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       RING - PAD RING router

       RING source result [ stat ]

       source defines two input	files:
	      -- the file describing the input netlist (MBK_IN_LO(1) format).

	      -- the parameter file: source.rin
	      This  file  consists  in	5 sections: 4 for the pad placement on
	      circuit sides, one to define the power sypply width  (in	lambda

			east ()	# none pad at east side.
			north (
			p_pck p_i0 p_i1
			south (p_vssb p_vddb p_i2)
			width (vss 50 vdd 80)

	      Separators  (spaces,  tabulations	 and new line) are allowed be-
	      tween instance names.

	      -- east(), north(), south(), west() define the relative pad  or-
	      der.  They use the pad instance names.

	      For the north() and south() sections, the	instance name declara-
	      tion are from the	left (first pad) to the	right (last pad).

	      For the east() and west()	sections, the instance	name  declara-
	      tion are from the	bottom (first pad) to the top (last pad).

	      Any section may be missing. It means so the revalive side	has no
	      pad, however at least one	side must has one pad.

	      -- the width() section  is  optional  and	 describes  the	 power
	      (vdd), and ground	(vss) track width.

       result defines the output filename.

	      This   file   contains   the   layout   of  the  routed  circuit
	      (MBK_OUT_PH(1) format).
		     example: result.ap

	      RING uses	a pad library whose path directory is defined with the
	      MBK_CATA_LIB(1)  environment  variable.	It also	uses a catalog
	      filename which is	defined	with the MBK_CATAL_NAME(1) environment
	      The  catalog  must  contain  all the pad model names used	in the
	      circuit. The core	model-name must	not be present in the catalog.

	      Part of catalog file:
		     a2_y  C
		     high_y  C
		     pck_sp C
		     piot_sp  C
		     pvssick_sp	 C
		     pvdde_sp C
		     pvddi_sp C

       [stat] (optional	parameter) defines another output file:

	      -- the statistic file: result.stat

	      It contains data about length  (lambdas)	and  area  (lambdas  *
	      lambdas)	in ALU1	and ALU2, for each equipotential. It describes
	      how many vias were placed.

		     example: *** STATISTIC FILE < result.stat > ***

	      Equipotential list :

	      index|   name   |lgth A1|lgth A2|area A1|area A2|	nb vias
	       60  |	  vss |	9034  |	4408  |	614288|	454024|	1128
	       59  |	  vdd |	7494  |	3968  |	574248|	408704|	1128
	       54  | b2_coeur |	2253  |	1899  |	  2253|	  3798|	   4
	      Total length alu1	 :	  18781	(lambdas)
	      Total length alu2	 :	  10275	(lambdas)
	      Total area alu1	 :	1190789	(lambdas * lambdas)
	      Total area alu2	 :	 866526	(lambdas * lambdas)
	      Total of vias	 :	   2260

       MBK_IN_LO(1) defines the	input file format for the netlist.
       MBK_IN_PH(1) defines the	input file format for the layout.
       MBK_OUT_PH(1) defines the output	file format for	the layout.
       MBK_CATAL_NAME(1) defines the catalog filename.
       MBK_CATA_LIB(1) defines the library pad cells directory.
       MBK_WORK_LIB(1) defines the work	directory.

       RING performs the physical routing between  core	 of  circuit  and  pad
       ring.  RING is not a floor plan router and allows only one core.

       A  core is designed, for	example, with the standard cells placer	ocp(1)
       and router nero(1), which places	the input and output connectors	on the
       abutment	 box.  The  physical core connectors must be separated by more
       than one	pitch in any metal (in ALU1 or ALU2).

       Netlist and layout views	relative to the	same figure must have the same
       name. For example, the netlist core name	and the	routed core name.

       RING  performs  an  automatic placement of the pad ring and core. It is
       not necessary to	place pads, but	only to	describe their relative	 posi-
       tion on each side, in the parameter file	(source.rin).

       Distance	 between the first track and any instance (pad or core)	is the
       pitch so	5 lambdas.

       Let be the circuit netlist and core.ap  the  routed  core.   80
       lambdas	for  supply track width	and the	pad placement are described as


	      #	This is	a comment: 1 comment per line
	      north(p_a1 p_a2 p_a3 p_a4)
	      p_i1 #another comment: the rest of the line
	      east(p_b4	p_b3 p_b2 p_b1)
	      west(p_f1	p_f2 p_f3 p_f4)
	      vdd 80
	      vss 80

	      We want a	ring of	pads as	follow:

		     |		  |p_a1|p_a2|p_a3|p_a4|		       |
		     |p_f4|					  |p_b1|
		     |----|	       +-------+		  |----|
		     |p_f3|	       |       |		  |p_b2|
		     |----|	       | CORE  |		  |----|
		     |p_f2|	       |       |		  |p_b3|
		     |----|	       +-------+		  |----|
		     |p_f1|					  |p_b4|
		     |		  |p_i1|p_i2|p_i3|p_i4|		       |

	      In order to obtain the routed circuit (chipr.ap):

	      >	ring chip chipr

       genlib(1) lvx(1)	ocp(1) nero(1) druc(1)

       Physical	core must have at least	one physical connector by side,	other-
       wise it can't place pads	correctly, and maybe dump a core file.

       Whenever	 lots of core connectors (bus) are placed close	ones from each
       others, RING may	have problems to connect pad connectors	placed just in
       front  of them.	In such	a case,	it is recommended to not have pad con-
       nectors at that place and thus to place an instance pad without connec-
       tor (as pvdde_sp) or to cut the bus into	several	parts to let space be-
       tween connectors.

       When core connectors are	to close from corners, RING sometimes connects
       those  one  to supply rings, to solve this bug, move core connectors or
       change pad placement. In	any case, use  druc(1)	or  lvx(1)  to	detect

       Supply vdd and vss pads (resp. pvddi_sp and pvssi_sp) must be placed as
       close as	possible of the	core side middle (i.e. not  in	the  corners).
       Otherwise,  RING	 cannot	link supply pad	connector to ring supplies and
       exits with a error message.

       Supply tracks from pads and core	are  connected	at  the	 supply	 ring.
       There  is sometimes few problems	when core and pad tracks are opposite.
       Move pads usually corrects problem.

ASIM/LIP6			October	1, 1997			       RING(1)


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