{"id":1279,"date":"2026-10-23T06:40:34","date_gmt":"2026-10-23T06:40:34","guid":{"rendered":"https:\/\/www.r3tr0.net\/?page_id=1279"},"modified":"2026-10-23T06:40:35","modified_gmt":"2026-10-23T06:40:35","slug":"wmdoc_sd-card","status":"publish","type":"page","link":"https:\/\/www.r3tr0.net\/index.php\/wondermca-documentation\/wmdoc_sd-card\/","title":{"rendered":"WonderMCA: The microSD card"},"content":{"rendered":"\n<div class=\"wp-block-group wmdoc-hero has-text-color has-background has-link-color wp-elements-1 is-layout-constrained wp-container-core-group-is-layout-89221c49 wp-block-group-is-layout-constrained\" style=\"border-radius:10px;color:#edf5ff;background-color:#001141;margin-bottom:32px;padding-top:28px;padding-right:32px;padding-bottom:28px;padding-left:32px\">\n<p class=\"has-text-color wp-block-paragraph\" style=\"color:#78a9ff;margin-bottom:8px;font-size:13px;font-weight:600;letter-spacing:2px;text-transform:uppercase\">WonderMCA \u00b7 User documentation<\/p>\n\n\n\n<p class=\"wp-block-paragraph\" style=\"margin-top:0;font-size:19px;line-height:1.55\">What the microSD card must be, the folders and files the card looks for, the rules for image names, how the lists of the setup menu and of the screenpad show the card and a USB stick, the files the card writes itself, and the messages when the card cannot be read.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\" style=\"margin-top:12px;font-size:14px\"><a href=\"https:\/\/www.r3tr0.net\/index.php\/wondermca-documentation\/\">\u2190 WonderMCA documentation home<\/a> \u00b7 Page 3 of 18<\/p>\n<\/div>\n\n\n\n<div class=\"wp-block-group wmdoc-toc has-border-color has-background is-layout-constrained wp-container-core-group-is-layout-67fe145d wp-block-group-is-layout-constrained\" style=\"border-color:#dcdcde;border-width:1px;border-radius:8px;background-color:#f6f7f7;margin-bottom:32px;padding-top:16px;padding-right:24px;padding-bottom:16px;padding-left:24px\">\n<details class=\"wp-block-details is-layout-flow wp-block-details-is-layout-flow\" open><summary>On this page \u2014 6 sections<\/summary>\n<ul class=\"wp-block-list\">\n<li><a href=\"#what-the-card-must-be\">What the card must be<\/a><\/li>\n\n\n\n<li><a href=\"#folders-and-files\">Folders and files<\/a><\/li>\n\n\n\n<li><a href=\"#rules-for-image-names\">Rules for image names<\/a><\/li>\n\n\n\n<li><a href=\"#the-usb-stick\">The USB stick<\/a><\/li>\n\n\n\n<li><a href=\"#files-the-card-writes\">Files the card writes<\/a><\/li>\n\n\n\n<li><a href=\"#when-the-card-cannot-be-read\">When the card cannot be read<\/a><\/li>\n<\/ul>\n<\/details>\n<\/div>\n\n\n\n<p class=\"wp-block-paragraph\">The microSD card holds your disk images, your settings and the CPLD update files. This page tells you how to lay it out. The card and its socket are on <a href=\"https:\/\/www.r3tr0.net\/index.php\/wondermca-documentation\/wmdoc_hardware-installation\/\">02-hardware-and-installation<\/a>. The image formats are on <a href=\"https:\/\/www.r3tr0.net\/index.php\/wondermca-documentation\/wmdoc_disks\/\">08-hard-disks-and-floppy-disks<\/a>. Every key of <code class=\"\" data-line=\"\">config.txt<\/code> is on <a href=\"https:\/\/www.r3tr0.net\/index.php\/wondermca-documentation\/wmdoc_settings\/\">07-configuration-reference<\/a>.