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Path: news.uiowa.edu!chi-news.cic.net!hookup!news.mathworks.com!tank.news.pipex.net!pipex!blackbush.xlink.net!ka.sub.net!news From: Oliver.Schmidt@powerframe.de (Oliver Schmidt) Newsgroups: comp.sys.apple2 Subject: Re: Apple Graphics Tablet Date: Wed, 12 Jun 1996 08:25:43 GMT Organization: powerframe Datensysteme GmbH Lines: 77 Message-ID: <4pluvs$mh8@ka.sub.net> References: <255967003.15208359@adbbs.antioch.edu> NNTP-Posting-Host: pcos.pf.sub.de Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit X-Newsreader: Forte Free Agent 1.0.82 John_L._Graham@adbbs.antioch.edu (John L. Graham) wrote: >I had a similar question. I recently was given an Apple Graphics Tablet in >_mint_ condition. Interface card and everything, but no software. Does anyone >know how to write programs which can use it? I looked in our library of Apple >tech notes but came up empty. Hi, first, let's make sure we're talking about the same thing: the Apple Graphics Tablet I know of is rather large and heavy; its pen is attached to it with a (too short) cable; it makes funny sounds that change when the pen is moved in/out the reach of of the tablet. A long time ago I patched a few programs to make use of this tablet. To make it clear in the first place - I don't have theese patched versions available anymore :-(. But I found a listing from which I can tell You this: To detect to interface card, I looped over all slots to check in its firmware for $B0 at location $Cx01 and $20 at location $Cx09 beeing x the slot number. I never found this 'signature' in any other firmware. To check for the pen position one has to poll the tablet (again beeing x the slot number): LDA $CFFF ; switch off all extension ROMS LDA $Cx00 ; switch on the extension ROM of the tablet LDA #$Cx STA $07F8 ; initialize some hidden text screen data area for the tablet firmware JSR $CBB9 ; call well known location ;-) in tablet firmware When the pen is in reach of the tablet (up or down) this routine will return immediatly. Else it will block - fortunatly the routine checks the keyboard strobe ($C010) too and will also return if a key is pressed, even if the pen remains out of tablets reach. After the routine has returned one can get the information: $0280 contains the state of the pen (up or down), I don't know excatly any more wich bit it is nor if one can distiguish between 'pen up' and 'pen out of reach but key pressed' $0281, $0282 contains the absolute X position of the pen $0283, $0284 contains the absolute Y position of the pen As far as I can remember the values have about 12 bit resolution (!). Usually I needed screen coordinates (280 x 192), so I dropped the 4 least significant bits and did some additional adjustment. Unfortunatly I can't remember either what coordinates will be there in the 'out of reach but key pressed' case. Hope this helps a little - if somebody has success using this method, please give me some feedback. BTW: I'm working on an Apple ][+ emulator, but suffer from a total lack of infos about the Apple ][ mouse (I think it goes into slot 4 and uses some interrupt stuff ???) due to the fact that I have never even seen such a mouse. Any way I'd like to build support for it into my emulator. So what ports - what firmware - ... thanks for help in advance. Oliver EOF