twh@mb2c.UUCP (Tim Hitchcock) (04/26/85)
Will the 4420 terminal use tabs properly with termcap functions. It seems that the hardware tabs are set up correctly (NOT every 8 spaces, little dots identify), but when I try to input data, the tabs come out every 8 spaces anyway. I realize that the 4420 does not use the forward tab key, so I am talking control I. Is it considered bad practice to write termcap systems to run on the 4420 ? Thanks
wcs@ho95b.UUCP (Bill Stewart) (04/29/85)
Tim Hitchcock at Michigan Bell asked about using tabs with the AT&T 4420, especially with termcap. > Will the 4420 terminal use tabs properly with termcap functions? > It seems that the hardware tabs are set up correctly > (NOT every 8 spaces, little dots identify), but when I try to input > data, the tabs come out every 8 spaces anyway. > I realize that the 4420 does not use the forward tab key, > so I am talking control I. Is it considered bad practice to write > termcap systems to run on the 4420 ? I haven't seen the 4420; (I assume it's like the AT&T Teletype 5425?). The normal working environment for UNIX is a full-duplex asynchronous terminal - you type the character on the keyboard, the terminal sends it to the computer, and the computer decides what to do with it. For normal activity, the computer echoes the character back to your terminal; in most termcap applications the program controls what to send back to your terminal, such as echoing the character or erasing hunks of stuff off your screen. Even in normal "cooked" mode, though, TAB is a special character. The normal meaning for tabs in the UNIX environment is every-8-spaces. Many programs have this meaning wired into the code, because it's a standard, and because it's easy to code. The terminal driver software is commonly set to translate tab characters on output to next-8-space-tabstop. The "stty" command has a "tabs" option which allows genuine tabs to reach your terminal; this can improve speed, but it's only safe to use if your terminal has the tabs set in the right places, i.e. 1,9,17,... As for "not using the forward tab key", the forward tab on almost any terminal I've used (including the AT&T 4410 and 4415) transmits a Control-I. I doubt they've done something radically stupid with it, although I suppose they might provide some LOCAL/TRANSMIT option setting? (Televideo did this with the backspace key on the 950. DUMB!) BACK-TAB characters, on the other hand, are different on each model of terminal, and are unlikely to be interpreted correctly on UNIX. Bill Stewart, AT&T Bell Labs, Holmdel NJ -- Bill Stewart 1-201-949-0705 AT&T Bell Labs, Room 4K-435, Holmdel NJ {ihnp4,allegra,cbosgd,vax135}!ho95c!wcs
ped@mtuxo.UUCP (p.davidson) (05/02/85)
REFERENCES: <154@atvax.UUCP>, <2655@drutx.UUCP> Just as a point of interested the 4420/5420 Has been replaced with the 5425/4425