From 36d0c8bc6247b46d6fe7bd2f5ea1f39898047b8b Mon Sep 17 00:00:00 2001
From: akuker <34318535+akuker@users.noreply.github.com>
Date: Mon, 4 Jan 2021 15:50:57 -0600
Subject: [PATCH] Updated Dayna Port Command Set (markdown)

---
 Dayna-Port-Command-Set.md | 22 +++++++++++++++++++++-
 1 file changed, 21 insertions(+), 1 deletion(-)

diff --git a/Dayna-Port-Command-Set.md b/Dayna-Port-Command-Set.md
index 117cd30..88a6eac 100644
--- a/Dayna-Port-Command-Set.md
+++ b/Dayna-Port-Command-Set.md
@@ -42,7 +42,27 @@ Type:     Input (Transitions to DATAOUT)
 
 Host then sends: `00 09 00 07 FF FF FF 00` (The last 00 might not actually be there?)
 
-Note: The AppleTalk broadcast address is 09:00:07:ff:ff:ff. So this command probably has something to do with setting up AppleTalk?
+Note: The AppleTalk broadcast address is 09:00:07:ff:ff:ff.
+
+This is probably configuring the Multicast Address Registers of the [DP83902A Ethernet receiver](./docs/DP83902A.pdf) inside the DaynaPort SCSI Link
+
+    10.9 MULTICAST ADDRESS REGISTERS (MAR0 –MAR7)
+    
+    The multicast address registers provide filtering of multicast 
+    addresses hashed by the CRC logic. All destination addresses 
+    are fed through the CRC logic and as the last bit of the 
+    destination address enters the CRC, the 6 most significant bits 
+    of the CRC generator are latched. These 6 bits are then decoded 
+    by a 1 of 64 decode to index a unique filter bit (FB0 –63) in 
+    the multicast address registers. If the filter bit selected is 
+    set, the multicast packet is accepted. The system designer 
+    would use a program to determine which filter bits to set in 
+    the multicast registers. All multicast filter bits that 
+    correspond to multicast address accepted by the node are then 
+    set to one. To accept all multicast packets all of the 
+    registers are set to all ones.
+
+
 
 ## Enable/disable Interface (0e)
 Command:  0e 00 00 00 00 XX (XX = 80 or 00)