mailbox initialization */
-					x54x_busy(1);
 					dev->Mbx24bit = 1;
 
 					mbi = (MailboxInit_t *)dev->CmdBuf;
@@ -1628,7 +1570,6 @@ x54x_out(uint16_t port, uint8_t val, void *priv)
 					dev->Status &= ~STAT_INIT;
 					dev->DataReplyLeft = 0;
 					x54x_log("Mailbox init: ");
-					x54x_busy(0);
 					break;
 
 				case CMD_BIOSCMD: /* execute BIOS */
@@ -1962,22 +1903,11 @@ x54x_init(device_t *info)
     dev->bus = info->flags;
 
     timer_add(x54x_reset_poll, &dev->ResetCB, &dev->ResetCB, dev);
+    dev->timer_period = 10LL * TIMER_USEC;
+    timer_add(x54x_cmd_callback, &dev->timer_period, TIMER_ALWAYS_ENABLED, dev);
 
     x54x_dev = dev;
 
-    scsi_mutex(1);
-
-    wake_poll_thread = thread_create_event();
-    thread_started = thread_create_event();
-
-    /* Create a waitable event. */
-    evt = thread_create_event();
-    wait_evt = thread_create_event();
-
-    x54x_thread_start(dev);
-    thread_wait_event((event_t *) thread_started, -1);
-    thread_reset_event((event_t *) thread_started);
-
     return(dev);
 }
 
@@ -1990,17 +1920,8 @@ x54x_close(void *priv)
     if (dev) {
 	x54x_dev = NULL;
 
-        /* Tell the thread to terminate. */
-	if (poll_tid != NULL) {
-		x54x_busy(0);
-
-		x54x_log("Waiting for SCSI thread to end...\n");
-		/* Wait for the end event. */
-		thread_wait((event_t *) poll_tid, -1);
-		x54x_log("SCSI thread ended\n");
-
-		poll_tid = NULL;
-	}
+	/* Tell the timer to terminate. */
+	dev->timer_period = 0LL;
 
 	dev->MailboxInit = dev->BIOSMailboxInit = 0;
 	dev->MailboxCount = dev->BIOSMailboxCount = 0;
@@ -2009,28 +1930,6 @@ x54x_close(void *priv)
 	if (dev->ven_data)
 		free(dev->ven_data);
 
-	if (wait_evt) {
-		thread_destroy_event((event_t *) evt);
-		evt = NULL;
-	}
-
-	if (evt) {
-		thread_destroy_event((event_t *) evt);
-		evt = NULL;
-	}
-
-	if (thread_started) {
-		thread_destroy_event((event_t *) thread_started);
-		thread_started = NULL;
-	}
-
-	if (wake_poll_thread) {
-		thread_destroy_event((event_t *) wake_poll_thread);
-		wake_poll_thread = NULL;
-	}
-
-	scsi_mutex(0);
-
 	if (dev->nvr != NULL)
 		free(dev->nvr);
 
diff --git a/src/scsi/scsi_x54x.h b/src/scsi/scsi_x54x.h
index b4380fc89..c9b0d190e 100644
--- a/src/scsi/scsi_x54x.h
+++ b/src/scsi/scsi_x54x.h
@@ -11,14 +11,14 @@
  *		of SCSI Host Adapters made by Mylex.
  *		These controllers were designed for various buses.
  *
- * Version:	@(#)scsi_x54x.h	1.0.4	2017/12/15
+ * Version:	@(#)scsi_x54x.h	1.0.5	2018/03/07
  *
  * Authors:	TheCollector1995, <mariogplayer@gmail.com>
  *		Miran Grca, <mgrca8@gmail.com>
  *		Fred N. van Kempen, <decwiz@yahoo.com>
  *
- *		Copyright 2016,2017 Miran Grca.
- *		Copyright 2017 Fred N. van Kempen.
+ *		Copyright 2016-2018 Miran Grca.
+ *		Copyright 2017,2018 Fred N. van Kempen.
  */
 #ifndef SCSI_X54X_H
 
@@ -332,6 +332,10 @@ typedef struct {
     char	vendor[16];			/* name of device vendor */
     char	name[16];			/* name of device */
 
