Jump to content
  • 0
Elektron72

VERA Line IRQ

Question

Looking at the VERA Programmer's Reference, it appears that the line at which the raster interrupt occurs is specified by the contents of VERA register $9F28 and one additional bit in register $9F26. However, given that the Commander X16 can have a maximum of 640 lines, shouldn't there be another bit to allow triggering an IRQ on lines past 511?

Share this post


Link to post
Share on other sites

2 answers to this question

Recommended Posts

  • 0

VERA's native resolution is 640x480. That's 640 pixels horizontally by 480 pixels vertically. So, there are no 640 lines, only 480.

Of course, there's also the part where there's no image output, but according to http://www.tinyvga.com/vga-timing/640x480@60Hz, even then there's only 525 scanlines. Anyway, I believe we can ignore those extra 13 scanlines we are not able to set the IRQ for.

  • Thanks 1

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Answer this question...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


×
×
  • Create New...

Important Information

Please review our Terms of Use