RTC module for MegaSTe MonSTer

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spiny
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Re: RTC module for MegaSTe MonSTer

Postby spiny » Wed Sep 27, 2017 7:41 am

Fujiyama wrote:
But it would be nice to present a Y2K solution (with or without a battery backed add-on clock) for my musician friends who aren't going for a MonSTer board.



Bill Penners 'AReal' software is what you need:

areal37.zip


Y2K fixed, reads plenty of older clocks I believe, and more modern ones too. I'm pretty sure this is what I'm using to read the time from my Ultrasatan.
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Re: RTC module for MegaSTe MonSTer

Postby joska » Wed Sep 27, 2017 8:14 am

Fujiyama wrote:Because the expensive/hard-to-find lithium battery inside the Mega STe is dead, and with a MonSTer board installed I thought it might be a good idea to try out one of those cheap eBay RTC modules which uses easily available and cheap coin cell batteries.


Good point. However, there are other solutions than the weird battery. E.g the Stacy has the same RTC and use a regular 3V coin cell, and the Mega ST use two AA's. IIRC the Mega STE does not charge the battery either, so I'd say it's pretty safe to replace your battery with something like two regular AA cells. They won't last as long as the Lithium cell originally fitted to the MSTE, but I would expect them to work for atleast 5 years.

Edit: Turns out that troed wrote a blog post about this.

Fujiyama wrote:I believe I was told the clock didn't need any software at all and was completely transparent to the rest of the computer.


In that case it's the same RTC chip (or compatible) as originally fitted, and you don't have to do anything at all. Just check the battery.

Fujiyama wrote:With a patched TOS 2.06 flashed into the MonSTer I shouldn't have any issues with the add-on clock board in the STe.


If that clock is the same type as the original, factory-fitted clock there is no Y2K-problem to fix. No patch needed. If it's *not* the same as the original it's completely ignored by both TOS and the MonSTer RTC driver and you can pretend it's not there at all. That means that TOS 2.06 must be patched on that computer.

Fujiyama wrote:But it would be nice to present a Y2K solution (with or without a battery backed add-on clock) for my musician friends who aren't going for a MonSTer board.


Are they using TOS 2.06? If not, there is no Y2K problem to fix.
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Re: RTC module for MegaSTe MonSTer

Postby Fujiyama » Wed Sep 27, 2017 9:32 pm

joska wrote:
Fujiyama wrote:Because the expensive/hard-to-find lithium battery inside the Mega STe is dead, and with a MonSTer board installed I thought it might be a good idea to try out one of those cheap eBay RTC modules which uses easily available and cheap coin cell batteries.


Good point. However, there are other solutions than the weird battery. E.g the Stacy has the same RTC and use a regular 3V coin cell, and the Mega ST use two AA's. IIRC the Mega STE does not charge the battery either, so I'd say it's pretty safe to replace your battery with something like two regular AA cells. They won't last as long as the Lithium cell originally fitted to the MSTE, but I would expect them to work for atleast 5 years.

Edit: Turns out that troed wrote a blog post about this.


Yes, I've seen it before. Nice site.
I didn't know the clock could operate at 3V (instead of 3.6V), but then again I haven't read the datasheet for the clock chip. Interesting.
Yes, in that case I'd go for a 2x AA batteries as you suggested, in a battery holder mounted with velcro tape in the same place as before. There are actually AA lithium batteries with 1.5V power around, so two of those and it should last a lot longer.

But is there a downside to using the RTC module I attached to the MonSTer? Obviously I need to remember to put the driver in the AUTO folder (and again if configuring different boot-setups using a Boot-selector), but that's about it I guess?


Fujiyama wrote:I believe I was told the clock didn't need any software at all and was completely transparent to the rest of the computer.


In that case it's the same RTC chip (or compatible) as originally fitted, and you don't have to do anything at all. Just check the battery.


If that's the case -cool!
I don't know. I haven't really spent much time with it, but I can't remember ever having any trouble with it. Then again I was a much more active Atari user back in the late late 80's/throughout the 90s so I didn't encounter any Y2K problems of course.