+    int64_t	timer_period, temp_period;
+    int64_t	media_period;
+    double	ha_bps;				/* bytes per second */
+
     int8_t	Irq;
     uint8_t	IrqEnabled;
 
@@ -429,8 +433,8 @@ typedef struct {
     /* Pointer to a structure of vendor-specific data that only the vendor-specific code can understand */
     void	*ven_data;
 
-    /* Pointer to a function that performs vendor-specific operation during the thread */
-    void	(*ven_thread)(void *p);
+    /* Pointer to a function that performs vendor-specific operation during the timer callback */
+    void	(*ven_callback)(void *p);
     /* Pointer to a function that executes the second parameter phase of the vendor-specific command */
     void	(*ven_cmd_phase1)(void *p);
     /* Pointer to a function that gets the host adapter ID in case it has to be read from a non-standard location */
@@ -487,10 +491,6 @@ typedef struct
 
 
 extern void	x54x_reset_ctrl(x54x_t *dev, uint8_t Reset);
-extern void	x54x_busy(uint8_t set);
-extern void	x54x_thread_start(x54x_t *dev);
-extern void	x54x_set_wait_event(void);
-extern uint8_t	x54x_is_busy(void);
 extern void	x54x_buf_alloc(uint8_t id, uint8_t lun, int length);
 extern void	x54x_buf_free(uint8_t id, uint8_t lun);
 extern uint8_t	x54x_mbo_process(x54x_t *dev);
diff --git a/src/video/vid_s3.c b/src/video/vid_s3.c
index 8f84b85ad..21034e812 100644
--- a/src/video/vid_s3.c
+++ b/src/video/vid_s3.c
@@ -8,7 +8,7 @@
  *
  *		S3 emulation.
  *
- * Version:	@(#)vid_s3.c	1.0.5	2018/02/09
+ * Version:	@(#)vid_s3.c	1.0.6	2018/03/07
  *
  * Authors:	Sarah Walker, <http://pcem-emulator.co.uk/>
  *		Miran Grca, <mgrca8@gmail.com>
@@ -115,8 +115,8 @@ typedef struct s3_t
 
