SD Card Choice ?

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Crazyboss
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SD Card Choice ?

Post by Crazyboss » 13 Mar 2015 11:15

Hi.

Is the Rememozier compatible with all SD cards ?

I remember in the past I got SD cards, which look a like but didn work in older CAM's

I think it was the SD cards marked "HC" ?

I plan to test a microsd using an adaptor later ;)
//CLAUS - Webmaster at www.mtxworld.dk

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Dave
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Re: SD Card Choice ?

Post by Dave » 13 Mar 2015 12:02

Hi Claus,

Have you read the size restrictions on Andy's REMEMOrizer Hardware page?

Max supported size is 1GB, and with only 64MB used, there's no point in exceeding this anyway

I use microSD cards with adapters with no problems

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Dave

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Re: SD Card Choice ?

Post by Crazyboss » 13 Mar 2015 14:22

Actually currently I have 4 sd cards laying around the "Memotech MESS CORNER" :)

128mb/512mb/1gb + the 1gb which came with the Rememorizer.

I know only 64mb can be used no madder the size, I just recall some HC marked SD cards did not work in older digital cams. I dont know if its cause they run on lower voltages or something?

Just wondering of the Rememorizer will work with HC marked SD cards.

But if one 1gb are supported, does it mean a 2gb card will not work?

I have a 2gb around from a Samsung Phone, its a microsd, and I have a adaptor, so will try it;)

Its good to have something to switch around.

I use the CPMCBFS (windows 7), it might not be a great idea for a SD card, cause all data is written back to the sd card everytime i want to "upload a new version". But it works very good. I remember Andy told a SD card is not ment to read and write so much. It dont work like a harddisk or floppy disk, and you should not defrag a sd card. I dont know what will happend in the long run. But I think the issue is like a empty "sector" can not be overwritten with new data or maybe it can only be overwritten a number of times?
//CLAUS - Webmaster at www.mtxworld.dk

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Re: SD Card Choice ?

Post by Dave » 13 Mar 2015 15:20

Hi Claus,

I'm no expert (before anyone else highlights that!), so, FWIW, here are my comments......

There IS a maximum limit above which a card won't work, Andy advises that the limit is 1GB and I have no reason to doubt it, and in fact, do have reason to support it. When I made my REMEMOTECH, I missed the note about the 1GB max and initially tried a bigger card - it was probably either 2 or 4 GB, I can't recall which. It did not work, I'm pretty sure that the code will be the same as used in REMEMOrizer, so, just save yourself the hassle and stick to <= 1GB. But, as you have a card, you have nothing to lose but time, so just try it.

As I said, I use micro SD card adapters with no problems, old micro SD cards from old mobile phones are a good option.

Yes, SD cards, and flash memory in general, have a limit on the number of write cycles. Do a "Google" and/or look at some of the vendor sites, e.g., Kingston or Sandisk. Older technologies might have been as low as 10k, but these days, they are 100k to >1mm, so doing a few extra writes as you update the card is really not a problem. The vendors also tend to use "wear levelling" which helps. I don't think you will see any problems using the card the way that you describe, and hey, if you do, that's why we have backups, right?

For info, and of no statistical significance........
I have only ever had 1 SD card fail. It was in my Solar Power generation system, that writes a pretty small amount of data to the card every 5 minutes, for, on average,12 hours/day. The card gave up just a shade under 4 years of continuous use. Even then, I could read the data off it, just no longer write to it.

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Dave

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1024MAK
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Re: SD Card Choice ?

Post by 1024MAK » 13 Mar 2015 15:51

There are many variations of flash (or EEPROM / E2PROM ) memory. The different types have different speed and rewrite characteristics. As Dave says, early types had a relatively small number of write cycles before rewriting failed. More modern types are a lot better.

The bigger problem is that when the SD card in use does fail, it will be difficult to get replacements that are < 1 GB.

Already it is hard work to find smaller capacity SD cards :( And for devices that use CF cards, the situation is just as bad :twisted:

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Re: SD Card Choice ?

Post by Dave » 13 Mar 2015 16:40

Though not relevant to Claus's "problem" . . .

For CF, you may want to take the opportunity to pick up a few, brand new, 128MB cards that someone not a million miles away has just picked up and would consider offers on :-)

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Dave

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Re: SD Card Choice ?

Post by Crazyboss » 13 Mar 2015 18:00

if its to hard to find sd cards less then 1gb maybe Andy will fix it in the firmware, if possible?

and yes dave, the way i use i always have the imagefile on the pc, so always have a fresh backup :) we could wish for a drag draw windows driver, but the cpmcbfs is quite good, maps a drive e.g. s: and then you just put ur files here and write the img back to the sd card, and put it in your rememorizer ;)
//CLAUS - Webmaster at www.mtxworld.dk

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Re: SD Card Choice ?

Post by AndyKey » 19 Mar 2015 19:18

The size limitation comes from the sector size.
Larger cards have to have sectors > 512 bytes.
Memory space for buffering is a problem in the CP/M and SDX ROM drivers.

Yes, I'd recommmend buying a few <=1GB cards, while they're still available.
{{{ Andy

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