I've just taken a look, removed the TOS EPROM and taken a couple of pictures as you can see here. I can see it contains a Ricoh RP5C15 clock chip, a 74HC688T, a 74HC00 on the rear side and a few other components (capacitor, resistor, diode etc.). I suppose there's a crystal in there somewhere as well (perhaps under the red wire).
Looking at the Mega STe schematic's clock section I see it uses the same RP5C15 clock chip, but a 4011, a couple of transistors and some other small parts (capacitors, resistors etc.). Obviously not a direct copy, and I don't know if the different ICs have an identical use or not. Apart from plugging into one of the TOS sockets there are two wires which go to the motherboard, one of them being to one of the serial chips (can't remember which one, but it's no obstructed by an ST_ESSC board which adds a couple of additional serial ports (just like the Mega STe). What do you think? An "original" clock or a third party clock as seen by TOS?

20170927-213041__MG_2174.jpg

20170927-152859__MG_2172.jpg

20170927-213041__MG_2174-2.jpg





Fujiyama wrote:With a patched TOS 2.06 flashed into the MonSTer I shouldn't have any issues with the add-on clock board in the STe.


If that clock is the same type as the original, factory-fitted clock there is no Y2K-problem to fix. No patch needed. If it's *not* the same as the original it's completely ignored by both TOS and the MonSTer RTC driver and you can pretend it's not there at all. That means that TOS 2.06 must be patched on that computer.


That's OK. I have both an EPROM programmer and will learn how to flash the MonSTer with TOS files.
Have you released that flashing program with the ability to add patches and a custom boot image?
I remember back in the day with SelTOS and all that, there were lots of TOS 2.06 fixes and improvements. Can any of those be incorporated into a TOS 2.06 to be flashed into the MonSTer?


Fujiyama wrote:But it would be nice to present a Y2K solution (with or without a battery backed add-on clock) for my musician friends who aren't going for a MonSTer board.


Are they using TOS 2.06? If not, there is no Y2K problem to fix.


Not sure. Different TOS versions I guess.
Funny that the Y2K problem was introduced with a newer (closer to the year 2000) TOS version while older ones wouldn't have that problem.
In the case of TOS 2.06 and an add-on clock I'll give the AREAL program Spiny attached above (Thanks Spiny!).
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Re: RTC module for MegaSTe MonSTer

Postby joska » Wed Sep 27, 2017 9:50 pm

Fujiyama wrote:There are actually AA lithium batteries with 1.5V power around, so two of those and it should last a lot longer.


Wouldn't it be easier to just go for the 3.6V cell troed used?

Fujiyama wrote:But is there a downside to using the RTC module I attached to the MonSTer? Obviously I need to remember to put the driver in the AUTO folder (and again if configuring different boot-setups using a Boot-selector), but that's about it I guess?


Correct. With the MonSTer RTC you need to run the driver from auto, with the stock RTC TOS takes care of everything.

Fujiyama wrote:I can see it contains a Ricoh RP5C15 clock chip


Same as stock Mega/Mega STE/Stacy RTC :) Sounds like all you need is a battery.

Fujiyama wrote:What do you think? An "original" clock or a third party clock as seen by TOS?


Almost certainly a clone of the stock RTC. Install a battery and try.

Fujiyama wrote:Have you released that flashing program with the ability to add patches and a custom boot image?


No. Too many other projects to spend time on :)

Fujiyama wrote:I remember back in the day with SelTOS and all that, there were lots of TOS 2.06 fixes and improvements. Can any of those be incorporated into a TOS 2.06 to be flashed into the MonSTer?


Yes of course. Look for "TOSPATCH", it's a huge archive with patches and a patching system. But read the instructions very, very carefully. It's quite complicated to use.

Fujiyama wrote:Funny that the Y2K problem was introduced with a newer (closer to the year 2000) TOS version while older ones wouldn't have that problem.


Well, we didn't start worry about Y2K until 1998 or so...
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