Table of Contents

The Open Source Cartridge Reader (OSCR) supports SD cards of all sizes formatted as FAT, FAT32, or exFAT. Please note that the use of exFAT formatted disks may be slower than FAT32 formatted disks due to exFAT using 64-bit integers.

Selecting an SD Card

Due to the relative cheapness of SD cards these days, it's recommended you get a card specifically for the OSCR rather than sharing one with other devices. For the best experience, use an SD card that is 32GB or smaller. Larger cards may work, but they are unnecessary as ROMs and saves are quite small. If you want an idea of how many ROMs a single SD card can hold see the table below. It lists the typical maximum size of a ROM and minimum number of ROMs for some common systems. Keep in mind that most games were far below this value so these cards will likely hold more than stated.

System/Console	ROM Size*	32GB	16GB	8GB	Max**
N64	64MB	512	256	128	4.92GB
Game Boy	8MB	4,096	2,048	1,024	569MB
Game Boy Advance	32MB	1,024	512	256	6.81GB
NES	1MB	32,768	16,384	8,192	238MB
SNES	6MB	5,461	2,730	1,365	1.61GB
MD/Genesis	5MB	6,553	3,276	1,638	695MB
Master System	4MB	8,192	4,096	2,048	43.2MB
				Total	14.84GB

*The largest ROM size is either based on the largest ROM from an original cartridge or the maximum theoretical size supported by a system.

**Max is the total rough size of the known dumped games.

As you can see, 8 or 16GB is likely enough for most people. However, with how cheap SD cards are these days, 32GB can often be found for the same price as an 8GB or 16GB card. The only benefit of larger cards is that they can usually take more write cycles before wearing out.

The speed of the SD card does not generally affect how quickly the OSCR can dump games. The only minor impact the speed of the card has is how fast you can copy games off of the card. However, games are so small that this will generally take seconds unless you've dumped a full collection of hundreds of games. When choosing a specific SD card, the quality of the card itself is more important than the speed. Recommended brands (linked to an Amazon listing) are listed below (in no particular order).

Buying whichever of the above is cheapest and in stock will provide good results for most people. There are some cards that simply don't work with no indication as to why, in this case just try another SD card.

Some SD card readers have issues properly formatting SD cards. If you do not currently have a reader then I recommend you get the SABRENT SuperSpeed 2-Slot USB 3.0 reader. It is $8 at the time of writing this and it is quite a good reader.

Once you have your card and a reader and are ready to use it with the OSCR follow the steps under "Prepare the SD Card" to get it ready. The rest of this guide is primarily written for Windows.

Prepare the SD Card

Before using an SD card with the OSCR first you should always format it, whether it is new or used. After that, we will copy the necessary files to the card.

Formatting the SD Card

You can use the SD Memory Card Formatter to format the memory card. If that doesn't work, try following the steps below to format your SD card. Once the SD card is formatted, it's time to copy the files to it.

Important: Formatting an SD card erases all data on the card. Be sure to select the correct drive when formatting. If you are not tech savvy you should consider unplugging any other external devices from your computer before following the steps below.

Press Win + R.
Type cmd.
Press Ctrl + Shift + Enter.
Click "Yes" if prompted.
Type diskpart and press Enter.
Type list disk and press Enter.
Figure out which disk is the SD card. If you aren't sure then remove it and run the above command again, reinsert it, and run the command again. The disk that vanished and reappeared is the SD card. If in doubt, disconnect all other drives. C: should always be Disk 0.
Once you are sure you've found which disk is the SD card, type select disk N where N is the number of the disk (i.e. select disk 1) and press Enter.
Type detail disk and press Enter.
Ensure the information looks reasonable (likely it will mention being an SD USB reader, i.e. mine says "SABRENT SD USB Device").
Type clean and press Enter.
Type convert basic and press Enter. This command may fail if the disk is already a basic disk, ignore it.
Type convert mbr and press Enter.
Type list partition and press Enter, it should say there are no partitions on the disk.
Type create partition primary and press Enter.
Type list partition and press Enter.
Verify partition 1 exists, that its type is primary, and that it is the only partition.
Type select partition 1 and press Enter.
Type active and press Enter.
Type format fs=fat32 label="OSCR" quick and press Enter.
Type exit and press Enter.
Type exit and press Enter (again) to close the Command Prompt.

