🚀 go-pugleaf

Subject: RP06 bootblock bug + fix (#104)
Index:	sys/mdec/hpuboot.s 2.11BSD

Description:
	The block 0 bootstrap for the RP04/5/6 does not work.  This means
	that the boot process had to be loaded from tape rather than disc.

Repeat-By:
	Install 2.11BSD on a RP06 system, copy the /mdec/hpuboot boot code
	to disc with "dd" and attempt a hardware boot of the disc.

Fix:
	The bug was introduced when the boot blocks were rewritten back 
	around May 1991, a 'mov' instruction should have been an 'add'
	instruction.

	Apply the patch below and reinstall 'hpuboot' into /mdec.

	Thanks to Lasse Ylitalo & Johnny Billquist for finding the problem
	and providing the fix.
==================================cut here=================================
*** /sys/mdec/hpuboot.s.old	Tue Mar 10 15:10:29 1992
--- /sys/mdec/hpuboot.s	Wed Jan 27 09:02:59 1993
***************
*** 13,18 ****
--- 13,21 ----
  /		  the keyboard had to be removed to make room for the 
  /		  code which understands the new directory structure on disc
  
+ / 930124 Fixed major bug that made booting impossible.
+ /        Lasse Ylitalo & Johnny Billquist
+ 
  / constants:
  CLSIZE	= 2.			/ physical disk blocks per logical block
  CLSHFT	= 1.			/ shift to multiply by CLSIZE
***************
*** 227,233 ****
  	div	$22.,r0
  	swab	r0
  	bis	r1,r0
! 	mov	$hpcs2,r3
  	mov	unit,(r3)
  	mov	r0,-(r3)
  	mov	$buf,-(r3)
--- 230,236 ----
  	div	$22.,r0
  	swab	r0
  	bis	r1,r0
! 	add	$hpcs2,r3	/ 930124 LY&JB
  	mov	unit,(r3)
  	mov	r0,-(r3)
  	mov	$buf,-(r3)