<\/p>\n\n\n\n<div class=\"wp-block-group wmdoc-callout wmdoc-warn has-background is-layout-constrained wp-container-core-group-is-layout-1828d0e2 wp-block-group-is-layout-constrained\" style=\"border-radius:6px;border-left-color:#d63638;border-left-style:solid;border-left-width:4px;background-color:#fdecec;margin-top:24px;margin-bottom:24px;padding-top:12px;padding-right:20px;padding-bottom:12px;padding-left:20px\">\n<p class=\"wp-block-paragraph\"><strong>Warning.<\/strong> Insert or remove the microSD card only with the PS\/2 off. The card writes to it. <\/p>\n<\/div>\n\n\n\n<h2 id=\"what-the-card-must-be\" class=\"wp-block-heading\">What the card must be<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Format the card as <strong>FAT32<\/strong>. Use any computer to format it and to copy files onto it.<\/p>\n\n\n\n<h2 id=\"folders-and-files\" class=\"wp-block-heading\">microSD Folders and files structure<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">The card looks for these files and folders in the root of the card:<\/p>\n\n\n\n<figure class=\"wp-block-table is-style-stripes\"><table><thead><tr><th>Path<\/th><th>Content<\/th><\/tr><\/thead><tbody><tr><td><code class=\"\" data-line=\"\">config.txt<\/code><\/td><td>Text configuration. Optional. See <a href=\"https:\/\/www.r3tr0.net\/index.php\/wondermca-documentation\/wmdoc_settings\/\">the configuration page<\/a><\/td><\/tr><tr><td><code class=\"\" data-line=\"\">WONDERMCA.CFG<\/code><\/td><td>Settings saved by the setup menu. The card creates it. Do not edit it manually<\/td><\/tr><tr><td><code class=\"\" data-line=\"\">wifi.txt<\/code><\/td><td>The WiFi name and password. See <a href=\"https:\/\/www.r3tr0.net\/index.php\/wondermca-documentation\/wmdoc_network\/\">Network<\/a><\/td><\/tr><tr><td><code class=\"\" data-line=\"\">HDD\/<\/code><\/td><td>Hard disk images, <code class=\"\" data-line=\"\">.img<\/code> files and fixed <code class=\"\" data-line=\"\">.vhd<\/code> files. An optional <code class=\"\" data-line=\"\">.chs<\/code> file with the same name sets the geometry<\/td><\/tr><tr><td><code class=\"\" data-line=\"\">FLOPPY\/<\/code><\/td><td>Floppy images, <code class=\"\" data-line=\"\">.img<\/code> files<\/td><\/tr><tr><td><code class=\"\" data-line=\"\">CDROM\/<\/code><\/td><td>CD-ROM images, <code class=\"\" data-line=\"\">.iso<\/code> and <code class=\"\" data-line=\"\">.cue<\/code> files<\/td><\/tr><tr><td><code class=\"\" data-line=\"\">ROM\/<\/code><\/td><td>Option ROM files. Not used in normal operation<\/td><\/tr><tr><td><code class=\"\" data-line=\"\">UPGRADE\/<\/code><\/td><td>CPLD update files. See <a href=\"https:\/\/www.r3tr0.net\/index.php\/wondermca-documentation\/wmdoc_firmware-cpld-update\/\">Firmware and CPLD update<\/a><\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">You can create sub-folders inside <code class=\"\" data-line=\"\">HDD<\/code>, <code class=\"\" data-line=\"\">FLOPPY<\/code> and <code class=\"\" data-line=\"\">CDROM<\/code>. The setup menu and the screenpad open them. A good layout keeps one folder per system or per game set, for example <code class=\"\" data-line=\"\">FLOPPY\\OS2<\/code> for the OS\/2 install diskettes and <code class=\"\" data-line=\"\">FLOPPY\\GAMES<\/code> for games.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Which image is mounted on which drive is chosen in the setup menu or on the screenpad, not in <code class=\"\" data-line=\"\">config.txt<\/code>. The card keeps your choice in <code class=\"\" data-line=\"\">WONDERMCA.CFG<\/code>.