79 column mode?!

[nikoniko]

Just noticed when typing a long line of BASIC into x128, the 80th character column doesn't exist. Well, it does exist internally, but VICE doesn't bother to display it for some reason. Whatever character you type in that column is hidden, then the following one continues normally on the next line.

For so long I had my 128 without monitor and longed for 80 columns, then my 128 died before I could buy a monitor, then VICE started emulating the 128 but without any 80 column support, then VICE added 80 column support but it's really 79 columns... so all these years later, I still haven't realized my 80 column dream. :(

Actually, one pixel of the 80th column is shown. I guess 79 1/8th is better than just 79. :D

[Stephane Richard]

Yeah, I reported that bug about 2 months ago to the vice team...if you find VICE 1.16 or below, you'll notice the 80 column display shows all 80 columns.  So the VICE team knows about the bug already. :-).

Hopefully Verion 1.21 will reflect this correction. :-).

You'll notice as well that you can't overwrite an existing file in VICE (atleat not for d71 and d81 drives.  Maybe some real 128 user here can tell me if it's a bug or an actual feature.  Basically, I need to delete the file from the drive, then resave to get the updates.

VICE doesn't report an error, but if I close it and reload it, I can see the last changes are not present in the drive.  I've reported that bug to the vice team as well a while back, if it's not standard behavior, then it should be fixed in 1.21 as well.

[nikoniko]

Well, now they have two reports. It wasn't listed on their Bugs page, so I already went ahead and submitted it.

I wish they had better resources for following development, eg. access to CVS with the most recent work, some sort of mailing list so that people interested in development can exchange information and help one another, some way to know what bugs have been reported, and so on.

I've spent a little while studying the VDC code and taking some notes about how it works so that I can hopefully improve the emulation a bit. One thing is to fix the border color as I mentioned in another thread, another is to allow tall video modes to display in full instead of being cut off at the bottom of the window. Both of those I have some idea how to fix, but I haven't really looked into the text display issue yet. Eventually I'd also like to have a proper scaling option so that 80 column modes display in the right aspect ratio (very tricky, since there are so many weird resolutions possible), but that's a lower priority for me until other things are sorted out. There also seems to be space missing from the top and bottom border area; perhaps not terribly important, but it screws up vertical centering. Maybe that's something which can be addressed together with tackling the extended video modes.

[Stephane Richard]

Thwoudbe great if that could be accomplished yes. :-)

[nikoniko]

I've fixed the borders so that they change color when they're supposed to, but obviously it still needs a bit of work.

[nikoniko]

My previous solution to the 80 column problem was naive and broken. I've since realized that the issue is related to VDC register 25. The lower 4 bits control horizontal smooth scroll and I think should probably be zero on startup, but this appears not the case and so the screen ends up being shifted to the right. You can verify this in VICE by the following command:

SYS DEC("CDCC"),64,25

Now we can see our 80th column.