greg@ncelvax.UUCP (Gregory K. Ramsey) (07/08/89)
Can anyone tell me, is there an ANSI (or other) standard that
corresponds to the VT100 or VT220 terminals? or would it be
more appropriate to ask if the VT100/220 properly emaulates
some standard.
My VT220 quick referance book says something about an ANSI
mode for the VT100 & 220 but that implies we might be losing
some of the terminals functionality when doing that.
I need this information asap so an Email reply would be
greatly appreciated.
Greg
greg@ncelvax.uucp or
ncelvax!greg@nosc.mil or last choice
gkr@nosc.mil
--
___ Greg Ramsey
_n_n_n____i_i ________ Naval Civil Engineering Lab
(____________I I______I Code L54 805/
/ooOOOO OOOOoo oo oooo Port Hueneme, CA 93043 982-4619leichter@CS.YALE.EDU (Jerry Leichter) (07/08/89)
In article <430@ncelvax.UUCP>, greg@ncelvax.UUCP (Gregory K. Ramsey) writes... >Can anyone tell me, is there an ANSI (or other) standard that >corresponds to the VT100 or VT220 terminals? or would it be >more appropriate to ask if the VT100/220 properly emaulates >some standard. > >My VT220 quick referance book says something about an ANSI >mode for the VT100 & 220 but that implies we might be losing >some of the terminals functionality when doing that. > The relevant ANSI standard here, if I remember right, is ANSI X.34. All DEC terminals since the VT100 have complied with this standard. However, it's important to realize what "compliance" means. ANSI X.34 specifies a couple of things: - The syntax for various kinds of command sequences - that's where all the ESCAPE [ stuff comes from, there is a defined class of command sequences, called control sequences, which have the syntax ESC [ <par> <int> <fin>, where <par>, <int> and <fin> are mutually exclusive sets of characters. There are something like five classes of command sequences; they are almost identical in syntax, with the exception of their initial two characters. - A set of functions, and command sequences to invoke them. A termi- nal need not implement all the functions - I'm not sure if ANY are considered mandatory - but if it DOES implement a function, it must implement it exactly as specified, and invoke it using the specified command sequence. No DEC terminal implements all of the specified functions, though recent ones implement most of them. (Most of the ones that have been left out have to do with block mode; X.34 specifies a large and complex block mode.) I know of no terminal which implements everything in X.34. - A set of internal states, which influence the behavior of some of the defined functions, and a set of command sequences to let you change the states. In some sense, any X.34 terminal must implement all the states, though it may declare some of them as permanently set or reset. (Of course, if the terminal implements no function which depends on some state, there is no way you could ever tell if it was set or reset....) Again, no DEC terminal - and no terminal I know of - actually implements as "live" all the specified states, though most of the omitted ones have to do with details of the X.34 block mode model. - A set of reserved command sequences. This set includes all the command sequences to which X.34 assigns a meaning, and a whole bunch more besides. (You can view those as defined to be no-ops in the current version of the spec.) The basic rule is that a terminal must implement a reserved command sequence either exactly as specified by X.34, or as a no-op. - A set of extension command sequences. These can be defined by a given vendor any way he likes. Note that the syntax must remain compliant with the ANSI syntax spec; it's the semantics which a vendor is free to specify. The simplest way to determine which of the VTxxx commands are ANSI and which are DEC extensions is to look at the names: X.34 specifies standard names for its commands, such as CUP (Cursor Up) for ESC [ <x> A. DEC's names always start with DEC - I think DECSTBM (Set Top and Bottom Margin, which specifies the scrolling region), ESC [ <t> ; <b> r is an example. In the case of mode settings, the commands are fixed but the DEC mode names start with DEC. "ANSI mode" on a VT100 or later DEC terminal is identical to VT100 or VT200 or VT300 mode. It is being distinguished, not from some DEC extended mode, but from the VT52 emulation mode these terminals support. -- Jerry