Yarrb - redesigned

emulators, hardware and classic software for atom + system machines
highfell
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Re: Yarrb - redesigned

Post by highfell » Tue May 05, 2020 10:00 am

hoglet wrote:
Tue May 05, 2020 9:25 am
highfell wrote:
Tue May 05, 2020 9:16 am
I am though going to do some tinkering (in the meantime), and thought I would remove his MMC EPROM from the #A0000 location and insert it into the Dos rom socket of my Disk Drive unit and see if I can get any success loading and saving programmes from there.
I'm sure you already know this, but I'll say it anyway.... You will need a different AtoMMC ROM that has been designed to run at #E000.

Dave
Thanks Dave. Appreciate your comments. I knew that it needed tweaking , but was interested to see as what the result is just using the Rom he sent me and whether it might work to an usable extent.

I guess you are gently informing me that I will be wasting my time :D

Cheers

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hoglet
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Re: Yarrb - redesigned

Post by hoglet » Tue May 05, 2020 11:33 am

highfell wrote:
Tue May 05, 2020 10:00 am
Thanks Dave. Appreciate your comments. I knew that it needed tweaking , but was interested to see as what the result is just using the Rom he sent me and whether it might work to an usable extent.

I guess you are gently informing me that I will be wasting my time :D
Yes, definitely wasting your time.

The #A000 version will just crash if you try to run it at #E000, because 6502 code isn't position independant.

This is where the story get a little more complicated...

The #E000 version of AtoMMC works a bit differently from the #A000 version. It's not possible to use an IRQ interrupt to automatically initialize a ROM at #E000, so instead the #E000 version of AtoMMC normally relies on a patched MOS ROM for initialization. This is very easy to do if you are using a modern RAMROM board, but a bit harder to so with an unmodified atom.

Without the patched MOS ROM you would been to manually initialize AtoMMC each time you press break, by typing LINK#E000.

If you are able to program 2532A EPROMs, the #E000 version of AtoMMC can be downloaded here:
https://github.com/hoglet67/AtoMMC2/releases/latest

Dave

devnuller
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Re: Yarrb - redesigned

Post by devnuller » Thu May 07, 2020 6:02 pm

Hi Roland,

If you do another batch of yarrb2 boards, I would gladly take one off your hands.

Regards,

Gert

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roland
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Re: Yarrb - redesigned

Post by roland » Thu May 07, 2020 7:35 pm

Since I have now three new orders, I have ordered a new batch of 5 pieces. I'll keep you informed about the progress.
FPGAtom: 512 KB RAM, Real Time Clock and 64 colours
MAN WOMAN :shock:

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roland
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Re: Yarrb - redesigned

Post by roland » Sat May 09, 2020 7:34 pm

The order is accepted and paid. I expect the boards to arrive in about four weeks.
FPGAtom: 512 KB RAM, Real Time Clock and 64 colours
MAN WOMAN :shock:

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roland
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Re: Yarrb - redesigned

Post by roland » Fri May 22, 2020 4:36 pm

I got an update today. It's ready and shipped and will arrive in about a week from now.
W126761YSY8-01.jpg
Final inspection board from PCBWay.
FPGAtom: 512 KB RAM, Real Time Clock and 64 colours
MAN WOMAN :shock:

devnuller
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Re: Yarrb - redesigned

Post by devnuller » Mon May 25, 2020 5:25 pm

Looks really nice. Anticipation level just rose a couple of points :D

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roland
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Re: Yarrb - redesigned

Post by roland » Mon May 25, 2020 10:09 pm

The new batch has not arrived yet and seems to be sold out already :shock:
FPGAtom: 512 KB RAM, Real Time Clock and 64 colours
MAN WOMAN :shock:

devnuller
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Re: Yarrb - redesigned

Post by devnuller » Wed Jun 03, 2020 8:39 pm

The yarrb2 has landed in my Atom:
yarrb2 installed.jpg
Very nice board Roland!

Regards,

Gert (devnuller)

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roland
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Re: Yarrb - redesigned

Post by roland » Thu Jun 04, 2020 7:50 am

Looks good, have fun with it!
FPGAtom: 512 KB RAM, Real Time Clock and 64 colours
MAN WOMAN :shock:

devnuller
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Re: Yarrb - redesigned

Post by devnuller » Fri Jun 05, 2020 4:27 pm

Hi Roland,

Have a question about the RAM bank switching on yarrb2. In your original posting (viewtopic.php?f=44&t=11373) on the first yarrb board, you mention a bank switching capability of the 16 kB memory block between #4000 - #7FFF (8x16 kB).

Judging on the VHDL code (https://github.com/AtomicRoland/yarrb2- ... ecoder.vhd) and the documentation you posted earlier in this topic, bits 0-2 in #BFFF (BS0,1,2) appear to control bank switching of the memory block between #A000 - #AFFF and bit 0 of #BFFE determines whether this is mapped to RAM or ROM.

Am I correct in assuming the the bank switching of the 16kB between #4000 - # 7FFF is not available in yarrb2 or is there a way of accessing the full 128kB RAM?

Related to this, are the Atom #A000 banks 0..7 on the yarrb2 pre-programmed and if so, what does each bank contain?

Regards,

Gert

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