<\/p>\n\n\n\n<div class=\"wp-block-group wmdoc-callout wmdoc-note has-background is-layout-constrained wp-container-core-group-is-layout-1828d0e2 wp-block-group-is-layout-constrained\" style=\"border-radius:6px;border-left-color:#f0b429;border-left-style:solid;border-left-width:4px;background-color:#fff8e1;margin-top:24px;margin-bottom:24px;padding-top:12px;padding-right:20px;padding-bottom:12px;padding-left:20px\">\n<p class=\"wp-block-paragraph\"><strong>Note.<\/strong> If you delete <code class=\"\" data-line=\"\">WONDERMCA.CFG<\/code>, the card starts with its default settings and writes a new file. do not edit this file manually<\/p>\n<\/div>\n\n\n\n<h2 id=\"rules-for-image-names\" class=\"wp-block-heading\">Rules for image names<\/h2>\n\n\n\n<figure class=\"wp-block-table is-style-stripes\"><table><thead><tr><th>Rule<\/th><th>Detail<\/th><\/tr><\/thead><tbody><tr><td>Extension<\/td><td>Floppy and hard disk images end in <code class=\"\" data-line=\"\">.img<\/code>. A hard disk image can also be a fixed <code class=\"\" data-line=\"\">.vhd<\/code>. CD images end in <code class=\"\" data-line=\"\">.iso<\/code> or <code class=\"\" data-line=\"\">.cue<\/code><\/td><\/tr><tr><td>Length<\/td><td>The name before the extension has <strong>13 characters at most<\/strong><\/td><\/tr><tr><td>Case<\/td><td>Upper and lower case both work<\/td><\/tr><tr><td>Size of a floppy image<\/td><td>160 KB to 2880 KB. A file outside this range is not listed<\/td><\/tr><tr><td>Size of a hard disk image<\/td><td>2 MB to 4096 MB. A file outside this range is not listed<\/td><\/tr><tr><td>Size of a CD image<\/td><td>900 MB at most. A larger file is not listed<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Why 13 characters.<\/strong> The card saves the name of each mounted image in 13 characters. A longer name is cut when it is saved, and at the next start the card looks for a file that does not exist: the mount fails, the boot banner lists the image with <strong>Image not found<\/strong> and the red LED of the screenpad blinks. The setup menu shows <strong>Error<\/strong> as the size of such a file and refuses it. Rename the file to 13 characters or less. <code class=\"\" data-line=\"\">WARP3_DISK1<\/code> is fine, <code class=\"\" data-line=\"\">WARP3_INSTALL_DISK1<\/code> is not.<\/p>\n\n\n\n<figure class=\"wp-block-gallery has-nested-images columns-2 wp-block-gallery-1 is-layout-flex wp-block-gallery-is-layout-flex\" style=\"margin-top:24px;margin-bottom:24px\">\n<figure class=\"wp-block-image size-full has-custom-border\"><img loading=\"lazy\" decoding=\"async\" width=\"512\" height=\"256\" data-id=\"1201\" src=\"https:\/\/www.r3tr0.net\/wp-content\/uploads\/2026\/10\/wm_screenpad_mount_picker_name_16chars.png\" alt=\"The floppy picker of the screenpad on a 16-character name: the row shows the first 15 characters\" class=\"wp-image-1201\" style=\"border-radius:6px\" srcset=\"https:\/\/www.r3tr0.net\/wp-content\/uploads\/2026\/10\/wm_screenpad_mount_picker_name_16chars.png 512w, https:\/\/www.r3tr0.net\/wp-content\/uploads\/2026\/10\/wm_screenpad_mount_picker_name_16chars-300x150.png 300w\" sizes=\"auto, (max-width: 512px) 100vw, 512px\" \/><figcaption class=\"wp-element-caption\">The floppy picker of the screenpad on a 16-character name: the row shows the first 15 characters<\/figcaption><\/figure>\n\n\n\n<figure class=\"wp-block-image size-full has-custom-border\"><img