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
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    It might be useful to narrow this a bit down, after all, MS-DOS has been delivered in many versions over 20+ years. Finding some utility (toward the end) having it used is inevitable. – Raffzahn Aug 24 at 9:52
  • yeah, but it's old and I shall let it be. – KlaymenDK Aug 24 at 14:30

Since the asker mentioned ‘similar executables’, I think it is fair to mention Microsoft Diagnostics, a utility bundled with MS-DOS 6.22 (at least; probably with some other versions too), which displays this message upon startup:

MSD is examining your system...

One may argue that MSD shouldn’t count as ‘MS-DOS itself’, because it isn’t part of the ‘core’ MS-DOS; that, however, may be countered by saying that what deserves to be called a ‘core’ program is very much subjective anyway. The asker apparently considers FORMAT.COM a core utility, but it is very much possible to use DOS without formatting any disks; it isn’t strictly necessary. Not even COMMAND.COM is technically necessary to use DOS; a SHELL= setting in CONFIG.SYS can change the first loaded program to any other executable, not even necessarily an actual shell. MSD is located on the second of the three MS-DOS 6.22 installation floppies, and the setup program will install it by default, so it can be considered just as much a part of the operating system as HIMEM.SYS.

Another example is FDISK, which displays a blinking warning at the partition deletion prompt:

WARNING! Data in the deleted Primary DOS Partition will be lost.

Yet another is VSAFE, an anti-virus TSR licensed by Microsoft from Central Point Software, distributed with MS-DOS 6.22:

VSafe Warning: Program is trying to write to Hard disk. Do you wish to continue?

Those are the only examples that I know of. Blinking text was not frequently used perhaps less because it was considered ‘over the top’, but rather because most DOS applications were written against the terminal-style interrupt 0x21 I/O services, which did not expose capabilities like blinking text that are specific to PC video hardware. In return, those programs were able to be used with any terminal device that had DOS drivers; one could for example invoke the CTTY AUX command and later be able to interact with programs like FORMAT via a serial connection. TUI-style programs that accessed video hardware directly or via interrupt 0x10 calls (necessary to output blinking text) did not have this capability. But even the relatively few programs in the latter group usually had no reasonable use for blinking text.

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    Good points, I have changed my answer based on your mention of FDISK. – KlaymenDK Aug 24 at 8:54

[...] 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
  • edit came rather late to the game - MS-DOS 5.0 - replacing edlin (most likely because OS/2 and NT needed a more intuitive editor). edlin could - like ed on unix systems - be used with a very dumb terminal. – Thorbjørn Ravn Andersen Aug 22 at 23:34

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