I know that it was possible to create blinking text, but did the operating system itself (I mean, in output from functions of command.com and similar executables) ever make use of blink formatting?

You'd think it would be useful for confirmations of really dangerous things like format C: and such, but perhaps also seen as "over the top" and or just not necessary.

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    It obvioulsly used a blinking cursor - That was about the amount of blinking the OS used. – tofro Apr 18 '19 at 7:42
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    I thought the blinking cursor was a hardware function, not operating system, but I might be wrong. – manassehkatz-Moving 2 Codidact Apr 18 '19 at 15:07
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    @manassehkatz see this question. – Stephen Kitt Apr 18 '19 at 17:05

[...] did the operating system itself [...] ever make use of blink formatting?


MS-DOS was, at the core, machine agnostic. It only used the most basic features provided by the BIOS. While INT 10h function 09h would have provided the ability to set attributes (via BL), its meaning already varies across video cards offered by IBM and even more so with third party cards or non IBM machines. Not to mention that MS-DOS was intended to work with terminals as well, where attributes are even more diverse.

MS-DOS only used the most basic characters for output control:

  • CR
  • LF
  • FF (clear screen)
  • BEL
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    MS-DOS 2.0 to 5.x included a driver called ANSI.SYS which provided support for escape codes to control character attributes; I'm pretty certain escape-leftbracket-5m was supported as a means of enabling blinking, along with ...[1m for bright text, ...[30m to ...[37m for foreground color, etc. – supercat Apr 17 '19 at 21:41
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    @supercat Jup, another optional add-on, nothing a cor OS can rely on. – Raffzahn Apr 17 '19 at 22:08
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    @Raffzahn however COMMAND.COM does check for ANSI.SYS and will use it if it’s available, e.g. for CLS. – Stephen Kitt Apr 18 '19 at 11:35
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    Can't imagine that working well with an actual printer, either. – Lightness Races in Orbit Apr 18 '19 at 17:20

Did MS DOS itself ever use blinking text?

What exactly does "itself" mean?

The OS kernel (io.sys or msdos.sys) would of course not do anything which is not requested by the currently running program (e.g. command.com); the kernel cannot know if some text message has the meaning: "Highly critical" or "Operation successful" so the request to change the text attributes must come from the program.

In MS-DOS consists of multiple programs. Most of them just wrote out text to the console while the text cursor was only moved implicitly because of printing the text.

However, there were also some "GUI-like" programs (fdisk, edit, GW or Q Basic, scandisk, the DOS-Shell and some backup program) being part of MS-DOS, which modified the content of the the entire text screen and explicitly moved the text cursor to certain positions.

As far as I know, the first type of programs (only printing text) never changed the text attributes. Neither color, nor blinking, nor bold. If the user selected blinking green text on blue background using ansi.sys (see supercat's comment), all of these programs would output all text green and blinking on blue background. If the user did not use ansi.sys, all text was gray, not blinking on black background.

The "GUI-like" programs used different screen attributes (such as different colors, bold or blinking). fdisk for example used bold text; edit used different colors. I'm not sure if one of these programs used blinking text.

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    I have vague recollections of an MS-DOS pack-in program (it could have even been fdisk) that did use blinking text as a warning to the user before erasing all data on-disk. – Dai Apr 18 '19 at 14:26
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    I have similar very vague recollections, but that it was one of the OEM-added programs, possibly fxpark or fxprep. – JdeBP Apr 18 '19 at 17:57

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