loading=\"lazy\" decoding=\"async\" width=\"512\" height=\"256\" data-id=\"1202\" src=\"https:\/\/www.r3tr0.net\/wp-content\/uploads\/2026\/10\/wm_screenpad_mount_picker_name_16chars_later.png\" alt=\"The same row a moment later: the name has scrolled sideways to show its end\" class=\"wp-image-1202\" style=\"border-radius:6px\" srcset=\"https:\/\/www.r3tr0.net\/wp-content\/uploads\/2026\/10\/wm_screenpad_mount_picker_name_16chars_later.png 512w, https:\/\/www.r3tr0.net\/wp-content\/uploads\/2026\/10\/wm_screenpad_mount_picker_name_16chars_later-300x150.png 300w\" sizes=\"auto, (max-width: 512px) 100vw, 512px\" \/><figcaption class=\"wp-element-caption\">The same row a moment later: the name has scrolled sideways to show its end<\/figcaption><\/figure>\n<\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">The lists are sorted by name, without regard to case, and numbers count as numbers: <code class=\"\" data-line=\"\">DISK2<\/code> comes before <code class=\"\" data-line=\"\">DISK10<\/code>. Folders come first. A list holds 128 entries at most. In the setup menu a page shows 16 entries, and on the screenpad a page shows 5 rows.<\/p>\n\n\n\n<h2 id=\"the-usb-stick\" class=\"wp-block-heading\">The USB stick<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">A USB mass-storage device plugged into the USB-A port is seen as a second volume. It has its own <code class=\"\" data-line=\"\">FLOPPY<\/code> and <code class=\"\" data-line=\"\">HDD<\/code> folders, like the microSD card. CD images are read from the microSD card only.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">When you browse images, the top of the list shows <strong>[SD]<\/strong> and, when a stick is plugged in, <strong>[USB]<\/strong>. Choose one to open its folders. The entry <code class=\"\" data-line=\"\">..<\/code> goes up one level, and at the top of a volume it returns to the choice of the volume.<\/p>\n\n\n\n<figure class=\"wp-block-image aligncenter size-full is-resized has-custom-border\"><img loading=\"lazy\" decoding=\"async\" width=\"720\" height=\"400\" src=\"https:\/\/www.r3tr0.net\/wp-content\/uploads\/2026\/10\/wm_bios_setup_disk_fdd_root.png\" alt=\"The floppy list of the setup menu, first view: the entry -=None=- and the volume [SD]\" class=\"wp-image-1112\" style=\"border-radius:6px;width:560px;height:auto\" srcset=\"https:\/\/www.r3tr0.net\/wp-content\/uploads\/2026\/10\/wm_bios_setup_disk_fdd_root.png 720w, https:\/\/www.r3tr0.net\/wp-content\/uploads\/2026\/10\/wm_bios_setup_disk_fdd_root-300x167.png 300w, https:\/\/www.r3tr0.net\/wp-content\/uploads\/2026\/10\/wm_bios_setup_disk_fdd_root-600x333.png 600w\" sizes=\"auto, (max-width: 720px) 100vw, 720px\" \/><figcaption class=\"wp-element-caption\">The floppy list of the setup menu, first view: the entry -=None=- and the volume [SD]<\/figcaption><\/figure>\n\n\n\n<figure class=\"wp-block-image aligncenter size-full is-resized has-custom-border\"><img loading=\"lazy\" decoding=\"async\" width=\"720\" height=\"400\" src=\"https:\/\/www.r3tr0.net\/wp-content\/uploads\/2026\/10\/wm_bios_setup_disk_fdd_root_usb.png\" alt=\"The same list with a USB stick plugged in: [SD] and [USB]\" class=\"wp-image-1113\" style=\"border-radius:6px;width:560px;height:auto\" srcset=\"https:\/\/www.r3tr0.net\/wp-content\/uploads\/2026\/10\/wm_bios_setup_disk_fdd_root_usb.png 720w, https:\/\/www.r3tr0.net\/wp-content\/uploads\/2026\/10\/wm_bios_setup_disk_fdd_root_usb-300x167.png 