Any unused IO on the STf mainboard?

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sety
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Any unused IO on the STf mainboard?

Post by sety » Sun Nov 18, 2018 6:40 am

Hi,

I have installed an internal IDE drive in my STF and changed the drive LED for a tri colour LED, so now I have red for FDD and blue for HDD. I have green left over. I was thinking that it would be really cool to have this (green) programmable and available to the user.

Does anyone know if there is an unused pin somewhere in the STF that I can tie this to?

Thanks,
Stuart

Petari
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Re: Any unused IO on the STf mainboard?

Post by Petari » Sun Nov 18, 2018 7:38 am

Good one :D
Atari is not known by putting unused pins and ports in his computers. Actually, Atari rather shared some ports between multiple peripherals. And that leads to possible solution: using PSG chip port B, which goes to parallel (printer) port connector.
You have there plenty of lines - of course, best if you don't use printer :lol: Some minor SW incompatibility is to expect.
There are some not used bits on port A too, but that is controlled by floppy access code, so will be problematic .
There is 2 kind of people: one thinking about moving to Mars after here becomes too bad, the others thinking about how to keep this planet habitable.

sety
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Re: Any unused IO on the STf mainboard?

Post by sety » Sun Nov 18, 2018 8:43 am

Petari wrote:
Sun Nov 18, 2018 7:38 am
Good one :D
Thanks. It actually looks really cool. I'm surprised it's not more of a common thing to do.
There are some not used bits on port A too, but that is controlled by floppy access code, so will be problematic .
This could be an option as I no longer use drive B, as I've swapped the pins on the PSG to allow A to be external and the HDD now resides in the internal floppy bay. I could hack TOS to stop it trying to communicate with drive B, but the problem is that I don't know enough about Assembly to do this myself. :( I don't even have a tool chain.

Perhaps if there is an expert out there who can tell me which bits to change in the binary to break communication with drive select for B it would be very much appreciated! :)

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Re: Any unused IO on the STf mainboard?

Post by Petari » Sun Nov 18, 2018 9:07 am

You can mod TOS, but lot of games will perform direct writing of constants to that port, and that will affect drive B selection line. What will not harm anything, so may be solution. But then is better to use unused bits 6 and 7. They are btw. used in Mega STE and Falcon.
I can do TOS mod, not right now, and need to know what TOS version you have. Actually, only 1.04 is what can be in question in case of ST. If have some older, this is good chance to upgrade.
Hmm. maybe TOS 1.04 already don't affect bits 6 and 7 of port B. You can check it if write there 0 or 1, and then measure with voltmeter (or attach LED, but not directly - must use some amplifier - PSG can not drive LED and 10-20 mA) is it changing during floppy access.
There is 2 kind of people: one thinking about moving to Mars after here becomes too bad, the others thinking about how to keep this planet habitable.

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Icky
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Re: Any unused IO on the STf mainboard?

Post by Icky » Sun Nov 18, 2018 11:10 am

Really cool idea. Where did you get the HDD activity line from. The HDD device itself or somewhere off of the STF board?

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Re: Any unused IO on the STf mainboard?

Post by Petari » Mon Nov 19, 2018 7:50 am

Icky wrote:
Sun Nov 18, 2018 11:10 am
Really cool idea. Where did you get the HDD activity line from. The HDD device itself or somewhere off of the STF board?
There is no HDD activity line in ST. Possible only from hard disk/Flash card adapter.
There is 2 kind of people: one thinking about moving to Mars after here becomes too bad, the others thinking about how to keep this planet habitable.

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Re: Any unused IO on the STf mainboard?

Post by Icky » Mon Nov 19, 2018 7:58 am

Petari wrote:
Mon Nov 19, 2018 7:50 am
Icky wrote:
Sun Nov 18, 2018 11:10 am
Really cool idea. Where did you get the HDD activity line from. The HDD device itself or somewhere off of the STF board?
There is no HDD activity line in ST. Possible only from hard disk/Flash card adapter.
Thanks Petari. I thought that is the case. I was just wondering if there was a way of getting the activity ie from the ACSI bus maybe. I am aware that would be ACSI bus activity and not true individual drives, but just a thought.

sety
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Re: Any unused IO on the STf mainboard?

Post by sety » Mon Nov 19, 2018 9:54 am

Icky wrote:
Sun Nov 18, 2018 11:10 am
Really cool idea. Where did you get the HDD activity line from. The HDD device itself or somewhere off of the STF board?
Sorry for the late reply. It was provided on Frank Luka's IDE board. The floppy LED came simply from drive select on the PSG but with a 220R resistor in line otherwise the floppy wouldn't work.

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