         struct
         {
-                uint8_t subsys_cntl;
-                uint8_t setup_md;
+                uint16_t subsys_cntl;
+                uint16_t setup_md;
                 uint8_t advfunc_cntl;
                 uint16_t cur_y;
                 uint16_t cur_x;
diff --git a/src/win/86Box.rc b/src/win/86Box.rc
index 546d11ef8..7122bf0f5 100644
--- a/src/win/86Box.rc
+++ b/src/win/86Box.rc
@@ -8,7 +8,7 @@
  *
  *		Application resource script for Windows.
  *
- * Version:	@(#)86Box.rc	1.0.30	2018/02/11
+ * Version:	@(#)86Box.rc	1.0.31	2018/03/06
  *
  * Authors:	Miran Grca, <mgrca8@gmail.com>
  *		Fred N. van Kempen, <decwiz@yahoo.com>
@@ -473,16 +473,16 @@ BEGIN
     PUSHBUTTON      "&Remove",IDC_BUTTON_HDD_REMOVE,198,137,62,10
     COMBOBOX        IDC_COMBO_HD_BUS,33,117,90,12,CBS_DROPDOWNLIST | 
                     WS_VSCROLL | WS_TABSTOP
-    LTEXT           "Bus:",IDT_1721,7,118,24,8
+    LTEXT           "Bus:",IDT_1721,7,119,24,8
     COMBOBOX        IDC_COMBO_HD_CHANNEL,170,117,90,12,CBS_DROPDOWNLIST | 
                     WS_VSCROLL | WS_TABSTOP
-    LTEXT           "Channel:",IDT_1722,131,118,38,8
+    LTEXT           "Channel:",IDT_1722,131,119,38,8
     COMBOBOX        IDC_COMBO_HD_ID,170,117,22,12,CBS_DROPDOWNLIST | 
                     WS_VSCROLL | WS_TABSTOP
-    LTEXT           "ID:",IDT_1723,131,118,38,8
+    LTEXT           "ID:",IDT_1723,131,119,38,8
     COMBOBOX        IDC_COMBO_HD_LUN,239,117,22,12,CBS_DROPDOWNLIST | 
                     WS_VSCROLL | WS_TABSTOP
-    LTEXT           "LUN:",IDT_1724,200,118,38,8
+    LTEXT           "LUN:",IDT_1724,200,119,38,8
     COMBOBOX        IDC_COMBO_HD_CHANNEL_IDE,170,117,90,12,CBS_DROPDOWNLIST | 
                     WS_VSCROLL | WS_TABSTOP
 END
@@ -510,16 +510,16 @@ BEGIN
     LTEXT           "File name:",IDT_1731,7,7,204,9
     COMBOBOX        IDC_COMBO_HD_BUS,33,71,58,12,CBS_DROPDOWNLIST | 
                     WS_VSCROLL | WS_TABSTOP
-    LTEXT           "Bus:",IDT_1721,7,72,24,8
+    LTEXT           "Bus:",IDT_1721,7,73,24,8
     COMBOBOX        IDC_COMBO_HD_CHANNEL,134,71,77,12,CBS_DROPDOWNLIST | 
                     WS_VSCROLL | WS_TABSTOP
-    LTEXT           "Channel:",IDT_1722,99,72,34,8
+    LTEXT           "Channel:",IDT_1722,99,73,34,8
     COMBOBOX        IDC_COMBO_HD_ID,133,71,26,12,CBS_DROPDOWNLIST | 
                     WS_VSCROLL | WS_TABSTOP
-    LTEXT           "ID:",IDT_1723,117,72,15,8
+    LTEXT           "ID:",IDT_1723,117,73,15,8
     COMBOBOX        IDC_COMBO_HD_LUN,185,71,26,12,CBS_DROPDOWNLIST | 
                     WS_VSCROLL | WS_TABSTOP
-    LTEXT           "LUN:",IDT_1724,168,72,15,8
+    LTEXT           "LUN:",IDT_1724,168,73,15,8
     COMBOBOX        IDC_COMBO_HD_CHANNEL_IDE,134,71,77,12,CBS_DROPDOWNLIST | 
                     WS_VSCROLL | WS_TABSTOP
     LTEXT           "Progress:",IDT_1752,7,7,204,9
@@ -537,7 +537,7 @@ BEGIN
     LTEXT           "Floppy drives:",IDT_1737,7,7,43,8
     COMBOBOX        IDC_COMBO_FD_TYPE,33,85,90,12,CBS_DROPDOWNLIST | 
                     WS_VSCROLL | WS_TABSTOP
-    LTEXT           "Type:",IDT_1738,7,86,24,8
+    LTEXT           "Type:",IDT_1738,7,87,24,8
     CONTROL         "Turbo timings",IDC_CHECKTURBO,"Button",
                     BS_AUTOCHECKBOX | WS_TABSTOP,131,86,64,10
     CONTROL         "Check BPB",IDC_CHECKBPB,"Button",
@@ -554,34 +554,37 @@ BEGIN
     LTEXT           "CD-ROM drives:",IDT_1739,7,7,50,8
     COMBOBOX        IDC_COMBO_CD_BUS,33,85,90,12,CBS_DROPDOWNLIST | 
                     WS_VSCROLL | WS_TABSTOP
-    LTEXT           "Bus:",IDT_1740,7,86,24,8
+    LTEXT           "Bus:",IDT_1740,7,87,24,8
     COMBOBOX        IDC_COMBO_CD_ID,170,85,22,12,CBS_DROPDOWNLIST | 
                     WS_VSCROLL | WS_TABSTOP
-    LTEXT           "ID:",IDT_1741,131,86,38,8
+    LTEXT           "ID:",IDT_1741,131,87,38,8
     COMBOBOX        IDC_COMBO_CD_LUN,239,85,22,12,CBS_DROPDOWNLIST | 
                     WS_VSCROLL | WS_TABSTOP
-    LTEXT           "LUN:",IDT_1742,200,86,38,8
+    LTEXT           "LUN:",IDT_1742,200,87,38,8
     COMBOBOX        IDC_COMBO_CD_CHANNEL_IDE,170,85,90,12,CBS_DROPDOWNLIST | 
                     WS_VSCROLL | WS_TABSTOP
-    LTEXT           "Channel:",IDT_1743,131,86,38,8
+    LTEXT           "Channel:",IDT_1743,131,87,38,8
+    COMBOBOX        IDC_COMBO_CD_SPEED,33,105,90,12,CBS_DROPDOWNLIST | 
+                    WS_VSCROLL | WS_TABSTOP
+    LTEXT           "Speed:",IDT_1758,7,107,24,8
     CONTROL         "List1",IDC_LIST_ZIP_DRIVES,"SysListView32",LVS_REPORT | 
                     LVS_SHOWSELALWAYS | LVS_SINGLESEL | WS_BORDER | 
-                    WS_TABSTOP,7,117,253,60
-    LTEXT           "ZIP drives:",IDT_1739,7,107,50,8
-    COMBOBOX        IDC_COMBO_ZIP_BUS,33,184,90,12,CBS_DROPDOWNLIST | 
+                    WS_TABSTOP,7,137,253,60
+    LTEXT           "ZIP drives:",IDT_1739,7,127,50,8
+    COMBOBOX        IDC_COMBO_ZIP_BUS,73,204,90,12,CBS_DROPDOWNLIST | 
                     WS_VSCROLL | WS_TABSTOP
-    LTEXT           "Bus:",IDT_1753,7,185,24,8
-    COMBOBOX        IDC_COMBO_ZIP_ID,170,184,22,12,CBS_DROPDOWNLIST | 
+    LTEXT           "Bus:",IDT_1753,57,206,14,8
+    COMBOBOX        IDC_COMBO_ZIP_ID,190,204,22,12,CBS_DROPDOWNLIST | 
                     WS_VSCROLL | WS_TABSTOP
-    LTEXT           "ID:",IDT_1754,131,185,38,8
-    COMBOBOX        IDC_COMBO_ZIP_LUN,239,184,22,12,CBS_DROPDOWNLIST | 
+    LTEXT           "ID:",IDT_1754,171,206,18,8
+    COMBOBOX        IDC_COMBO_ZIP_LUN,239,204,22,12,CBS_DROPDOWNLIST | 
                     WS_VSCROLL | WS_TABSTOP
-    LTEXT           "LUN:",IDT_1755,200,185,38,8
-    COMBOBOX        IDC_COMBO_ZIP_CHANNEL_IDE,170,184,90,12,CBS_DROPDOWNLIST | 
+    LTEXT           "LUN:",IDT_1755,220,206,18,8
+    COMBOBOX        IDC_COMBO_ZIP_CHANNEL_IDE,200,204,60,12,CBS_DROPDOWNLIST | 
                     WS_VSCROLL | WS_TABSTOP
-    LTEXT           "Channel:",IDT_1756,131,185,38,8
+    LTEXT           "Channel:",IDT_1756,171,206,28,8
     CONTROL         "ZIP 250",IDC_CHECK250,"Button",
-                    BS_AUTOCHECKBOX | WS_TABSTOP,7,204,64,10
+                    BS_AUTOCHECKBOX | WS_TABSTOP,7,204,44,10
 END
 