300w, https:\/\/www.r3tr0.net\/wp-content\/uploads\/2026\/10\/wm_bios_setup_disk_fdd_root_usb-600x333.png 600w\" sizes=\"auto, (max-width: 720px) 100vw, 720px\" \/><figcaption class=\"wp-element-caption\">The same list with a USB stick plugged in: [SD] and [USB]<\/figcaption><\/figure>\n\n\n\n<figure class=\"wp-block-image aligncenter size-full is-resized has-custom-border\"><img loading=\"lazy\" decoding=\"async\" width=\"512\" height=\"256\" src=\"https:\/\/www.r3tr0.net\/wp-content\/uploads\/2026\/10\/wm_screenpad_mount_picker_root.png\" alt=\"The floppy picker of the screenpad, first view: [SD] and [USB]\" class=\"wp-image-1203\" style=\"border-radius:6px;width:256px;height:auto\" srcset=\"https:\/\/www.r3tr0.net\/wp-content\/uploads\/2026\/10\/wm_screenpad_mount_picker_root.png 512w, https:\/\/www.r3tr0.net\/wp-content\/uploads\/2026\/10\/wm_screenpad_mount_picker_root-300x150.png 300w\" sizes=\"auto, (max-width: 512px) 100vw, 512px\" \/><figcaption class=\"wp-element-caption\">The floppy picker of the screenpad, first view: [SD] and [USB]<\/figcaption><\/figure>\n\n\n\n<figure class=\"wp-block-image aligncenter size-full is-resized has-custom-border\"><img loading=\"lazy\" decoding=\"async\" width=\"512\" height=\"256\" src=\"https:\/\/www.r3tr0.net\/wp-content\/uploads\/2026\/10\/wm_screenpad_mount_picker_root_sd_only.png\" alt=\"The same picker with no USB stick: [SD] only\" class=\"wp-image-1204\" style=\"border-radius:6px;width:256px;height:auto\" srcset=\"https:\/\/www.r3tr0.net\/wp-content\/uploads\/2026\/10\/wm_screenpad_mount_picker_root_sd_only.png 512w, https:\/\/www.r3tr0.net\/wp-content\/uploads\/2026\/10\/wm_screenpad_mount_picker_root_sd_only-300x150.png 300w\" sizes=\"auto, (max-width: 512px) 100vw, 512px\" \/><figcaption class=\"wp-element-caption\">The same picker with no USB stick: [SD] only<\/figcaption><\/figure>\n\n\n\n<figure class=\"wp-block-image aligncenter size-full is-resized has-custom-border\"><img loading=\"lazy\" decoding=\"async\" width=\"512\" height=\"256\" src=\"https:\/\/www.r3tr0.net\/wp-content\/uploads\/2026\/10\/wm_screenpad_mount_picker_root_usb.png\" alt=\"The same picker with the cursor on [USB]\" class=\"wp-image-1205\" style=\"border-radius:6px;width:256px;height:auto\" srcset=\"https:\/\/www.r3tr0.net\/wp-content\/uploads\/2026\/10\/wm_screenpad_mount_picker_root_usb.png 512w, https:\/\/www.r3tr0.net\/wp-content\/uploads\/2026\/10\/wm_screenpad_mount_picker_root_usb-300x150.png 300w\" sizes=\"auto, (max-width: 512px) 100vw, 512px\" \/><figcaption class=\"wp-element-caption\">The same picker with the cursor on [USB]<\/figcaption><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">Inside a volume, a folder opens with <strong>Enter<\/strong> or <strong>ENTER<\/strong>. In the setup menu a folder shows in square brackets, such as <code class=\"\" data-line=\"\">[OS2]<\/code>:<\/p>\n\n\n\n<figure class=\"wp-block-image aligncenter size-full is-resized has-custom-border\"><img loading=\"lazy\" decoding=\"async\" width=\"720\" height=\"400\" src=\"https:\/\/www.r3tr0.net\/wp-content\/uploads\/2026\/10\/wm_bios_setup_disk_fdd_folder.png\" alt=\"The floppy list of the setup menu inside the folder OS2 of the microSD card: [..] then the images of the folder\" class=\"wp-image-1106\" style=\"border-radius:6px;width:560px;height:auto\" srcset=\"https:\/\/www.r3tr0.net\/wp-content\/uploads\/2026\/10\/wm_bios_setup_disk_fdd_folder.png 