diff --git a/io-sram.tcl b/io-sram.tcl
index ec44235..dc70e55 100644
--- a/io-sram.tcl
+++ b/io-sram.tcl
@@ -1,3 +1,31 @@
 source util.tcl
 
-set_io_pin_constraint -region left:* -pin_names [match_pins {(R|W)[0-9]+_.*}]
+# By placing the pins at the left edge, then by mirroring on
+# X and Y, it is possible to place the pins in 4 significantly
+# different orientations. In lieu of being able to rotate a
+# macro 90 degrees, this is a good compromise.
+set db [::ord::get_db]
+set block [[$db getChip] getBlock]
+set die_bbox [$block getCoreArea]
+set dbu_per_uu [expr double([[$db getTech] getDbUnitsPerMicron])]
+set scale [expr 1 / $dbu_per_uu]
+#puts $f "width: [expr [$die_bbox xMax] * $scale]"
+#puts $f "height: [expr [$die_bbox yMax] * $scale]"
+set height [expr [$die_bbox yMax] * $scale]
+set width [expr [$die_bbox xMax] * $scale]
+
+set tech [$block getTech]
+if {$height > $width} {
+  set layer [$tech findLayer $::env(IO_PLACER_V)]
+  set pitch [expr [$layer getPitchX] * $scale]
+  set edge_length $height
+  set edge left
+} else {
+  set layer [$tech findLayer $::env(IO_PLACER_H)]
+  set pitch [expr [$layer getPitchY] * $scale]
+  set edge_length $width
+  set edge top
+}
+set pin_names [match_pins {(R|W)[0-9]+_.*}]
+
+set_io_pin_constraint -region $edge:0-[expr min($edge_length, $pitch * ([llength $pin_names] + 4) * 1.3)] -pin_names $pin_names