add 6600 page

diff --git a/3d_gpu/6600scoreboard.mdwn b/3d_gpu/6600scoreboard.mdwn
index 96523f33f570057ed50930072f3977e88bb8c00d..9c859d8ba0de7067a73589d9f99367abf4369993 100644 (file)
--- a/3d_gpu/6600scoreboard.mdwn
+++ b/3d_gpu/6600scoreboard.mdwn
@@ -13,7 +13,12 @@ However the same thing has to be done for the read path, as well.
 
 Below are the modifications required to add a read-release path that
 will prevent a Function Unit from requesting a GoRead signal when it
-has no need to read registers.
+has no need to read registers.  Note that once both the Busy and GoRead
+signals combined are dropped, the ReadRelease is dropped.
+
+Note that this is a loop: GoRead (ANDed with Busy) goes through
+to the priority picker, which generates GoRead, so it is critical
+(in a modern design) to use a clock-sync'd latch in this path.
 
 [[!img comp_unit_req_rel.jpg]]
 [[!img group_pick_rd_rel.jpg]]