MEGA ST2 - "random" characters on the screen

[DominoTree]

And yeah, it’s a bad approach overall - if I hadn’t spotted corrosion on two of the PLCC sockets I wouldn’t have torn it down - at this point everything I want to really inspect and test is off the board and I’m adding sockets for everything

I also remembered that I get keyboard “beeps” when text is displayed in the screen and none of my other STs do that either - I feel like there is probably an enable line somewhere not being pulled up/down properly

[mfro]

I also remembered that I get keyboard “beeps” when text is displayed in the screen and none of my other STs do that either - I feel like there is probably an enable line somewhere not being pulled up/down properly

Keyboard beeps? The keyboard can't beep.

Anyway, that might indicate a pattern.

The VT52 terminal bell is supposed to be triggered by a BEL (007) character. So probably just another character (except ESC we have seen earlier) that doesn't behave as it's supposed to (might even be ESC is interpreted as BEL?). Find out if the character is wrong already when its sent to the terminal of if it's just interpreted incorrectly.

Can't see how that should be related to the keyboard.

[Steve]

Well there you go...

Any non-GEM app that outputs text does the same thing unless I do something like hold my finger over the keyboard connector, and then it just behaves normally. Everything else seems fine. Sometimes putting my finger there is required for the keyboard to even work in the first place.

So it seems you need to re-solder the keyboard connector motherboard side & perhaps replace the connector on the keyboard end. This bad connection sounds likely to be influencing the issue.

[DominoTree]

Well there you go...

Any non-GEM app that outputs text does the same thing unless I do something like hold my finger over the keyboard connector, and then it just behaves normally. Everything else seems fine. Sometimes putting my finger there is required for the keyboard to even work in the first place.

So it seems you need to re-solder the keyboard connector motherboard side & perhaps replace the connector on the keyboard end. This bad connection sounds likely to be influencing the issue.

Ha, was the first thing I tested/checked. Also rigged up an ST keyboard as well as an Eiffel clone I'm building with the same results.

[DominoTree]

I also remembered that I get keyboard “beeps” when text is displayed in the screen and none of my other STs do that either - I feel like there is probably an enable line somewhere not being pulled up/down properly

Keyboard beeps? The keyboard can't beep.

Anyway, that might indicate a pattern.

The VT52 terminal bell is supposed to be triggered by a BEL (007) character. So probably just another character (except ESC we have seen earlier) that doesn't behave as it's supposed to (might even be ESC is interpreted as BEL?). Find out if the character is wrong already when its sent to the terminal of if it's just interpreted incorrectly.

Can't see how that should be related to the keyboard.

Meant the "beep" that TOS normally makes when you press a character on the keyboard

[Steve]

If you boot up without the keyboard plugged in do you still get the weird characters on screen? Or have you not checked this yet. I think mfro is on to something with the terminal raw mode idea.. Not sure how you diagnose this though.

[DominoTree]

If you boot up without the keyboard plugged in do you still get the weird characters on screen? Or have you not checked this yet. I think mfro is on to something with the terminal raw mode idea.. Not sure how you diagnose this though.

Exact same behavior with no keyboard hooked up.

[mfro]

Meant the "beep" that TOS normally makes when you press a character on the keyboard

Sure it's the keyclick sound and not the terminal bell (the sound when you click outside a dialog box)?
You still did not say how the machine behaves if you boot without AUTO folder programs.

[DominoTree]

Hmm, it could actually be a BELL, I’m not sure now but I’ll make a note when I get everything back together

I mentioned it in a previous post but it got buried, everything works fine without any AUTO programs but if I do run something that outputs text and doesn’t use GEM it still does the same thing if there's no keyboard plugged in or sometimes if my finger isn't near the connector.

Otherwise everything seems fine except for the keyboard not working sometimes if I don’t have my finger near the connector while booting - just acts like it’s unplugged

[DominoTree]

Found a factory error (one of the inductors on the parallel port only had two out of three legs) and RP7 had a bad connection on one of the lines it’s supposed to pull up

Ran out of desoldering alloy (I always use it on old boards in conjunction with my Hakko 472D to keep temps at a minimum so pads don’t get lifted) - still want to get the YM2149 and the MFP socketed too but that’ll have to wait until Monday and I can still test their connections in place easily

So that brings us up to two additional bad connections I’ve found that could be related - RP7 and the MMU - still got more testing to do and sockets to install but I’ll feel a lot better about the board itself once this is all done, and having everything socketed is gonna be super helpful as I continue to prototype new hardware for this thing