Just some rough infos regarding APG40C and IOG20C:
APG40C – I/O device introduced with AXE810 (new HW based on BYB501 building practice); faster than IOG20C; mandatory in some cases
IOG20C – older type of I/O device; slower than APG40C, but for regular exchange more than enough; supports X.25, FR, which are not supported with APG40C
Regards
Ivan