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From: Crown (all posts)
Date: 1998-05-22
Subject: Re: EMU bugs

Hi,

Zsolt:
>Thank you for the bug-list! It is a very big help for me.
Sure, will be hunting for more :)

>I tested the 512x384 mode, but I didn't find any keyboard bug. But I will
>test it again.
It's in the emulators interface part only (when you are selecting which file to load, while using the debugger if you press the F8
to step to the next instruction it will skip a lot and not only one, etc.
This was only in 512x384, in the other modes 320x200 400x300 were no problems.

>The 360x240 is not in the standard vesa mode list. I set the 320x240 vesa
>mode then
>I wrtiting directly into the vga registers. So it works only with S3
>chipsets. Sorry...
I guess you should write this into the docs of the EMU.

Meanwhile I figured out why was the emu in slow mode in line $d0:
The plus4 y coordinate system doesn't equals with the screen line system.
Line 0 is at 4 lines before the plus4 25 line character windows first line. So the first displayed line on a frame is line 275 (
Actually only the right half is displayed as border the left half is black) Line 0-3 are displayed as border lines, but in terms of cycle usage they are either normal display lines (Graphic acesses are happening from the TED), or bad lines (depending on Y scroll condition)
Line $4 is the first displayed window line in 25 line mode,
while line $8 in 24 line mode. Line $CB is the last displayed window in
25 line mode, and $C7 in 24 line mode. Line $CC is the first border line after the window in 25 line mode, while line $C8 in 24 line mode.
The last displayed line in a frame is line $FA. (Line numbers are reflected in $ff1d)
Check my previous other posting, this is all there, black on white.

You should also run the test program Marko sent to the list, if it gives the same results as a real Plus4, than you are pretty close to have perfect emulation, in terms of cycle usage and distribution.

Tibor Biczo / Crown of GOTU