akcs.macrokid@hpcvbbs.UUCP (Kevin Vashi) (03/16/91)
Hello,
I have a couple of questions about the I/O interface on the
HP-48SX.
1) Is the signal from the HP-48SX a true RS-232 signal.
From an interface posted by somebody from UK (Can't remember the name)
it seem like that the HP signal is half of RS-232 signal but it occurs
twice as many times.
eq: ---- --------
----| |--| |------ <--- RS-232 output.
-- -- --
______| |___| |_| |_____ <--- HP Output.
2) What is the difference between half duplex (as used on HP) and
full duplex.
Any relevent information will be greatly appreciated.
Thank You,
KLevin Vashi. INTERNET: eaeu147@orion.uci.edu.
Kevin Vashi. bgribble@jarthur.Claremont.EDU (Bill Gribble) (03/16/91)
In article <27e112ba:2441comp.sys.handhelds@hpcvbbs.UUCP> akcs.macrokid@hpcvbbs.UUCP (Kevin Vashi) writes: >Hello, > I have a couple of questions about the I/O interface on the >HP-48SX. > 1) Is the signal from the HP-48SX a true RS-232 signal. > From an interface posted by somebody from UK (Can't remember the name) > it seem like that the HP signal is half of RS-232 signal but it occurs > twice as many times. > eq: ---- -------- > ----| |--| |------ <--- RS-232 output. > > -- -- -- > ______| |___| |_| |_____ <--- HP Output. You might want to ask HP for their IO Tech. Interfacing document. Just reply to the message on hpcvbbs (I think in the feedbackto.hp conference, but I'm not sure) and HP will send you one. It's not really that useful (I was looking for info on how the interrupt handler and serial buffer work) but does have timing diagrams and the sort of information you are looking for. Getting mine out, I quote: [w/o permission] "The serial I/O port is a full-duplex UART with RS-232 compatible signal level shifting." I think this answers both your questions. The 48's output timing is just like rs-232. >Kevin Vashi. ***************************************************************************** ** Bill Gribble Harvey Mudd College, Claremont, CA ** ** bgribble@jarthur.claremont.edu Never heard of it? You're stupid. ** *****************************************************************************