You should now have a clean disk:

Example output:

C:\Windows\system32>diskpart

Microsoft DiskPart version 10.0.19041.964

Copyright (C) Microsoft Corporation.
On computer: AQUILA

DISKPART> list disk

  Disk ###  Status         Size     Free     Dyn  Gpt
  --------  -------------  -------  -------  ---  ---
  Disk 0    Online         5723 GB  1024 KB        *
  Disk 1    Online           29 GB      0 B

DISKPART> select disk 1

Disk 1 is now the selected disk.

DISKPART> detail disk

SABRENT SD USB Device
Disk ID: DBD446A5
Type   : USB
Status : Online
Path   : 0
Target : 0
LUN ID : 0
Location Path : UNAVAILABLE
Current Read-only State : No
Read-only  : No
Boot Disk  : No
Pagefile Disk  : No
Hibernation File Disk  : No
Crashdump Disk  : No
Clustered Disk  : No

  Volume ###  Ltr  Label        Fs     Type        Size     Status     Info
  ----------  ---  -----------  -----  ----------  -------  ---------  --------
  Volume 3     F   OSCR         FAT32  Removable     29 GB  Healthy

DISKPART> clean

DiskPart succeeded in cleaning the disk.

DISKPART> convert basic

The selected disk is not a dynamic disk.
Select a dynamic disk to convert to basic.

DISKPART> convert mbr

DiskPart successfully converted the selected disk to MBR format.

DISKPART> list partition

There are no partitions on this disk to show.

DISKPART> create partition primary

DiskPart succeeded in creating the specified partition.

DISKPART> list partition

  Partition ###  Type              Size     Offset
  -------------  ----------------  -------  -------
* Partition 1    Primary             29 GB  1024 KB

DISKPART> select partition 1

Partition 1 is now the selected partition.

DISKPART> active

DiskPart marked the current partition as active.

DISKPART> format fs=fat32 label="OSCR" quick

  100 percent completed

DiskPart successfully formatted the volume.

DISKPART> exit

Leaving DiskPart...

C:\Windows\system32>

Copying the Files

Now that the card is formatted, download the "Portable" zip file from the latest release and extract it to a folder. To extract a zip file, right-click on it, click "Extract All...", and then follow the prompts. Make sure you have this window and the SD card window open at the same time. If you Shift + Click on Explorer in the taskbar it will open a new window for you.

Inside the "Portable" folder that you extracted from the zip, you will find another called "SD Card", navigate into that folder. Select all the files in that folder and drag them into the SD card.

Next, right-click on the already selected files and click on "Properties", then tick the "Hidden" checkbox and click "Apply"/"OK".

If the files vanish you can make them visible to you in Windows by clicking on the "View" menu and ticking the "Hidden items" checkbox.

In Windows 11 the "View" menu looks different, but the steps are nearly the same. After clicking View (the icon at the top with 4 horizontal bars) move the cursor down to "Show" and then tick "Hidden items".

When on Windows 10 or 11, you will likely want to tick the "File name extensions" box as well. This option is right above the "Hidden items" checkbox.

Final Steps

There are two main ways to eject an SD card. One way is to right-click the drive in Windows Explorer and then click "Eject".

Another way is to click the icon in the tray and click "Eject".

When using the SD card with your PC you should always eject it before removing it from your computer. Failing to do this may cause file system errors to appear. If this happens, you will need to follow this guide again, including formatting the card, to ensure the issues are resolved. Simply allowing Windows to scan the disk for errors does not always fix the problems, unfortunately.

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