Cable info to connect a Mega ST keyboard to a standard ST

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rubber_jonnie
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Re: Cable info to connect a Mega ST keyboard to a standard ST

Post by rubber_jonnie »

Afraid not no, though I may well have another go at some point.

It won't be soon though, as if everything goes to plan, we will be moving house in the next 12 weeks, so a bit otherwise occupied right now.
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Re: Cable info to connect a Mega ST keyboard to a standard ST

Post by mikro »

Accidentally, I've bumped into this thread while searching for something else but in the end, perhaps it is the same cause (missing a delay and connection to /RESET).

There are at least two HID (USB mouse/joystick/joypad) adapters to the DSUB9 connector which seem to have trouble with the MegaSTE/TT keyboards. And in my case, also in my Falcon.

Basically, in the Falcon case, the adapter (powered by DSUB's +5V) would confuse the IKBD controller upon boot. The confusion demonstrates as key presses not doing anything or printing different character each time (!). Interestingly, this behaviour is fixed when I press reset. Which sounds awfully similar to the known problems with the NetUSBee and CT60 power lines (where a delay waiting for +5V to stabilise is put in the works).

However in the MegaSTE/TT case, this doesn't help at all. And this thread has shown me why (at least that's my guess) -- the keyboard doesn't have a RESET signal connected. So unless I miss something, it seems that the keyboard is in the same state regardless if how many soft and hard resets you do, therefore unable to reset one more time (when +5V is OK).

Which brings me to question whether you @rubber_jonnie (or anyone else) had any luck making this adapter / delay circuit work?

EDIT: It seems that a year before @Steve managed to get it working even without the /RESET connection: https://www.atari-forum.com/viewtopic.p ... 04#p387304.
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Re: Cable info to connect a Mega ST keyboard to a standard ST

Post by rubber_jonnie »

mikro wrote: Thu Jul 04, 2024 10:50 am
Which brings me to question whether you @rubber_jonnie (or anyone else) had any luck making this adapter / delay circuit work?
I didn't, no and ended up getting Eiffel adapters, and the idea slowly slid off my radar.
Collector of many retro things!
800XL and 65XE both with Ultimate1MB,VBXL/XE & PokeyMax, SIDE3, SDrive Max, 2x 1010 cassette, 2x 1050 one with Happy mod, 3x 2600 Jr, 7800 and Lynx II
Approx 20 STs, including a 520 STM, 520 STFMs, 3x Mega ST, MSTE & 2x 32 Mhz boosted STEs
Plus the rest, totalling around 50 machines including a QL, 3x BBC Model B, Electron, Spectrums, ZX81 etc...
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Re: Cable info to connect a Mega ST keyboard to a standard ST

Post by stephen_usher »

The reset signal is there to keep the IKBD processor in reset until the system is up and running. The Mega/MegaSTE/TT keyboards have a timer circuit of their own to hold them in reset until the power is stable so doesn't need the one from the system.

I'm not sure what you mean by delay, the IKDB protocol is merely a serial connection.
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Re: Cable info to connect a Mega ST keyboard to a standard ST

Post by mikro »

Maybe my wording wasn't correct, I was referring to the delay discussed in this thread.

Thanks for the information about the timer! Apparently, it's not enough for the USB adaptor. And the lack of RESET means that If the timer screw up, there's no point of return, unlike ST/Falcon.
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Re: Cable info to connect a Mega ST keyboard to a standard ST

Post by ijor »

mikro wrote: Thu Jul 04, 2024 10:50 am However in the MegaSTE/TT case, this doesn't help at all. And this thread has shown me why (at least that's my guess) -- the keyboard doesn't have a RESET signal connected. So unless I miss something, it seems that the keyboard is in the same state regardless if how many soft and hard resets you do, therefore unable to reset one more time (when +5V is OK).
Even without a hardware reset signal, resetting the computer should still reset IKBD because TOS sends a reset command to the IKBD. Of course, if the IKBD processor is locked for some strange reason, it might not be able to receive any command. I would need to double check, but IIRC IKBD might lockup if a mouse button is pressed during start up.
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Re: Cable info to connect a Mega ST keyboard to a standard ST

Post by stephen_usher »

mikro wrote: Thu Jul 04, 2024 2:31 pm Maybe my wording wasn't correct, I was referring to the delay discussed in this thread.

Thanks for the information about the timer! Apparently, it's not enough for the USB adaptor. And the lack of RESET means that If the timer screw up, there's no point of return, unlike ST/Falcon.
You can unplug and replug the keyboard in to reset the TT/MSTE/MST keyboards, that does a power cycle on them.
Intro retro computers since before they were retro...
ZX81->Spectrum->Memotech MTX->Sinclair QL->520STM->BBC Micro->TT030->PCs & Sun Workstations.
Added code to the MiNT kernel (still there the last time I checked) + put together MiNTOS.
Collection now with added Macs, Amigas, Suns and Acorns.
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Re: Cable info to connect a Mega ST keyboard to a standard ST

Post by mikro »

@stephen_usher that's exactly what I do to work around the problem. The annoying part is that it is the keyboard's voltage problem, not PSU's so I have to either boot with the adaptor detached (easier) or to disconnect the keyboard, then the adaptor, then reconnect the keyboard and then the adaptor (annoying).
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