mig7920@cec1.wustl.edu (Mark Israel Gross) (03/09/91)
To anyone who can help: I am trying to develop an application which utilizes the alternate video buffer. According to IM this may not be supported in future versions but I suspect that it is available with my SE/30. From IM 3 I need to clear the 6th bit on the VIA buffer A which I do with: bclr #vPage2,vBase+vBufA IM 3 says that the segment loader must be made aware that you intend to use the alternate video buffer so that the memory is properly allocated. I achieve this by lea.l CurApName,A0 I then place a negative word into 4(A0) which is supposed to allocate the alternate video and sound buffers. N.B. the setup for the segment loader is done prior to clearing the 6th bit of the VIA buffer. I have noticed when using MacsBug that placing the negative number offset by (A0) destroys the string which contains the current application name. At any rate the series of calls inevitably crashes when I trap to the _Chain as instructed in IM. The application works fine when I use the Main Video Buffer so my setup in this respect is correct. Anyone having any Assembly language code dealing with this problem many Thanx in advance. Please E-mail to mig7920@cec1.wustl.edu If there is adequate interest I'll post to the net. Thanx for the BW Mark Gross