YARRB [SOLD OUT]

emulators, hardware and classic software for atom + system machines
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1024MAK
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Re: YARRB [SOLD OUT]

Post by 1024MAK » Fri Nov 15, 2019 12:40 pm

As the Western Design Centre W65C02S is designed for a much faster clock speed, it’s outputs will have much faster edges. Maybe this is causing problems.

Mark

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roland
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Re: YARRB [SOLD OUT]

Post by roland » Fri Nov 15, 2019 3:21 pm

There are no extra expansions, even the AtoMMC is not connected. It's just the new noise killer board and Yarrb but I cannot imagine that the noise killer also kills the Atom because the cpu can write to the video ram (clear screen and write ACORN ATOM >[] ) and it does not read the screen memory.

If wife and time permit I will do some tests this evening....
FPGAtom: 512 KB RAM, Real Time Clock and 64 colours
MAN WOMAN :shock:

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roland
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Re: YARRB [SOLD OUT]

Post by roland » Fri Nov 15, 2019 9:13 pm

I still couldn't find out the exact reason why my Atom was hanging but changing the 8255 solved the problem. I tried six of them and only one works. A 82C55 was even not able to put the 6847 in text mode :o

My AtoMMC also does not work. When I reset the Atom with CTRL+BREAK the test program for reading the heart beat works fine, it returns alternating #AA and #55. Also the verion (2C) and config byte are read. *CFG or *PBD give a DISK error. I did some measurements on the MMC board with my scope and the power lines had very much noise. I added a 100nF between VCC and GND of the 74LS75 and 74LS139. That cleaned the power lines but did not solve the problem yet. I can see clear pulses on the latch. The datalines look very curved but they also do with a normal 6502 and that still works.

So I have to get a good night sleep about this and how to troubleshoot this.....
FPGAtom: 512 KB RAM, Real Time Clock and 64 colours
MAN WOMAN :shock:

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roland
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Re: YARRB [SOLD OUT]

Post by roland » Sun Nov 17, 2019 1:10 pm

Due to the subject of this topic (Yarrb) and the new issue (W65C02 and AtoMMC) I moved the new issue to this new topic.
FPGAtom: 512 KB RAM, Real Time Clock and 64 colours
MAN WOMAN :shock:

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roland
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Re: YARRB [SOLD OUT]

Post by roland » Sun Nov 17, 2019 3:47 pm

Playing with the W65C02 ... it turns out that this is a very special CPU with very specific timing. On my Yarrb'd Atom with noise killer it works fine at 1 MHz, but at 2 MHz I notice a lot of screen corruption. So my advise for now is: forget the W65C02 unless you only want a 1 MHz Atom. Also in my Atom2k15 it does not work well, allthough it directly recognizes the onboard AtoMMC. For the rest: only troubles :(
FPGAtom: 512 KB RAM, Real Time Clock and 64 colours
MAN WOMAN :shock:

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marcusjambler
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Re: YARRB [SOLD OUT]

Post by marcusjambler » Mon Dec 30, 2019 9:18 pm

Hi Roland

The YARRB is now working great in this Issue 4 ATOM.
IMG_1143a.jpg
IMG_1145a.jpg
IMG_1147a.jpg
IMG_1161a.jpg
There are some artifacts appearing on the screen ( I'll make a post in the correct thread for the noise killer )

Also I have made good progress with adding a matchbox copro
But it is hanging when I run clocksp ( I'll make a post in the other correct thread )

Anyway... Really nice board....

Marcus

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