YARRB [SOLD OUT]

discussion of games, software, hardware & emulators relating to the Acorn Atom and Acorn System machines.
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roland
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Re: YARRB [SOLD OUT]

Post by roland » Thu Jun 13, 2019 9:47 pm

OK, that is settled then :D
256K + 6502 Inside
MAN WOMAN :shock:

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etaoin
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Re: YARRB

Post by etaoin » Tue Jul 02, 2019 6:39 pm

Ok, almost working...

It is randomly switching graphic modes if I leave it alone. I'm sure I've seen that mentioned somewhere but can't find it right now. Something for tomorrow.
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anightin
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Re: YARRB [SOLD OUT]

Post by anightin » Tue Jul 02, 2019 6:44 pm

Here are my settings:

JP3 on 1-2
JP4 on 1-2 (pin 1 is at the CPLD side).
JP5 and P5 closed
P4 and P6 open


I notice you have JP5 open?


Best

Andy
Last edited by anightin on Tue Jul 02, 2019 6:47 pm, edited 1 time in total.

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etaoin
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Re: YARRB [SOLD OUT]

Post by etaoin » Tue Jul 02, 2019 6:51 pm

anightin wrote:
Tue Jul 02, 2019 6:44 pm
I notice you have JP5 open?
No, JP5 is jumpered. P5 is open but that has been pulled up as suggested by Roland in his mods list.

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anightin
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Re: YARRB [SOLD OUT]

Post by anightin » Tue Jul 02, 2019 6:53 pm

Apologies, meant type P5 :oops:
To prevent writing to the EEPROM you can remove P5. But then you have to add a 4k7 resistor between the pins 31 and 32 of the EEPROM socket otherwise the EEPROM might not be readable (this is a design flaw in the board, this resistor should have been there).
Got it.
Last edited by anightin on Tue Jul 02, 2019 6:57 pm, edited 1 time in total.

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roland
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Re: YARRB

Post by roland » Tue Jul 02, 2019 11:29 pm

etaoin wrote:
Tue Jul 02, 2019 6:39 pm
Ok, almost working...

It is randomly switching graphic modes if I leave it alone. I'm sure I've seen that mentioned somewhere but can't find it right now. Something for tomorrow.
On the previous page, Sirmorris had solved this issue by replacing the 8255 and the chips in the clock circuit. If you have spares, this is worth a try. If you need a 8255 to test, just let me know.
256K + 6502 Inside
MAN WOMAN :shock:

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etaoin
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Re: YARRB [SOLD OUT]

Post by etaoin » Wed Jul 03, 2019 11:54 am

roland wrote:
Tue Jul 02, 2019 11:29 pm
On the previous page, Sirmorris had solved this issue by replacing the 8255 and the chips in the clock circuit. If you have spares, this is worth a try. If you need a 8255 to test, just let me know.
Yes, what he observed seems very similar. I'll first replace the sockets around the clock, as they're crap anyway. The 8255 already has a new socket and I think isn't the original 8255 anyway (it's a NEC chip). I've used lots of 8255's for DIY stuff ages ago so I probably pulled the original at some point and replaced it later. I probably have one or two (used) spares.

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etaoin
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Re: YARRB [SOLD OUT]

Post by etaoin » Thu Jul 04, 2019 7:15 am

Quick question: is the duty cycle of the 4 MHz clock expected to be way off 50%? Does the CPLD care anyway?
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etaoin
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Re: YARRB [SOLD OUT]

Post by etaoin » Thu Jul 04, 2019 7:21 am

etaoin wrote:
Thu Jul 04, 2019 7:15 am
Quick question: is the duty cycle of the 4 MHz clock expected to be way off 50%? Does the CPLD care anyway?
Sorry, I'm being stupid. My 12 MHz sample rate will skew the duty cycle.

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