exxos's Atari, Amiga & retro forum

Hi all, has anyone ever dropped a ST(M) keyboard into a MegaST keyboard housing? I have a UK ST KB that I want to drop into a US Mega case. It seems to fit and it looks like I just need to extend the internal cable?

Electrically the ST keyboard will work with a mega. You would need to terminate the ST keyboards electrical connections into the standard mega 6 pin connector and final a way to mount that connector in the proper spot.

Don't you have to have some sort of reset circuitry as the motherboard usually resets the keyboard on power-up?

Yep,the Mega doesn't have a reset line AFAIK and when I tried to hook up a regular ST keyboard to my Megas, it didn't work.

Still need to circle back to that project to see if there is a way around it.

stephen_usher wrote: ↑Fri Oct 23, 2020 2:40 pm Don't you have to have some sort of reset circuitry as the motherboard usually resets the keyboard on power-up?

Yes, the reset line on the ST keyboard processor is wired directly to the connector... no pullup resistor or anything. I can't remember what I ended up using.. just that it wasn't a big deal hence it didn't even rate a memory. If I'd had a case I'd still be using it.

rubber_jonnie wrote: ↑Fri Oct 23, 2020 4:44 pm Yep,the Mega doesn't have a reset line AFAIK and when I tried to hook up a regular ST keyboard to my Megas, it didn't work.

Still need to circle back to that project to see if there is a way around it.

Jon, I think you you should circle back on this one all though I have been very happy with the Eiffel interface. I'm not much of a game player so I've never used the joystick ports on the Eiffel with joysticks. I did test them with the Atari test suite and they both fail.

@PaulJ I'll definitely come back to it

Right now I'm using a spare MegaSTE keyboard and that works fine. Bear in mind it is an original ST (not an F/FM) keyboard I'm going to use. The internal connector looks identical bar colour and length.

The other (small) drama is I don't have a cable for it, so I will have to make one as well. All the shops are shut locally so I can't go in and browse for spares. PITA when you need to see how big a cap is. :-/

What I do have is what I believe is a Lighthouse KBD case, and it has a small PCB inside, be interesting to see what that does. Only trouble is that it's for an original 520ST KBD with the longer connector to account for the mouse and joystick ports off on the mainboard, so I need to get the pinouts and see if it does anything with reset or just converts to a different plug. My plan is to make a spare Mega KBD out of it if I can.

I should probably scope the reset pin, see what it does during power on, reset, normal use etc.

Ah, I see. I seem to recall all this when I towered my Falcon. I have an ST keyboard in a free keys case hooked to that. I have also used the MegaSTE KB with that, but, the mylar on all four of my MegaSTE/TT keyboards has gone to crap so I need to repair them. The reset line I have hooked to the PC tower case reset switch. I'd forgotten about that. Its handy having the turbo switch for the CT2 as well.

I'll see what I can rig tomorrow. Maybe a cable for the Falcon. I found your last discussion on KB's. I will have a crack at setting up my spare freekeys for the MegaST too. It might be of some help to you. From what I can see, the ST keyboard should be a drop in replacement.