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50g freezes on SD card access
01-10-2020, 09:02 AM
Post: #21
RE: 50g freezes on SD card access
(01-10-2020 08:33 AM)JDW Wrote:  
(01-10-2020 08:18 AM)ijabbott Wrote:  Was the MicroSD card formatted as FAT32 or FAT16?

edryer needs to answer that question, but like I said before, my friend told me he formatted his SD card inside his 50g and he said it formatted it with FAT32. That contradicts what someone earlier in this thread said about FAT16 being the best. I would think the 50g would format cards in whatever format it considers "best." Which would indicate it thinks FAT32 is best. I've not tested formatting an SD card in my own 50g in a long while so I cannot say anything one way or another right now.

The calculator will format SD cards of <= 32 MB capacity using FAT16, for higher capacity cards it will use FAT32.
For 1 or 2 GB cards there is the problem that the calculator takes several seconds to access or access the card itself. This is because the calculator has to map a huge number of clusters. But it only happens the first time you access the SD card and in any case this does not slow down the calculation operations. Up to 512 MB capacity cards, access is almost immediate.
To overcome this drawback it is possible to format 1 or 2 GB cards using FAT16 which allocates less clusters, through the PC and a memory card reader using the DOS FORMAT command:

C:\> FORMAT F: /FS:FAT /Q

assuming that F: is the mounted memory card.

Of course it can also be done with GNU/Linux:

# mkdosfs -F 16 /dev/sda1

assuming that /dev/sda1 is the path of the mounted SD card.

But remember that to reuse the same card on other devices, such as digital cameras, it is good to reformat with FAT32:

C:\> FORMAT F: /FS:FAT32 /Q on DOS

# mkdosfs -F 32 /dev/sda1 on GNU/Linux


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Simone
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01-10-2020, 04:01 PM
Post: #22
RE: 50g freezes on SD card access
Use a PC to format the card, not the calculator.

You can use either FAT32 or FAT16, but I recommend FAT16. Picking FAT16 will give larger cluster sizes, which means you can fit fewer files on the card (though the reduction in limit is not meaningful for any typical use), because each file will take more size, but it also reduces the number of clusters on the card, which avoids the slow-power-on issues with large cards.

As I recall, FAT32 will use 8 times as many clusters as FAT16 with the default Windows cluster size, so the power-on delay is 8 times longer (which is effectively a couple seconds for a 2 GB card with FAT32 vs imperceptible with FAT16, if I remember right). I do not remember how the calculator handles non-standard cluster sizes.

The free space won't be reported correctly in Filer if you have over a gigabyte of free space, which means only cards up to 1 GB are 100% perfectly supported. However, 2 GB cards otherwise work just fine. It's getting harder to find cards under 2 GB nowadays anyway. Don't try anything bigger; I heard rumors of some SD (not SDHC) cards existing in the 4 GB size, but I haven't seen any myself, so anything over 2 GB is almost certainly not going to be compatible with the 50g OS.

I believe the SD vs SDHC limit is in software, not hardware, however, so I think it is theoretically possible that something with its own SD card implementation like newRPL could support larger capacity SDHC (or maybe even SDXC) cards but I don't know whether that is realistic.
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01-10-2020, 04:47 PM (This post was last modified: 01-10-2020 04:48 PM by edryer.)
Post: #23
RE: 50g freezes on SD card access
(01-10-2020 08:33 AM)JDW Wrote:  
(01-10-2020 08:18 AM)ijabbott Wrote:  Was the MicroSD card formatted as FAT32 or FAT16?

edryer needs to answer that question, but like I said before, my friend told me he formatted his SD card inside his 50g and he said it formatted it with FAT32. That contradicts what someone earlier in this thread said about FAT16 being the best. I would think the 50g would format cards in whatever format it considers "best." Which would indicate it thinks FAT32 is best. I've not tested formatting an SD card in my own 50g in a long while so I cannot say anything one way or another right now.

think the 2gb full size was fat16
not sure of the 2gb in the adapter though

I had heard the circuitry in the adapter was the issue, I didn't think they had any and were dumb pass-thru.

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01-10-2020, 06:06 PM
Post: #24
RE: 50g freezes on SD card access
(01-10-2020 04:01 PM)Eric Rechlin Wrote:  Use a PC to format the card, not the calculator.


You can use either FAT32 or FAT16, but I recommend FAT16. Picking FAT16 will give larger cluster sizes, which means you can fit fewer files on the card (though the reduction in limit is not meaningful for any typical use), because each file will take more size, but it also reduces the number of clusters on the card, which avoids the slow-power-on issues with large cards.

As I recall, FAT32 will use 8 times as many clusters as FAT16 with the default Windows cluster size, so the power-on delay is 8 times longer (which is effectively a couple seconds for a 2 GB card with FAT32 vs imperceptible with FAT16, if I remember right). I do not remember how the calculator handles non-standard cluster sizes.
Just wanted to add the bootloader can only read FAT16. This only means FAT16 is needed to update firmware via SD card. Everything else will work fine on FAT32.

(01-10-2020 04:01 PM)Eric Rechlin Wrote:  I believe the SD vs SDHC limit is in software, not hardware, however, so I think it is theoretically possible that something with its own SD card implementation like newRPL could support larger capacity SDHC (or maybe even SDXC) cards but I don't know whether that is realistic.

You are correct. The only difference between SD and SDHC is in software and newRPL supports SDHC cards, larger capacity is fine (although it raises the question: what for?), multiple partitions are fine, etc.
SDXC has a new high speed protocol for faster data transmission and 1.8V support, that's not supported by the hardware in the calculator (all decent cards, however, should offer a fallback mechanism to the old spec). Also, they have a different way to count sectors, since the number of sectors exceeds the 32 GB limit on SDHC. This is all in the SD 3.0 specification, but that could in theory be managed by software if the need arise. At this point, newRPL does not support SDXC cards, only SDHC (SD 2.0 specification).
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01-10-2020, 09:24 PM
Post: #25
RE: 50g freezes on SD card access
(01-10-2020 09:02 AM)Simone Cerica Wrote:  Of course it can also be done with GNU/Linux:

# mkdosfs -F 16 /dev/sda1

assuming that /dev/sda1 is the path of the mounted SD card.

/dev/sda1 is more likely to be the first partition of a system hard drive, so probably not the best example to use!

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01-10-2020, 09:40 PM
Post: #26
RE: 50g freezes on SD card access
(01-10-2020 04:47 PM)edryer Wrote:  I had heard the circuitry in the adapter was the issue, I didn't think they had any and were dumb pass-thru.

Yes, the adaptor is just a pass-thru with no active circuitry. A bog-standard SD card (not SDXC or SDUC) has 9 contacts whereas a MicroSD has only 8 contacts, but the missing contact is just another ground connection.

Mechanically, using the MicroSD adaptor is probably slightly less reliable than using A full size SD card, but apart from that, there shouldn't be any difference in performance between similarly specced SD and MicroSD cards.

— Ian Abbott
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