Asynchronous Serial Communications Programmer's Reference Manual (32022-90052)

286 AppendixA

Comparing MPE/iX Systems to MPE V Systems

Physical Appearance

The most apparent change when migrating from MPE V to MPE/iX is

the hardware conﬁguration. The ATP/ADCC interface cards are placed

directly in the SPU of MPE V computers. Therefore, the RS-232/422

cabling for asynchronous devices connects directly into the system

cabinet. In comparison, MPE/iX computers use DTCs

(Datacommunications and Terminal Controllers) connected as nodes on

a LAN. The interface cards to which the cables of devices are connected

reside in the DTC. To communicate with asynchronous devices, the

SPU must hold only the interface card for the LAN.

Although the physical environment of the subsystem on MPE/iX

computers looks very different from that of MPE V computers, the

resultant functions and characteristics of the subsystem software are

very similar. In fact, as long as an asynchronous device is supported on

both systems, very little difference should exist between using the

device on an MPE V computer and using it on an MPE/iX computer.