Systems Reference Library - All about the IBM 1130 Computing ...

Digital InputDigital input features enable the processor-controller(P-C) to accept real-time digital informationin a digital format. The modular design of thefeatures permit individual system tailoring forspecific types and quantities of digital input data,such as:Contact sense. Mechanical counters.Voltage level sense. Electronic counters.Contact interrupt. Rotary switches fromVoltage level interrupt. operator panels.Digital voltmeters. Sense switches fromSpecial analog-to- operator panels.digital converters. Pulse tachometers.Turbine flowmeters. Frequency meters.Shaft encoders. Watt-hour meters.Electronic registers, Vibration detectors.including telemetry. Weighing devices.Digital input is brought into the system in 16-bit groups. The format may be in any form. Forexample :Unrelated bits from contact or voltage levels.Binary numbers.Binary-coded-decimal digits.Decimal digits.Gray code digits.Any mixture of digital formats can be handled.Conversion from one base to another can be easilyand quickly implemented by the program. Data inputis under direct program control or data channelcontrol. In direct program control, one instructionis used to bring 16 bits of data into core storage.With a data channel, one instruction initiates anoperation that brings many 16-bit groups of datainto core storage (one group per core storage cycle).The number of groups read (sequentially, randomly,or single address) and synchronization of the P-C tothe input data are handled automatically.Interrupt conditions from the process are a typeof digital input. These process interrupts arebrought into the P-C in 16-bit groups, with up tofour priority levels of interrupt and four interruptconditions per level for each 16-bit group.High-speed 8-bit or 16-bit binary electronicpulse counters are available as special features.Counters are read into core storage as digital inputgroups, 16 bits at a time (two 8-bit counters or one16-bit counter).As shown in Figure 44, the combined capacity ofthe digital input and pulse counter features is 1,024bits, as follows:Digital Input8 adapter x 8 digital input groupsx 16 bits per group = 1,024.Pulse Counter8 adapter x 128 pulse counter bitsper adapter (pulse counters can be8-bit or 16-bit counters) = 1,024.Any combination of these adapters, digital inputgroups, and pulse counters may be used within thecapacity of 1,024 bits.The capacity of the process interrupt feature is24 priority levels or 384 bits, as follows:8 adapter x 3 process interrupt groups(24 levels)x 16 bits per group = 384Control for digital input features is provided bydigital input basic, which is supplied with the basicP-C. Digital input basic provides timing control,checking control, and an interface to the P-C for alldigital input features.The 1826 Data Adapter Unit provides housing fordigital input points. The following units and featuresmay be added to the system to provide digital inputfunctions. For specifications, see 1800 InstallationManual - Physical Planning, Order No. GA26-5922.DATA CHANNEL ADAPTERThis feature adapts digital input basic to a datachannel and provides the controls necessary toenable digital input via data channel (cycle steal)operations. A word counter and scan control114