720w, https:\/\/www.r3tr0.net\/wp-content\/uploads\/2026\/10\/wm_bios_setup_disk_fdd_folder-300x167.png 300w, https:\/\/www.r3tr0.net\/wp-content\/uploads\/2026\/10\/wm_bios_setup_disk_fdd_folder-600x333.png 600w\" sizes=\"auto, (max-width: 720px) 100vw, 720px\" \/><figcaption class=\"wp-element-caption\">The floppy list of the setup menu inside the folder OS2 of the microSD card: [..] then the images of the folder<\/figcaption><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">The setup menu and the screenpad keep which volume an image came from. See <a href=\"https:\/\/www.r3tr0.net\/index.php\/wondermca-documentation\/wmdoc_disks\/\">Hard disks and floppy disks<\/a>.<\/p>\n\n\n\n<h2 id=\"files-the-card-writes\" class=\"wp-block-heading\">Files the card writes<\/h2>\n\n\n\n<figure class=\"wp-block-table is-style-stripes\"><table><thead><tr><th>File<\/th><th>When<\/th><\/tr><\/thead><tbody><tr><td><code class=\"\" data-line=\"\">WONDERMCA.CFG<\/code><\/td><td>At every start of the option ROM (after the setup menu), when you mount or eject an image on the screenpad, and when <code class=\"\" data-line=\"\">wmctrl<\/code> saves<\/td><\/tr><tr><td><code class=\"\" data-line=\"\">HDD\/&lt;name&gt;.img<\/code><\/td><td>When you create a new hard disk image<\/td><\/tr><tr><td><code class=\"\" data-line=\"\">ROM_&lt;address&gt;.BIN<\/code> and <code class=\"\" data-line=\"\">RAM_DUMP.BIN<\/code><\/td><td>When you run <strong>ROM\/RAM Dump<\/strong> on the <strong>Tools<\/strong> page of the setup menu<\/td><\/tr><tr><td><code class=\"\" data-line=\"\">UPGRADE\/cpld_upgrade.log<\/code><\/td><td>At every CPLD update, rewritten each time<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<h2 id=\"when-the-card-cannot-be-read\" class=\"wp-block-heading\">When the card cannot be read<\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li>The boot banner shows <strong>MicroSD : Fail<\/strong>. USB is then reported <strong>Disabled<\/strong> and no image is listed. See <a href=\"https:\/\/www.r3tr0.net\/index.php\/wondermca-documentation\/wmdoc_troubleshooting\/\">Troubleshooting<\/a>.<\/li>\n<\/ul>\n\n\n\n<figure class=\"wp-block-image aligncenter size-full is-resized has-custom-border\"><img loading=\"lazy\" decoding=\"async\" width=\"720\" height=\"400\" src=\"https:\/\/www.r3tr0.net\/wp-content\/uploads\/2026\/10\/wm_bios_boot_error_no_sd.png\" alt=\"The boot banner with the microSD card missing: &quot;MicroSD : Fail&quot;\" class=\"wp-image-1085\" style=\"border-radius:6px;width:560px;height:auto\" srcset=\"https:\/\/www.r3tr0.net\/wp-content\/uploads\/2026\/10\/wm_bios_boot_error_no_sd.png 720w, https:\/\/www.r3tr0.net\/wp-content\/uploads\/2026\/10\/wm_bios_boot_error_no_sd-300x167.png 300w, https:\/\/www.r3tr0.net\/wp-content\/uploads\/2026\/10\/wm_bios_boot_error_no_sd-600x333.png 600w\" sizes=\"auto, (max-width: 720px) 100vw, 720px\" \/><figcaption class=\"wp-element-caption\">The boot banner with the microSD card missing: &#8220;MicroSD : Fail&#8221;<\/figcaption><\/figure>\n\n\n\n<ul class=\"wp-block-list\">\n<li>The <strong>Disk<\/strong> page of the setup menu shows <strong>Warning: SD not present or error<\/strong> and every drive shows <strong>-=None=-<\/strong>.