Now, your HP-41 hand-held computer can easily communicate with, and control, any Hewlett-Packard Interface Loop (HP-IL) peripheral. Present HP-IL peripherals include a printer, a digital cassette drive, a converter, and a digital multimeter. But that's not all. A video interface has been announced but will not be available until later this year. Also, with the new HP82938A Series 80 HP-IL Interface Card, your HP Series 80 Personal Computer can interact with your HP-41 through HP-IL, and it can act as a controller of the HP-IL loop. And, with the addition of the new HP82182A Time Module, your HP-41 becomes a care-free, time-based controller. Ah, but this is jumping ahead; let's discuss the fundamentals.
The HP-IL concept revolves around a two-wire cable that can connect as many as 30 HP-IL devices in a closed series loop. HP-IL is a "master-slave" interface, meaning that one active controller regulates the information flow between all of the devices in the loop. Data and commands move around the loop in one direction.
The reason we use such terms as "the controller" and "a device" is because HP-IL is a general-purpose interface. The elements of the system that you choose to use will be tailored specifically to your application. This is the flexability of the HP-IL concept.
At the core of this new concept is the new HP82160A HP-IL Module. This module fits into any of the four HP-41 ports, and it expands the HP-41 with a powerful set of functions for interaction with the devices in the loop. Now, printers, mass-storage devices, and a variety of instruments can be controlled by the HP-41 through one port!
A general application of such an HP-IL system would use the new HP82182 Time Module, which is discussed in the following article, to "wake up" the HP-41 in the middle of the night, while you are at home sleeping. Automatically, then, the HP-41 would begin to execute a control program. HP-IL allows you to program the HP-41 to power-up devices in the loop, take readings from instruments, make data listings, read subprograms from mass storage devices, and interact with other devices in the loop as prescribed by the programs. The extensive programming capabilities of the HP-41 allow it to make critical decisions based on the data received from the instruments in the loop and interact with other devices in the loop, accordingly. Then, with its job complete, the HP-41 can power-down the devices in the loop, including itself. When you arrive at work in the morning, after a good night's rest, a printer listing awaits you, documenting the events of the night as monitored by the HP-41!
And, this is only the beginning. Hewlett-Packard is committed to continuing its quality support of HP-IL. The devices that are compatible with the HP-41 as a mainframe controller will be compatible with future hand-held computers and personal computers with input/output capabilities. Many HP divisions - in the instrument and computer areas - will be introducing HP-IL devices.
We have enough space to give you only a small taste of the broad capabilities of HP-IL. See your local HP Dealer for a look at the new HP-IL system, and see if it will meet your challenge; we'll bet it can - and does!
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