Jump to content
ubersaurus

Apple II+ graphical glitching

Recommended Posts

I'm trying to prep my Apple II for Magfest, and noticed some unusual graphical problems when trying to boot games. This occurs off the cffa and the actual Disk II drive. The bottom quarter of the screen in gameplay is full of garbage characters, while the loading screens have random characters basically the whole way through. Anyone know what the problem could be? Or how I can best find out?

 

I also got another error trying to load Dino eggs off the cffa. Not sure what that's about - I don't recall seeing it before. Still boots off the cracked disk, though? The cffa self test found no issues.

post-372-0-11603900-1546115356_thumb.jpg

post-372-0-06933200-1546115375_thumb.jpg

post-372-0-93241600-1546115430_thumb.jpg

Share this post


Link to post
Share on other sites

I believe there's a soft switch that turns the 4-line text area in hgr mode on and off. I think it's handled by the IOU chip, but I wouldn't swear to it. Could maybe be the MMU instead(?). My guess would be that something's not right with that, and it's not telling the video stuff to go full HGR mode so it's still pulling some junk out of the text page (which is probably being used for something else).

 

Unfortunately, I'm too ignorant to suggest anything to fix it, other than to try reseating the IOU, MMU, and video chips.

  • Like 1

Share this post


Link to post
Share on other sites

I'll second the softswitch mode of failure. But, the II+ doesn't have MMU or IOU chips. It's all discrete.

 

Perhaps look around F14, F13, or things to do with the nearby LS257 or LS259 chips.

Edited by Keatah

Share this post


Link to post
Share on other sites

I did a diagnostic program and it said the rom and ram chips are all good, so softswitch does seem likely - someone elsewhere pointed out it looks like an issue with the text/graphic modes intermingling. Could it be B12? I can check the F14 and 13 chips too.

 

Edit: forgot I already tried reseating f13 and f14 (and several other nearby LS chips) with no success.

Edited by ubersaurus

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
Reply to this topic...

×   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.

Loading...

  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...