diff --git a/sys/dev/aic7xxx/aic7xxx.seq b/sys/dev/aic7xxx/aic7xxx.seq
index 430bbb5d73a1..2d7c8049935e 100644
--- a/sys/dev/aic7xxx/aic7xxx.seq
+++ b/sys/dev/aic7xxx/aic7xxx.seq
@@ -505,8 +505,19 @@ p_command:
 
 	call	set_stcnt_from_hcnt
 
-	mvi	0x3d		call dma	# SCSIEN|SDMAEN|HDMAEN|
-						#   DIRECTION|FIFORESET
+	mvi	DFCNTRL, 0x3d			/*  SCSIEN|SDMAEN|HDMAEN
+						 * |DIRECTION|FIFORESET
+						 */
+p_command_dma:
+	test	SSTAT0, SDONE		jnz p_command_dma_done
+	test	SSTAT1, PHASEMIS	jz  p_command_dma
+	test	SSTAT0, SDONE		jnz p_command_dma_done
+	clr	DFCNTRL
+	jmp	ITloop
+p_command_dma_done:
+	and	DFCNTRL, 0xc7		/* ~(SCSIEN|SDMAEN|HDMAEN) */
+p_command_dma_clear:
+	test	DFCNTRL, 0x38		jnz p_command_dma_clear
 	jmp	ITloop
 
 /*
@@ -929,10 +940,12 @@ dma4:
  * actually off first lest we get an ILLSADDR.
  */
 dma5:
-	/* disable DMA, but maintain WIDEODD */
-	and	DFCNTRL,WIDEODD
+	/* Don't clobber an inprogress host data transfer */
+	test	DFSTATUS, MREQPEND	jnz dma5
+	/* disable DMA */
+	and	DFCNTRL, 0xc7		/* ~(SCSIEN|SDMAEN|HDMAEN|DIRECTION) */
 dma6:
-	test	DFCNTRL,0x38	jnz dma6  /* SCSIENACK|SDMAENACK|HDMAENACK */
+	test	DFCNTRL, HDMAENACK	jnz dma6 
 return:
 	ret
 
diff --git a/sys/dev/aic7xxx/aic7xxx_reg.h b/sys/dev/aic7xxx/aic7xxx_reg.h
index a185792d9314..d30d8b0dc34a 100644
--- a/sys/dev/aic7xxx/aic7xxx_reg.h
+++ b/sys/dev/aic7xxx/aic7xxx_reg.h
@@ -475,6 +475,7 @@
 #define		FIFORESET	0x01
 
 #define	DFSTATUS		0x094
+#define		MREQPEND	0x10
 #define		HDONE		0x08
 #define		FIFOEMP		0x01
 
@@ -527,7 +528,7 @@
 #define		MK_MESSAGE      0x80
 #define		DISCENB         0x40
 #define		TAG_ENB		0x20
-#define		TRACE_SCB	0x10
+#define		SPLIT_SG	0x10
 #define		ABORT_SCB	0x08
 #define		DISCONNECTED	0x04
 #define		SCB_TAG_TYPE	0x03
@@ -588,6 +589,16 @@
 
 #define DSPCISTATUS		0x086
 
+#define BRDCTL			0x01d
+#define		BRDDAT7		0x80
+#define		BRDDAT6		0x40
+#define		BRDDAT5		0x20
+#define		BRDSTB		0x10
+#define		BRDCS		0x08
+#define		BRDRW		0x04
+#define		BRDCTL1		0x02
+#define		BRDCTL0		0x01
+
 /*
  * Serial EEPROM Control (p. 4-92 in 7870 Databook)
  * Controls the reading and writing of an external serial 1-bit
@@ -621,7 +632,6 @@
 #define		SEECK		0x04
 #define		SEEDO		0x02
 #define		SEEDI		0x01
-
 /* ---------------------- Scratch RAM Offsets ------------------------- */
 /* These offsets are either to values that are initialized by the board's
  * BIOS or are specified by the sequencer code.