Crazy Demonic ][+ with a mind of it's own

8 replies [Last post]
Offline
Joined: Mar 4 2014
Posts: 18

This problem has gotten progressively worse. It happens with and without the keyboard attached. I've tried reseating chips but nothing seems to have made a difference.

Basically it types a paragraph of random (but uniform) letters then seems to hit return all by itself.

All the time it's doing this, it's beeping an awful lot, like an Apple possessed!

I can interrupt the mayhem intermittently with keypresses, but it continues to repeat the letter e.g. QQQQQQQQQQQQQQWWWWWWWWWWWWWWWWWWWEEEEEEEEEERRRRRRRRRRRR... etc

Are there any ICs I should pay special attention to?

I've searched but couldn't find an example where someone has had this exact problem.

AttachmentSize
screenshot 12.23 MB
screenshot 21.97 MB

Comment viewing options

Select your preferred way to display the comments and click "Save settings" to activate your changes.
Offline
Joined: May 27 2013
Posts: 792
Re: Crazy Demonic ][+ with a mind of it's own

I don't know about the ii+ but if it were any other Apple ii then I would say that one of the contacts on the keys were making contact intermittently. The keyboard needs repair IMHO.

Offline
Joined: Mar 4 2014
Posts: 18
Re: Crazy Demonic ][+ with a mind of it's own

I thought that initially, but this happens even with the keyboard disconnected Sad

speedyG's picture
Offline
Joined: Nov 16 2011
Posts: 2376
Re: Crazy Demonic ][+ with a mind of it's own

Such behaviour is normally related to the strobe and the AKS ( Acknowledge Keystroke )
the related chips are located at the row B and at position B2 ( NE555 ) B3 ( 74LS00 ) and B4 ( 74LS00 )
on mainboard.
all 3 chips together would cost less than 2 Dollars in local electronic shop or electronic shop at ebay
... replace all 3 and the trouble should vanish...

sincerely speedyG

__________________

In early days I had a lot of money but no time - now I have no money but a lot of time....
the second part includes less friends but a lot more joy on life....

Offline
Joined: Mar 4 2014
Posts: 18
Re: Crazy Demonic ][+ with a mind of it's own

Thank you! I'll purchase those or see if I have some in another working machine and test it out Smile

Offline
Joined: Oct 9 2013
Posts: 365
Re: Crazy Demonic ][+ with a mind of it's own

By the way, the "hitting return by itself" is simply reaching the 256 character limit and starting with a new prompt. Besides that I had no clue till Speedy gave you the lowdown! Laughing out loud
Zan

Offline
Joined: May 27 2013
Posts: 792
Re: Crazy Demonic ][+ with a mind of it's own

Looks like Speedy has given instructions on how to banish a demon.

whscullin's picture
Offline
Joined: May 27 2013
Posts: 7
Re: Crazy Demonic ][+ with a mind of it's own

Related, the beeping is probably Applesoft telling you you are approaching the 255 character limit.

__________________

Will

Offline
Joined: Mar 4 2014
Posts: 18
Re: Crazy Demonic ][+ with a mind of it's own

Thanks for all the help and suggestions guys, I got hold of the correct ICs as recommended by SpeedyG and sure enough, the madness has ceased!