The ALHAMBRA Central Heating Controls

Press ADVANCE to start. See bottom of page for questions and explanation of what it's about.

ON: OFF:

Summary Instructions

These controls determine three periods of heating for each weekday. By clicking the ADVANCE button you can move from day to day and within each day you can move through the ON and OFF times for each period. The PLUS and MINUS buttons alter whichever panel is currently highlighted. Don't try typing in the boxes - just use the PLUS and MINUS buttons.

 

When the day of the week is highlighted, PLUS moves on to the next day, and ADVANCE brings up the settings for the day, while you can use the COPY button to copy yesterday's settings to today.

Manufacturer's Instructions

How to check your programming:

press the 'show events' button. NOTE that this is not part of the original device.

Questions

    1. Which of the 5 generic activities best describes typical interaction with a central heating controller?
    2. What is the notation of the main device?
    3. How does this controller rate on the dmensions of viscosity and abstraction level? (Compare it to the Balmoral model.)
    4. What abstractions are available? are they transient or persistent? is there an abstraction management sub-device?
    5. How does it rate on visibility and hidden dependencies? Compare it to the Chateau model.
    6. How does it rate on closeness of mapping, compared to the Chateau model?

"What's all this about?"

I have set up this virtual device, and a number of others, to illustrate the 'Cognitive Dimensions' framework. (If you don't know about the framework, you can look at a brief introduction or a full-length tutorial.) By comparing alternative designs for the same purpose, you can see how the framework helps to understand the pros and cons.

At present there are other examples of heating controllers, an example of a telephone (more to come), and two examples of menu selection.A three-button watch and a two-button pager are nearly finished.

Some of these devices may raise usability issues that go beyond the cognitive dimensions framework. For really keen head-scratchers, look also at Ontological Sketch Models (somewhere on my work pages). The Cognitive Walkthrough is an alternative evaluation method, or, coming from a different direction, try Thimbleby's state-space analysis.

The original device is the Horstmann ChannelPlus H17 manufactured by Horstmann Timers and Controls Ltd, Newbridge Rd, Bath BA1 3EF, UK. (Photograph to come.)

Thomas Green; home page

December 1999