 
@@ -955,6 +958,7 @@ BEGIN
     IDS_2175	"ZIP images (*.IM?;*.ZDI)\0*.IM?;*.ZDI\0All files (*.*)\0*.*\0"
     IDS_2176	"ZIP images (*.IM?;*.ZDI)\0*.IM?;*.ZDI\0"
     IDS_2177	"ZIP %i (%03i): %ls"
+    IDS_2178	"Speed"
 
     IDS_4096    "Hard disk (%s)"
     IDS_4097	"%01i:%01i"
diff --git a/src/win/resource.h b/src/win/resource.h
index 3112d462a..af9d94b77 100644
--- a/src/win/resource.h
+++ b/src/win/resource.h
@@ -8,7 +8,7 @@
  *
  *		Windows resource defines.
  *
- * Version:	@(#)resource.h	1.0.21	2018/02/11
+ * Version:	@(#)resource.h	1.0.22	2018/03/06
  *
  * Authors:	Sarah Walker, <http://pcem-emulator.co.uk/>
  *		Miran Grca, <mgrca8@gmail.com>
@@ -90,6 +90,7 @@
 #define IDT_1755		1755	/* LUN: */
 #define IDT_1756		1756	/* Channel: */
 #define IDT_1757		1757	/* Progress: */
+#define IDT_1758		1758	/* Speed: */
 
