Early Dumb terminals were inexpensive devices but very slow compared to punched cards or paper tape for input, yet as the technology improved and video displays were introduced, Dumb terminals pushed these older forms of interaction from the industry.
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Great majority of Dumb terminals were monochrome, manufacturers variously offering green, white or amber and sometimes blue screen phosphors.
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Some dumb terminals had been able to respond to a few escape sequences without needing microprocessors: they used multiple printed circuit boards with many integrated circuits; the single factor that classed a terminal as "intelligent" was its ability to process user-input within the terminal—not interrupting the main computer at each keystroke—and send a block of data at a time .
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Around the mid 1980s most intelligent terminals, costing less than most dumb terminals would have a few years earlier, could provide enough user-friendly local editing of data and send the completed form to the main computer.
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The VT100, Heathkit H19 in ANSI mode, Televideo 970, Data General D460, and Qume QVT-108 Dumb terminals all followed the ANSI standard, yet differences might exist in codes from function keys, what character attributes were available, block-sending of fields within forms, "foreign" character facilities, and handling of printers connected to the back of the screen.
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Smart or intelligent Dumb terminals are those that have the ability to process escape sequences, in particular the VT52, VT100 or ANSI escape sequences.
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The electronic demands of refreshing display memory meant that graphic Dumb terminals were developed much later than text Dumb terminals, and initially cost much more.
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Some block-mode Dumb terminals have both an ? Enter and local cursor moving keys such as Return and New Line.
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In contrast, IBM 3270 Dumb terminals connected to MVS systems are always required to be in block mode.
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Subsequent "smart" or "intelligent" Dumb terminals incorporated microprocessors and supported more local processing.
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Programmers of block-oriented Dumb terminals often used the technique of storing context information for the transaction in progress on the screen, possibly in a hidden field, rather than depending on a running program to keep track of status.
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