Block Multiplexer and Byte Channel Modules allowed direct connection of high speed disk / tape systems, and low speed printers, etc . respectively.
2.
The 3830-2 connects to one, two or four block multiplexer channels and can attach any combination of up to four A-units, i . e ., any combination of 3350-A2 / A2Fs up to a maximum of 32 physical drives ( up to 6 additional drives attached to each A-unit ).