keiths@cadence.com (Keith Sabine) (05/22/91)
Hi, I wonder if anyone can help. I am trying to hook up a 68881 coprocessor to my 1040, to use with the Laser C floating point library (lib881). I have been following the datasheet instructions for the 68881 but am unsure whether I ve the addressing right. As I understand it, the Laser C library looks for the 68881 control register at address fffffa40 (found this by disassebling the code) so I have created address decode logic to drive CS true at this address. But what needs to be done with FC0-2? I am assuming that the 68881 is addressed in supervisor data space, but is this true? Anyone who may have done this, please email me or reply to the net, I'd appreciate some help. Keith.
apratt@atari.UUCP (Allan Pratt) (05/24/91)
keiths@cadence.com (Keith Sabine) writes: >I am trying to hook up a >68881 coprocessor to my 1040 ... >But what needs to be done with FC0-2? I am assuming that the 68881 is >addressed in supervisor data space, but is this true? Data space, but it need not be supervisor. We did this so programs and libraries could use it without becoming supervisor. ============================================ Opinions expressed above do not necessarily -- Allan Pratt, Atari Corp. reflect those of Atari Corp. or anyone else. ...ames!atari!apratt