<\/li>\n<\/ul>\n\n\n\n<figure class=\"wp-block-image aligncenter size-full is-resized has-custom-border\"><img loading=\"lazy\" decoding=\"async\" width=\"720\" height=\"400\" src=\"https:\/\/www.r3tr0.net\/wp-content\/uploads\/2026\/10\/wm_bios_setup_disk_sd_error.png\" alt=\"The Disk page of the setup menu with the warning &quot;SD not present or error&quot;\" class=\"wp-image-1118\" style=\"border-radius:6px;width:560px;height:auto\" srcset=\"https:\/\/www.r3tr0.net\/wp-content\/uploads\/2026\/10\/wm_bios_setup_disk_sd_error.png 720w, https:\/\/www.r3tr0.net\/wp-content\/uploads\/2026\/10\/wm_bios_setup_disk_sd_error-300x167.png 300w, https:\/\/www.r3tr0.net\/wp-content\/uploads\/2026\/10\/wm_bios_setup_disk_sd_error-600x333.png 600w\" sizes=\"auto, (max-width: 720px) 100vw, 720px\" \/><figcaption class=\"wp-element-caption\">The Disk page of the setup menu with the warning &#8220;SD not present or error&#8221;<\/figcaption><\/figure>\n\n\n\n<ul class=\"wp-block-list\">\n<li>If a configured image is missing, the boot banner lists its name with the reason in brackets: <strong>No FLOPPY folder<\/strong>, <strong>No HDD folder<\/strong>, <strong>Image not found<\/strong> or <strong>Bad image<\/strong>.<\/li>\n<\/ul>\n\n\n\n<figure class=\"wp-block-image aligncenter size-full is-resized has-custom-border\"><img loading=\"lazy\" decoding=\"async\" width=\"720\" height=\"400\" src=\"https:\/\/www.r3tr0.net\/wp-content\/uploads\/2026\/10\/wm_bios_boot_banner_mount_error.png\" alt=\"The boot banner with two images that cannot be mounted: FDD0 and HDD1 show &quot;Image not found&quot; in place of the size\" class=\"wp-image-1080\" style=\"border-radius:6px;width:560px;height:auto\" srcset=\"https:\/\/www.r3tr0.net\/wp-content\/uploads\/2026\/10\/wm_bios_boot_banner_mount_error.png 720w, https:\/\/www.r3tr0.net\/wp-content\/uploads\/2026\/10\/wm_bios_boot_banner_mount_error-300x167.png 300w, https:\/\/www.r3tr0.net\/wp-content\/uploads\/2026\/10\/wm_bios_boot_banner_mount_error-600x333.png 600w\" sizes=\"auto, (max-width: 720px) 100vw, 720px\" \/><figcaption class=\"wp-element-caption\">The boot banner with two images that cannot be mounted: FDD0 and HDD1 show &#8220;Image not found&#8221; in place of the size<\/figcaption><\/figure>\n\n\n\n<ul class=\"wp-block-list\">\n<li>If the settings could not be saved when you left the setup menu, the banner prints <strong>! Config File Write Error: Check\/Replace the MicroSD<\/strong>. The card goes on with the settings it has in memory. Check that the card is not write-protected and not full, or replace it.<\/li>\n<\/ul>\n\n\n\n<figure class=\"wp-block-image aligncenter size-full is-resized has-custom-border\"><img loading=\"lazy\" decoding=\"async\" width=\"720\" height=\"400\" src=\"https:\/\/www.r3tr0.net\/wp-content\/uploads\/2026\/10\/wm_bios_boot_error_config_write.png\" alt=\"The boot banner with the line &quot;! Config File Write Error: Check\/Replace the MicroSD&quot;\" class=\"wp-image-1083\" style=\"border-radius:6px;width:560px;height:auto\" srcset=\"https:\/\/www.r3tr0.net\/wp-content\/uploads\/2026\/10\/wm_bios_boot_error_config_write.png 720w, https:\/\/www.r3tr0.net\/wp-content\/uploads\/2026\/10\/wm_bios_boot_error_config_write-300x167.png 300w, https:\/\/www.r3tr0.net\/wp-content\/uploads\/2026\/10\/wm_bios_boot_error_config_write-600x333.png 600w\" sizes=\"auto, (max-width: 720px) 100vw, 720px\" \/><figcaption class=\"wp-element-caption\">The boot banner with the line &#8220;! Config File Write Error: Check\/Replace