Re: Thanks for the Verilog help

From: Jim Brain <>
Date: Sat, 14 Dec 2013 14:49:30 -0600
Message-ID: <>
On 12/14/2013 2:26 PM, wrote:
> On 2013-12-14, at 21:14, Jim Brain <> wrote:
>>> Datasheet says it “accepts 5V”, but “has 3.3V or 2.5V output capability”. The board doesn’t seem to provide any level conversion. How does this work in your setup?
>> Since 3V3 will support TTL levels (0 < .8V, H>2.0V, or maybe it's 2.4V...) it seems to work fine.  EasyFlash3 uses the same IC, and no level shifters, and works fine (well, except for one revision of the 64 mobo that drives RESET via a 555 without a current limiting resistor, meaning drivng reset from the expansion port requires a switch or something that can overpower the 555, but that's not a 3V3 IC's issue).
> I see. I am not sure what the problem is and if it has anything to do with the 3V3 but EasyFlash3 doesn’t really work when plugged into SX-64. I asked skoe about it but he probably didn’t find time to investigate it yet.

Not sure a lot of investigation is needed there.  The ribbon cable on 
the expansion port of the SX64 ruins all the signals, and EasyFlash and 
a lot of the newer cart options (Chameleon, 1541U, etc.) won't work when 
doing things that require tight timing.  If you could turn the EF3 
KERNAL replacement function off, I bet the EF portion would work, and 
1541U no doubt works as long as the function you are requesting does not 
require tight timing.

It's the cable, pretty much.  I bet if you pulled the case, and ordered 
a shielded ribbon cable (or better, created a non ribbon cable option), 
the problem would disappear.
> Anyway nice to see that you successfully entered the CPLD zone. Good luck, Jim.
> P. S. Please keep at least in the back of your head the atapi stuff we talked about ;-)

Yes, I have it here :-)

Jim Brain

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Received on 2013-12-14 21:01:56

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