diff --git a/sys/dev/dec/dec_boot.h b/sys/dev/dec/dec_boot.h
index aba49293f29f..24c57b9da86f 100644
--- a/sys/dev/dec/dec_boot.h
+++ b/sys/dev/dec/dec_boot.h
@@ -1,4 +1,4 @@
-/*	$NetBSD: dec_boot.h,v 1.3 2000/06/21 14:57:21 matt Exp $	*/
+/*	$NetBSD: dec_boot.h,v 1.4 2002/04/03 04:05:05 lukem Exp $	*/
 
 /*
  * Copyright (c) 1992, 1993
@@ -37,18 +37,41 @@
  *
  *	@(#)dec_boot.h	8.1 (Berkeley) 6/10/93
  *
- * devDiskLabel.h --
- *
- *      This defines the disk label that Sun writes on the 0'th sector of
- *      the 0'th cylinder of its SMD disks.  The disk label contains some
- *      geometry information and also the division of the disk into a
- *      number of partitions.  Each partition is identified to the drive
- *      by a different unit number.
- *
  * from: Header: /sprite/src/kernel/dev/RCS/devDiskLabel.h,
  *	v 9.4 90/03/01 12:22:36 jhh Exp  SPRITE (Berkeley)
  */
 
+/*
+ * Copyright (c) 1994, 1999 Christopher G. Demetriou
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *      This product includes software developed by Christopher G. Demetriou
+ *      for the NetBSD Project.
+ * 4. The name of the author may not be used to endorse or promote products
+ *    derived from this software without specific prior written permission
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
 #ifndef _DEV_DEC_DEC_BOOT_H_
 #define _DEV_DEC_DEC_BOOT_H_
 
@@ -60,8 +83,47 @@
  * after the boot information expected by the PROM boot loader.
  */
 
-/* PMAX (DECstation / MIPS) boot block information
+/*
+ *	Alpha (disk, but also tape) Boot Block.
+ * 
+ * See Section (III) 3.6.1 of the Alpha Architecture Reference Manual.
  */
+
+struct alpha_boot_block {
+	u_int64_t bb_data[63];		/* data (disklabel, also as below) */
+	u_int64_t bb_cksum;		/* checksum of the boot block,
+					 * taken as u_int64_t's
+					 */
+};
+#define	bb_secsize	bb_data[60]	/* secondary size (blocks) */
+#define	bb_secstart	bb_data[61]	/* secondary start (blocks) */
+#define	bb_flags	bb_data[62]	/* unknown flags (set to zero) */
+
+#define	ALPHA_BOOT_BLOCK_OFFSET		0	/* offset of boot block. */
+#define	ALPHA_BOOT_BLOCK_BLOCKSIZE	512	/* block size for sector
+						 * size/start, and for boot
+						 * block itself.
+						 */
+
+#define	ALPHA_BOOT_BLOCK_CKSUM(bb,cksum)				\
+	do {								\
+		const struct alpha_boot_block *_bb = (bb);		\
+		u_int64_t _cksum;					\
+		int _i;							\
+									\
+		_cksum = 0;						\
+		for (_i = 0;						\
+		    _i < (sizeof _bb->bb_data / sizeof _bb->bb_data[0]); \
+		    _i++)						\
+			_cksum += _bb->bb_data[_i];			\
+		*(cksum) = _cksum;					\
+	} while (0)
+
+
+/*
+ *	PMAX (DECstation / MIPS) boot block information
+ */
+
 /*
  * If mode is 0, there is just one sequence of blocks and one Dec_BootMap
  * is used.  If mode is 1, there are multiple sequences of blocks
@@ -94,8 +156,9 @@ struct pmax_boot_block {
 #define PMAX_BOOT_BLOCK_OFFSET		0
 #define PMAX_BOOT_BLOCK_BLOCKSIZE	512
 
-/* VAX boot block information
- *
+
+/*
+ *	VAX boot block information
  */
 struct vax_boot_block {
 /* Note that these don't overlap any of the pmax boot block