 
 /*
@@ -195,6 +196,7 @@
 #define IDC_COMBO_ZIP_LUN	1163
 #define IDC_COMBO_ZIP_CHANNEL_IDE 1164
 #define IDC_CHECK250		1165
+#define IDC_COMBO_CD_SPEED	1166
 
 #define IDC_SLIDER_GAIN		1180	/* sound gain dialog */
 
diff --git a/src/win/win_settings.c b/src/win/win_settings.c
index fd5c222f2..6a746ae53 100644
--- a/src/win/win_settings.c
+++ b/src/win/win_settings.c
@@ -8,7 +8,7 @@
  *
  *		Windows 86Box Settings dialog handler.
  *
- * Version:	@(#)win_settings.c	1.0.40	2018/03/06
+ * Version:	@(#)win_settings.c	1.0.41	2018/03/07
  *
  * Author:	Miran Grca, <mgrca8@gmail.com>
  *
@@ -3961,6 +3961,7 @@ static BOOL win_settings_cdrom_drives_recalc_list(HWND hwndList)
 	{
 		fsid = combo_id_to_format_string_id(temp_cdrom_drives[i].bus_type);
 
+		lvI.iSubItem = 0;
 		switch (temp_cdrom_drives[i].bus_type)
 		{
 			case CDROM_BUS_DISABLED:
@@ -3989,6 +3990,21 @@ static BOOL win_settings_cdrom_drives_recalc_list(HWND hwndList)
 
 		if (ListView_InsertItem(hwndList, &lvI) == -1)
 			return FALSE;
+
+		lvI.iSubItem = 1;
+		if (temp_cdrom_drives[i].bus_type == CDROM_BUS_DISABLED)
+			lvI.pszText = plat_get_string(IDS_2152);
+		else {
+			wsprintf(szText, L"%ix", temp_cdrom_drives[i].speed);
+			lvI.pszText = szText;
+		}
+		lvI.iItem = i;
+		lvI.iImage = 0;
+
+		if (ListView_SetItem(hwndList, &lvI) == -1)
+		{
+			return FALSE;
+		}
 	}
 
 	return TRUE;
@@ -4102,7 +4118,7 @@ static BOOL win_settings_cdrom_drives_init_columns(HWND hwndList)
 	lvc.iSubItem = 0;
 	lvc.pszText = plat_get_string(IDS_2082);
 
-	lvc.cx = 392;
+	lvc.cx = 342;
 	lvc.fmt = LVCFMT_LEFT;
 
 	if (ListView_InsertColumn(hwndList, 0, &lvc) == -1)
@@ -4110,6 +4126,17 @@ static BOOL win_settings_cdrom_drives_init_columns(HWND hwndList)
 		return FALSE;
 	}
 
+	lvc.iSubItem = 1;
+	lvc.pszText = plat_get_string(IDS_2178);
+
+	lvc.cx = 50;
+	lvc.fmt = LVCFMT_LEFT;
+
+	if (ListView_InsertColumn(hwndList, 1, &lvc) == -1)
+	{
+		return FALSE;
+	}
+
 	return TRUE;
 }
 
@@ -4130,7 +4157,6 @@ static BOOL win_settings_zip_drives_init_columns(HWND hwndList)
 		return FALSE;
 	}
 
-
 	lvc.iSubItem = 1;
 	lvc.pszText = plat_get_string(IDS_2143);
 
