IBM 520 User Handbook Manual page 164

10BaseT
Net 1
HUB 1
10BaseT
HUB 2
Net 1
Port 1 Port 2 Port 3 Port 4
Port 1
Port 2
Port 3
Port 4
Net 1
10BaseT
HUB 3
10BaseT
Net 1
HUB 4
Router
Protocol Protocol
Virtual Network Layer
LAN Driver
LAN Driver
Port 4 Port 3 Port 2 Port 1
Adapter 1
Adapter 2
VNET
Switch
1
System Bus
10BaseT
Net 2
HUB 5
10BaseT
HUB 6
Net 3
Port 1
Port 2
Port 3
Port 4
Net 4
10BaseT 10BaseT
Net 5
HUB 8 HUB 7