SCHOMAKE@HNYKUN53.BITNET (09/25/86)
(BTW, no news on Mumps? My-mail: Tue 2 Sep 86 08:22:52-PDT
Subject: MicroMumps for the ST? )
I -Digitizers for the ST?-
As many may have noticed, a mouse is a very handy instrument for walking
through menus, creating rectangular boxes etc. For entering subtle graphics
it is awkward. Just try to enter your signature with a mouse (....).
The difficulty is caused by the orientation sensitivity and scaling problems
of the mouse and the fact that we use the fine musculature of the hand in
normal writing and drawing. Therefore we are searching a digitizer tablet for
the ST in our project on handwriting recognition and -simulation.
A 1040 ST could become a graphics workstation, connected to a VAX via the
serial interface.
II -Ports-
As I can think of, there are 3 possibilities:
(a) replacing the mouse by a tablet (this demands dedicated hardware).
(b) connecting a digitizer to the DMA interface (dedicated hardware).
(c) connecting a digitizer to an RS-232 interface (general solution).
Although we prefer solution (c), we want the workstation to be connected to
the VAX all the time: so we would need a second RS-232 interface for the
ST in that case.
III -Sampling-
Another problem we have is the tablet sampling frequency. This frequency
should be adjustable from 100 Hz (min.) to 200 Hz or up. Also, the tablet
should *not* have any intelligence since we want to make a time record of
the displacements of the pen tip.
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Any information on this subject (hardware/software) is welcome!
We would like to convince our officialdom that the word *ATARI*
is no Japanese for "Video Freak Toys Only".
*
^^^^^
KKKKKUUUUNNNNN
KKK UUUU NNNN Lambert Schomaker
K UUUU NNN SCHOMAKER@HNYKUN53.BITNET
KKK UUUU NN Nijmegen, The Netherlands.
KKKKK UU Nbammi@case.CSNET ("Jwahar R. Bammi") (09/28/86)
> As I can think of, there are 3 possibilities: > > (a) replacing the mouse by a tablet (this demands dedicated hardware). > (b) connecting a digitizer to the DMA interface (dedicated hardware). > (c) connecting a digitizer to an RS-232 interface (general solution). > > Although we prefer solution (c), we want the workstation to be connected to > the VAX all the time: so we would need a second RS-232 interface for the > ST in that case. > >III -Sampling- > > Another problem we have is the tablet sampling frequency. This frequency > should be adjustable from 100 Hz (min.) to 200 Hz or up. Also, the tablet > should *not* have any intelligence since we want to make a time record of > the displacements of the pen tip. After a couple of moments of thought, i would say why not use the printer port. Think of the printer port as a parallel Input port with one interrupt input - the strobe. I would put the serial output of the tablet, through a Usart, to the parallel input port. The data ready strobe of the usart would drive the interrupt (strobe) input. The power for the usart can be tapped off the joystick port. Then all that is left to do is to write an interrupt routine to handle the strobes. There is interrupt reserved for centronics strobe, that is routed through the MFP and the 68000 see it at IPL6. So your sampling frequency is only limited by how fast you can process the interrupt. By putting the usart, you have effectively a 8 bit buffer, so the sampling rate requirement should go down quite a bit, as now you are going to sample 8 bits at a time. This should work pretty good with tablets like the Summargraphics, which i seem to recall, send out data as 2 4 bit packets in any case (at least that is true in one of the modes), which the usart will latch and pass on. I know its easier said than done, but its another idea off the top of my head. Hope it helps some. usenet: .....!decvax!cwruecmp!bammi jwahar r. bammi csnet: bammi@case arpa: bammi%case@csnet-relay compuServe: 71515,155