Flash carts for the pc engine/turbo

[Arkhan]

The Neo Team flash devices also do not work on all NEC systems.

What makes you think that this Everdrive won't have similar problems with undervoltage in the HuCard slot?  I wouldn't be surprised if it isn't even less compatible, as it'll have to power the SD slot and bus in addition to a whole lot more flash memory.

I ALREADYSAID THAT.

in my tl;dr wall of text.

jeeeeze.

lol

[Mishran]

Well, folks, I am still interested in the original plan (neoflash group rate), even if this fellow in the Ukraine (shout out to a fellow Ukranian!) delivers a well-functioning device 7-12 months from now.

Perhaps a new thread for it is in order? Either way, I'm still interested as well.

[Necromancer]

I ALREADY SAID THAT.

Heh, yeah.... too many words to read. 

[lastcallhall]

So, I know I'm new here, but I've been an active member over at Sega-16 for a while now, and I would like to weigh in:

As an owner of an original Sega Everdrive, Super Everdrive, Master Everdrive and Everdrive 64, I can say with absolute certainty that Krikzz's products not only offer the most bang for the buck, but are made of high quality components, as well. Not a single drive has shown an error in the roughly year or so time span that I've owned the various devices. Like many, I have been waiting for a TG-16/PCE solution that was flash cart based to arrive, and it's nice to know that Krikzz has decided to work on one for us. Like Joe has said, however, he is a Sega man at heart and has opted to deliver an upgraded version of his original Everdrive (which sounds awesome by reading the specs) before he tackles any more projects. That said, I'm confident that he will deliver on all fronts by the time frame he's promised, based on his previous track record. To top it off, he's also gone on record saying the Everdrive-16, or whatever he decides to call it will land somewhere in the 70-80 USD range, which falls in line with his other products. I've looked at the Neoflash cart and it just doesn't compare. I'd gladly wait a few more months and play with the few Hu-Cards that I can, while I wait for this delicious piece of hardware to become available.

To me, it's a no-brainer.

[Arkhan]

It isn't the quality of the hardware that is the concern.

it's the obvious power-draw from anything more than a simple card game.

[lastcallhall]

If the PSU is generating ~750 mA, the power shouldn't be a problem. The Genesis can run off of ~350-500 mA without a problem, I refuse to believe that a PCE needs the majority of the 750mA to run the system without having enough to send a 5v signal to the card reader. Again, I'm somewhat new to the PCE technology - How much amperage is supplied by the cart slot?

[Arkhan]

If the PSU is generating ~750 mA, the power shouldn't be a problem. The Genesis can run off of ~350-500 mA without a problem, I refuse to believe that a PCE needs the majority of the 750mA to run the system without having enough to send a 5v signal to the card reader. Again, I'm somewhat new to the PCE technology - How much amperage is supplied by the cart slot?

It's an intermittent problem.  Not all units have it.  Sometimes the 5v line isn't powerful enough to power all kinds of dumbass addons. It's not part of the original spec: Game cards.

so, they obviously did not catch or care about it, I guess.

[lastcallhall]

Huh. Now I'm really curious to see what the problem is. Thanks for filling me in.

[TheOldMan]

Again, I'm somewhat new to the PCE technology - How much amperage is supplied by the cart slot?

Not sure, but at a minimum it would have to be enough to power an older EPROM chip.
If I read things correctly, that would be about 30 mA.
(from here: http://eshop.engineering.uiowa.edu/NI/pdfs/01/03/DS010329.pdf)

So, assuming you have (generously) 50 mA for the chip, that would allow you to -maybe- run 2 eeproms.
And, if they use a more modern (ie, lower current) flash chip, they -might- get away with running 4-5 devices at that load.

Personally, I believe the problem has to do with the 5V signals being under voltage due to the chips pulling (for just a bit) too much current. But I'm not sure about that, as my card works fine....
Would love to see some measurements of how much current -is- available on the 5V line, though

[thesteve]

i dont believe its a current problem.
the PCE/TG system has poor (non existent) data bus termination causing some cards not to function in some systems.
the data bus system (slot and expansion bus) is basically a SCSI concept and will run better with a terminator resistor on the ends.

[Supremo_Lagarto]

Again, I'm somewhat new to the PCE technology - How much amperage is supplied by the cart slot?

Not sure, but at a minimum it would have to be enough to power an older EPROM chip.
If I read things correctly, that would be about 30 mA.
(from here: http://eshop.engineering.uiowa.edu/NI/pdfs/01/03/DS010329.pdf)

So, assuming you have (generously) 50 mA for the chip, that would allow you to -maybe- run 2 eeproms.
And, if they use a more modern (ie, lower current) flash chip, they -might- get away with running 4-5 devices at that load.

Personally, I believe the problem has to do with the 5V signals being under voltage due to the chips pulling (for just a bit) too much current. But I'm not sure about that, as my card works fine....
Would love to see some measurements of how much current -is- available on the 5V line, though

Do you think it is possible that it might be that there is rippling or noise on that +5 volt line on some systems?

On my Duo I can play most games on the card for a full minute before they corrupt and freeze.

And if it is rippling, might there be a way to remedy that?

[thesteve]

yes line noise and bus noise are the likely catalyst.
capacitors are used to reduce it.

[Supremo_Lagarto]

How many volts and micro-farads should the cap be and where would it be placed?

[thesteve]

the cap would need to be 5V or more 6.3V and 16V are most common.
as to the uf it depends on how much damping you want.

where to hook it..........thats the big question.
the cap or caps should go where the problem noise is (id start with the 5V line)
CE is another, and would need to be a much smaller cap

i suspect a pull-up resistor array on the data lines may solve it good

[lastcallhall]

the cap would need to be 5V or more 6.3V and 16V are most common.
as to the uf it depends on how much damping you want.

where to hook it..........thats the big question.
the cap or caps should go where the problem noise is (id start with the 5V line)
CE is another, and would need to be a much smaller cap

i suspect a pull-up resistor array on the data lines may solve it good

Since all the noise would be carried throughout the circuit, couldn't you just toss a 220uF cap on right before hitting the 5v pin? that should clean it up, right? I don't have the board near me so I can't see how the PCB is laid out, but I would think that would be the simplest fix.