Vandling / Global NDB-2 aircraft navigation unit teardown

More aircraft avionics to take a look at again. This time we have a Global NDB-2 which is an optional unit for the GNS-500A navigation system commonly fitted to private business jets. This unit is a “databank” containing coordinates and other information for over 20,000 airports and airfields worldwide. It consists of a main unit and a removable memory unit which can also be upgraded via floppy disks. Yeah this thing is old – dates from the early 1980’s.

The memory unit contains a Z80 CPU with an EPROM containing the firmware, 64Kb of RAM and 256KB of battery backed SRAM for storing the database. The main unit consists of 2x ARINC-429 interface boards, a CPU board and a DC-DC converter. The CPU board is powered by a Motorola 6809 CPU and has three RS422 interfaces, two of which go to the rear panel and the other to one of the ARINC boards.

I also dumped the EPROMS and ran them through a disassembler to get Z80 and 68xx assembly code. They can be downloaded here.

Photos of the boards


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