@@ -4294,6 +4320,21 @@ static void win_settings_cdrom_drives_update_item(HWND hwndList, int i)
 	{
 		return;
 	}
+
+	lvI.iSubItem = 1;
+	if (temp_cdrom_drives[i].bus_type == CDROM_BUS_DISABLED)
+		lvI.pszText = plat_get_string(IDS_2152);
+	else {
+		wsprintf(szText, L"%ix", temp_cdrom_drives[i].speed);
+		lvI.pszText = szText;
+	}
+	lvI.iItem = i;
+	lvI.iImage = 0;
+
+	if (ListView_SetItem(hwndList, &lvI) == -1)
+	{
+		return;
+	}
 }
 
 static void win_settings_zip_drives_update_item(HWND hwndList, int i)
@@ -4367,6 +4408,13 @@ static void cdrom_add_locations(HWND hdlg)
 		}
 	}
 
+	h = GetDlgItem(hdlg, IDC_COMBO_CD_SPEED);
+	for (i = 1; i <= 52; i++)
+	{
+		wsprintf(lptsTemp, L"%ix", i);
+		SendMessage(h, CB_ADDSTRING, 0, (LPARAM) lptsTemp);
+	}
+
 	h = GetDlgItem(hdlg, IDC_COMBO_CD_ID);
 	for (i = 0; i < 16; i++)
 	{
@@ -4390,6 +4438,7 @@ static void cdrom_add_locations(HWND hdlg)
 
 	free(lptsTemp);
 }
+
 static void cdrom_recalc_location_controls(HWND hdlg, int assign_id)
 {
 	int i = 0;
@@ -4416,6 +4465,16 @@ static void cdrom_recalc_location_controls(HWND hdlg, int assign_id)
 	EnableWindow(h, FALSE);
 	ShowWindow(h, SW_HIDE);
 
+	h = GetDlgItem(hdlg, IDC_COMBO_CD_SPEED);
+	if (bus == CDROM_BUS_DISABLED) {
+		EnableWindow(h, FALSE);
+		ShowWindow(h, SW_HIDE);
+	} else {
+		ShowWindow(h, SW_SHOW);
+		EnableWindow(h, TRUE);
+		SendMessage(h, CB_SETCURSEL, temp_cdrom_drives[cdlv_current_sel].speed - 1, 0);
+	}
+
 	switch(bus)
 	{
 		case CDROM_BUS_ATAPI_PIO_ONLY:			/* ATAPI (PIO-only) */
@@ -4496,6 +4555,7 @@ static void zip_add_locations(HWND hdlg)
 
 	free(lptsTemp);
 }
+
 static void zip_recalc_location_controls(HWND hdlg, int assign_id)
 {
 	int i = 0;
@@ -4969,6 +5029,8 @@ win_settings_other_removable_devices_proc(HWND hdlg, UINT message, WPARAM wParam
 					}
 					cdrom_untrack(cdlv_current_sel);
 					assign = (temp_cdrom_drives[cdlv_current_sel].bus_type == b2) ? 0 : 1;
+					if (temp_cdrom_drives[cdlv_current_sel].bus_type == CDROM_BUS_DISABLED)
+						temp_cdrom_drives[cdlv_current_sel].speed = 8;
 					if ((b2 == CDROM_BUS_ATAPI_PIO_ONLY) && (temp_cdrom_drives[cdlv_current_sel].bus_type == CDROM_BUS_ATAPI_PIO_AND_DMA))
 						assign = 0;
 					else if ((b2 == CDROM_BUS_ATAPI_PIO_AND_DMA) && (temp_cdrom_drives[cdlv_current_sel].bus_type == CDROM_BUS_ATAPI_PIO_ONLY))
@@ -5030,6 +5092,20 @@ cdrom_bus_skip:
 					rd_ignore_change = 0;
 					return FALSE;
 
+				case IDC_COMBO_CD_SPEED:
+					if (rd_ignore_change)
+					{
+						return FALSE;
+					}
+
+					rd_ignore_change = 1;
+					h = GetDlgItem(hdlg, IDC_COMBO_CD_SPEED);
+					temp_cdrom_drives[cdlv_current_sel].speed = SendMessage(h, CB_GETCURSEL, 0, 0) + 1;
+					h = GetDlgItem(hdlg, IDC_LIST_CDROM_DRIVES);
+					win_settings_cdrom_drives_update_item(h, cdlv_current_sel);
+					rd_ignore_change = 0;
+					return FALSE;
+
 				case IDC_COMBO_ZIP_BUS:
 					if (rd_ignore_change)
 					{