brett@umd5.umd.edu (Brett Bourbin) (06/15/89)
I am finishing the View display code for the current project I am working
on and wanted to make it work on PAL Amigas, along with the US models. What I
first decided to do was check the GfxBase->DisplayFlags and see if it's a PAL
screen, changing where the View positions itself. ( If it is a PAL display, it
starts the screen at line 28 and ends it at line 228 to center it. ) This is
done through the View->DyOffset.
What I was wondering about is what the proper procedure was for making
a screen on a PAL display that needs to be 320 by 200 lines. The main program
takes over the display when running, but can be paused to return it to any other
programs running in the background. I have my own drawing procedures and layout
that need a 200 line display. What do PAL screens look like when a 200 line
screen is opened up? Is it just a background color to the bottom of the extra
56 lines? What do other US/PAL programs do that do not open Windows on the
Workbench screen?
--
--Brett S Bourbin, Instructional Computing Programs -- Univ of Maryland
Computer Science Center, College Park, MD 20742
INTERNET: brett@umd5.umd.edu BIX: brettb DELPHI: brettbgregmarq@pnet02.cts.com (Greg Marquez) (06/15/89)
Brett,
I think I use the View->DyOffset trick to center the screens
of the PAL version(s) of a program I did. . .if so, the background color shows
up on the bottom lines.
Does your program re-direct requestors to your custom PAL
screen? If I remember right, there may be some problems with that (due to
screen-to-fronting or loadviewing?). . .when the requestor pops up, your
screen may "pop up" to DyOffSet = 0. . .test error conditions that cause a
requestor to pop up to see if it happens (an NTSC machine should be fine for
this test). Sorry about the vagueness, it's been a while.
Greg M
Richard G. Marquez / Echidna Software \|// Echidna - the best little
3501 Jasmine Ave. #15 / Los Angeles CA _oo // monotreme money can buy
90034
------- gregmarq@pnet02.CTS.COM ------ {decwrl, ames}!gryphon!pnet02!gregmarqvisinfo@ethz.UUCP (VISINFO Moderators) (06/22/89)
In article <5010@umd5.umd.edu> brett@umd5.umd.edu (Brett Bourbin) writes: > > I am finishing the View display code for the current project I am working >on and wanted to make it work on PAL Amigas, along with the US models. What I >first decided to do was check the GfxBase->DisplayFlags and see if it's a PAL >screen, changing where the View positions itself. ( If it is a PAL display, it >starts the screen at line 28 and ends it at line 228 to center it. ) This is >done through the View->DyOffset. My advise for that is: At any rate don't do the check this way, but simply look at the EXECBASE, offset 530 tells you the frequency of the vertical blank, which is directly connected to the PAL/NTSC status. If the VB frequency is 50Hz you obviously can display 256 noninterlaced lines. If it is 60Hz, you can only display a maximum of about 230 lines (overscan!). Some people take the height of the WB screen as a reference for PAL/NTSC. There is a number of reasons why you should not look at the height of the WB screen to decide if you have NTSC or PAL: * There is a Kickstart bug which sometimes enters 200 line mode on PAL Amigas * There are tools which can enlarge the WB screen (like VScreen) so that it is longer than the visible area and can be scrolled. In that case, you can have a 256 or more lines WB screen but still should not open your own screen other than 'normal' (200 lines) * There is now a tool (which I am developping myself) which can switch into a software emulated 60Hz mode on PAL (50Hz) Amigas at any time. In this case, you still have a long (256 lines) and PAL mode WB screen. Also, the View->DyOffset does not change. BUT all programs which open a screen should from that moment use an NTSC 200 lines configuration. A number of professional tools like CygnusEd, DPaint3, etc. already match these requirements. I am soon going to send further information about the 60Hz emulation, its purpose and how to handle it. > What I was wondering about is what the proper procedure was for making >a screen on a PAL display that needs to be 320 by 200 lines. The main program >takes over the display when running, but can be paused to return it to any other >programs running in the background. I have my own drawing procedures and layout >that need a 200 line display. What do PAL screens look like when a 200 line >screen is opened up? Is it just a background color to the bottom of the extra >56 lines? What do other US/PAL programs do that do not open Windows on the >Workbench screen? An NTSC (200lines) screen on a PAL configuration looks like this: It starts at the same location as a 256 lines screen but ends sooner. Below the bottom end of the screen you simply have its background color. To get this, you do not have to take any special measure. You simply open your screen with 200 lines - that's all! Imagine how incompatible it would be if there were anything you had to do! Friedemann Burgel UUCP: ...visinfo@bernina.UUCP BIX: hardwiz