the MicroSD&#8221;<\/figcaption><\/figure>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity is-style-wide\" style=\"margin-top:48px;margin-bottom:24px\"\/>\n\n\n\n<div class=\"wp-block-columns is-layout-flex wp-container-core-columns-is-layout-7387b849 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\">\n<div class=\"wp-block-group has-background is-layout-constrained wp-container-core-group-is-layout-0ee9f569 wp-block-group-is-layout-constrained\" style=\"border-radius:8px;background-color:#f6f7f7;padding-top:14px;padding-right:18px;padding-bottom:14px;padding-left:18px\">\n<p class=\"has-text-align-left has-text-color wp-block-paragraph\" style=\"color:#0f62fe;margin-bottom:2px;font-size:12px;font-weight:600;letter-spacing:2px;text-transform:uppercase\">\u2190 Previous<\/p>\n\n\n\n<p class=\"has-text-align-left wp-block-paragraph\" style=\"margin-top:0;font-size:17px;font-weight:600\"><a href=\"https:\/\/www.r3tr0.net\/index.php\/wondermca-documentation\/wmdoc_hardware-installation\/\">Hardware and installation<\/a><\/p>\n<\/div>\n<\/div>\n\n\n\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\">\n<div class=\"wp-block-group has-background is-layout-constrained wp-container-core-group-is-layout-0ee9f569 wp-block-group-is-layout-constrained\" style=\"border-radius:8px;background-color:#f6f7f7;padding-top:14px;padding-right:18px;padding-bottom:14px;padding-left:18px\">\n<p class=\"has-text-align-right has-text-color wp-block-paragraph\" style=\"color:#0f62fe;margin-bottom:2px;font-size:12px;font-weight:600;letter-spacing:2px;text-transform:uppercase\">Next \u2192<\/p>\n\n\n\n<p class=\"has-text-align-right wp-block-paragraph\" style=\"margin-top:0;font-size:17px;font-weight:600\"><a href=\"https:\/\/www.r3tr0.net\/index.php\/wondermca-documentation\/wmdoc_firmware-cpld-update\/\">Firmware and CPLD update<\/a><\/p>\n<\/div>\n<\/div>\n<\/div>\n\n\n\n<p class=\"has-text-align-center has-text-color wp-block-paragraph\" style=\"color:#787c82;margin-top:20px;font-size:13px\">WonderMCA user documentation  \u00b7 <a href=\"https:\/\/www.r3tr0.net\/index.php\/wondermca-documentation\/\">Documentation home<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>What the microSD card must be, the folders and files the card looks for, the rules for image names, how the lists of the setup menu and of the screenpad show the card and a USB stick, the files the card writes itself, and the messages when the card cannot be read.<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":1277,"menu_order":3,"comment_status":"closed","ping_status":"closed","template":"","meta":{"site-sidebar-layout":"no-sidebar","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center 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center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"footnotes":""},"tags":[49,33,32,34,50],"class_list":["post-1279","page","type-page","status-publish","hentry","tag-documentation","tag-ibm","tag-mca","tag-ps-2","tag-wondermca"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v28.7 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>WonderMCA: The microSD card - R3TR0<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.r3tr0.net\/index.php\/wondermca-documentation\/wmdoc_sd-card\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"WonderMCA: The microSD card - R3TR0\" \/>\n<meta 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