WIP: Make dynamic memory allocation work.

... by turning off the right PI level.

src/system/deuna.defs1

@@ -42,7 +42,7 @@ $$TEMP==1
 DEFSYM	%UNVEC==120		;Interrupt vector
 DEFSYM	%UNBAS==3,,774510	;Base of Unibus register address space
 
-DEFSYM	%UNR0==%UNBAS		;PCSR0
+DEFSYM	%UNR0==%UNBAS		;PCSR0 - flags and command
 .BEGIN %UN0			;Bits in PCSR0
  SERI==1_15.			;status error
  PCEI==1_14.			;port command error
@@ -56,8 +56,9 @@ DEFSYM	%UNR0==%UNBAS		;PCSR0
  INTR==1_7.			;or of bits 15-8
  INTE==1_6.			;interrupt enable
  RSET==1_5.			;reset
+ CMD==<.BP 17,0>		;command field - see %UNCMD
 .END %UN0
-.BEGIN %UNCMD			;Command field in PCSR0
+.BEGIN %UNCMD			;Port commands
  NOP==0
  GETPCB==1
  GETCMD==2
@@ -69,11 +70,22 @@ DEFSYM	%UNR0==%UNBAS		;PCSR0
  STOP==17
 .END %UNCMD
 
-DEFSYM	%UNR1==%UNBAS+2		;PCSR1
+DEFSYM	%UNR1==%UNBAS+2		;PCSR1 - status
+.BEGIN %UN1
+ STER==1_15.			;error occurred
+ ERROR==<.BP 177_8.,0>		;error code, if STER
+ PCTO==1_7.			;Unibus timeout during port command
+ ID==<.BP 7_4.,0>		;0 for DEUNA, 1 for DELUA
+ STATE==<.BP 17,0>		;functional state
+.END %UN1
 
-DEFSYM	%UNR2==%UNBAS+4		;PCSR2
+DEFSYM	%UNR2==%UNBAS+4		;PCSR2 - 16 low bits of PCB address
 
-DEFSYM	%UNR3==%UNBAS+6		;PCSR3
+DEFSYM	%UNR3==%UNBAS+6		;PCSR3 - 16 high bits of PCB address
+
+.BEGIN %UNPCx			;Port Control Block
+ FUNC==<.BP %NE8,0>		;function - see %UNAF
+.END %UNPCx
 
 .BEGIN %UNAF			;Ancillary function codes in PCB
  NOP==0

src/system/ether.1

@@ -16,6 +16,10 @@
 ;;; along with this program. If not, see <https://www.gnu.org/licenses/>.
 
 ;FIXME The big one - interrupts? Compare with CHAOS...
+;  search "PI for Tape" in its.* - TTYCHN
+;PRM p4-3 - BR6/7 "high" vs BR4/5 "low" level - so that's what's being assigned above
+;  but which does the DEUNA get?
+;  and "CH-11 INTERRUPT ROUTINES" in chaos.* - copy at lower PI level
 ;FIXME Should we use input/output queues like IMP does?
 ;FIXME Use the style from TCP - this is a bit of a mix at the moment
 ;FIXME Use Johnny Eriksson's layout workaround for UBA half-write problem
@@ -409,34 +413,24 @@ UNADNI:	CPOPJ			;Call this after a DNI interrupt
 UNARCB:	0			;Have we seen an RCBI interrupt?
 ;FIXME A flags word would make more sense (if we ever need a second flag!)
 
-;FIXME For horrible hack below
-	BLOCK 2000-<.&1777>	;Align to a page boundary
-UNPGHK:	BLOCK 2000*%UNNPG
-
 BBLK
 
-;Initialise the DEUNA.
+; Configure and start the DEUNA.
 ;
 UNAINI:	MOVEI D,%UNNPG-1
 
 UNAIN1:
-IFN 0,[
-;FIXME This causes the core job to crash later...
-	PUSHJ P,TCALL		;Allocate a page of unshuffleable low core
-	 JRST IOMQ
-	  BUG HALT,[Couldn't allocate page for DEUNA]
+	CONI PI,Q		;Save PI status
+	ANDI Q,177
+	CONO PI,UTCOFF
+	PUSHJ P,IOMQ		;Allocate a page of unshuffleable low core
+	 BUG HALT,[Couldn't allocate page for DEUNA]
+	CONO PI,PICON(Q)	;Restore PI status
 
 	MOVEI B,MUETH		;Tag what it's being used for
 	DPB B,[MUR,,MEMBLT(A)]
 
 	LSH A,10.		;Save the pointer
-]
-IFE 0,[
-	MOVEI A,2000		;Use statically-allocated block above
-	IMUL A,D
-	ADDI A,UNPGHK
-]
-
 	MOVEM A,UNPAGS(D)
 
 	MOVE B,A
@@ -460,21 +454,24 @@ IFE 0,[
 
 	SOJGE D,UNAIN1
 
-	;Initialisation sequence from DELUA user guide, page 3-8 (42).
-	;This needs us to wait for an interrupt in several places, so
-	;UNACMD has magic interrupt-continuation behaviour.
+	; Initialisation sequence from DELUA user guide, page 3-8 (42).
+	; This needs us to wait for an interrupt in several places, so
+	; UNACMD has magic interrupt-continuation behaviour.
 
-	;Enable interrupts.
+	; Enable interrupts. (This can't be combined with a command.)
 	MOVEI A,%UN0"INTE
 	IOWRI A,%UNR0
 
-	;Set the PCB address.
+	; Set the PCB address.
 	HLRZ A,UNPAGU		;Low bits
 	IOWRI A,%UNR2
 	LSH A,-16.		;High bits
 	IOWRI A,%UNR3
 	MOVEI A,%UN0"DNI+%UNCMD"GETPCB	;Ack DNI as it's on after reset
-	PUSHJ P,UNACMD		;We've really returned to the caller here
+	PUSHJ P,UNACMD
+
+	; From now on, we've been called back from UNABRK, so we're operating
+	; at TTYCHN level.
 
 	;FIXME put IP address in too, use in ARP above
 	;Get the MAC address for ARP to use
@@ -644,7 +641,6 @@ UNARX1:	HRRZ A,W		;Wrap index around
 	 HLLZS W
 
 	HLRZ J,UNRXRP(W)	;Descriptor
-	HRRZ I,UNRXRP(W)	;XXX unibus
 
 	MOVE Q,1(J)		;Is there a packet in this buffer? (OWN=0)
 	TLNE Q,%UNTD"OWN