jakimik@uwvax.UUCP (06/14/83)
Do not get an Apple //e if you value a good keyboard! It is advertised as having N-key rollover, but it doesn't. So if you are a touch typist, like me, the keyboard will get confused at times and send out bad characters. Below I will type "temp". (I am typing on a //e.) temp tevmp temp temp tevmp temvp temp tevmp temp tmevp tevmp tevmp tevmp If you press "t", then "e" (while keeping "t" down), then "m" (while keeping "te" down) a "v" decides to join in for the fun. -David Neves
tbm@hocda.UUCP (06/15/83)
EERRrrr, Re the Apple //e keyboard. Advice is worth what you pay for it. As usual I have a friend who was a state champion typist contender. He earned his was through school by typing. (Something like $5 per page after 3am) He could not be happier with the //e. The thing is he never heard of "N key rollover"~r~r. Tom Merrick BTL MV
cfv@packet.UUCP (06/15/83)
Sounds like Apple used the same keyboard as the new Z29 terminal. Same N-key
terminal, same glitchy system. try typing 'list' on a Z29, and it will almost
always add a 'q' to it somewhere...
--
>From the dungeon of: Chuck Von Rospach
ucbvax!amd70!packet!cfv
(chuqui@mit-mc) <- obsolete!ron%brl-bmd@sri-unix.UUCP (06/16/83)
From: Ron Natalie <ron@brl-bmd> Obviously the N-key roller on the Apple //e has N set to 1. -Ron
jed@mb2c.UUCP (06/17/83)
The most recent CALL-A.P.P.L.E. has a good comparison between the II and the //e and refers to the N-key rollover of the older Apple-II and II+ machines. I own a Rev-1 Apple-II and can attest to the frustration of depressing 3 keys and getting a fourth at no extra charge. To quote from the article: ...I also discovered that the electronics of the keyboard has been cleaned up. On the old system I used my standard habit or rolling my fingers across ASDF to produce a test string. Being fast in this process, I always got ASDF2, that is no longer true. In fact, the //e has the true N key rollover feature, e.g., if you are fast enough and have enough fingers you can press and hold down the A key, then press and hold down the B key, etc. No matter how many keys you hold down, you always get the last key you hold down... Not owning one, I can't personally attest to the quality of the rollover, but it sounds good to me. John Duncan (mb2c!jed) Michigan Bell (313) 424-0711
MCMANIS%usc-eclc@sri-unix.UUCP (06/20/83)
From: Chuck McManis <MCMANIS@usc-eclc> I just finished building a H-29 and have had no problems. I have even tried pressing 4,5, and 6 letter groups at the same time for increased if not unreasonable speed, and have yet to see it type a character that was not part of the group. Maybe your keyboard controller (it uses an 8021) is defective? --Chuck -------
darrelj@sdcrdcf.UUCP (06/26/83)
Part of a full N-key rollover keyboard implementation requires that the connection made in the scanning matrix (typical scanning chips have the potential for somewhere between 70 and 110 keys in a not too far from square array, e.g. 8x11) have a nonzero connection impedence under some characteristics. The possibilities include plain (0 ohm) switches with diodes (so switch is unidirectional) and switches which create a resistor or capacitor with measurable impedance, thus sneak paths have at least 3X the impedance, so a carefully tuned threshold detector won't see false keys. Another approach in some Hall-effect keyboards (in which each key contains a little detector chip) is that the key sends simultaneous brief pulses onto it's two lines in the scanning matrix on key closure. Ghosts then can occur only in the event two keys are pressed in one pulse time (less than a millisecond, usually).