diff --git a/src/arch/kim-1/cpmfs/imu.txt b/src/arch/kim-1/cpmfs/imu.txt
index 77df50fa..bc08c3fc 100644
--- a/src/arch/kim-1/cpmfs/imu.txt
+++ b/src/arch/kim-1/cpmfs/imu.txt
@@ -1,7 +1,7 @@
 Image Manipulation Utility
 ==========================
 
-Usage:  imu [/L]
+Usage:  imu [{/L | /S}]
         imu /M <drive> <image> [/O]
         imu /U <drive>
         imu /N <image> [/P]
@@ -15,6 +15,8 @@ Options
 
 /L      - Lists the available disk images on the SD card.
 
+/S      - Saves the current mounts to the SD card config file.
+
 /M <drive> <image> [/O]
         - Mounts <image> into <drive>. Option /O makes it read-only.
 
diff --git a/src/arch/kim-1/k-1013.inc b/src/arch/kim-1/k-1013.inc
index 6e316c2b..69072185 100644
--- a/src/arch/kim-1/k-1013.inc
+++ b/src/arch/kim-1/k-1013.inc
@@ -35,6 +35,7 @@ EXT_CMD_CPY         = 0b00011000
 EXT_CMD_MOV         = 0b00011100
 EXT_CMD_MNT         = 0b00100000
 EXT_CMD_UMNT        = 0b00100100
+EXT_CMD_SAV         = 0b00101000
 
 ST4_UNSUPPORTED     = 0b10000000
 ST4_ABNORMAL_TERM   = 0b01000000
diff --git a/src/arch/kim-1/utils/imu-k1013.S b/src/arch/kim-1/utils/imu-k1013.S
index 16b5a0a9..1338aac4 100644
--- a/src/arch/kim-1/utils/imu-k1013.S
+++ b/src/arch/kim-1/utils/imu-k1013.S
@@ -291,6 +291,7 @@ zproc unmount_drive
     
     ; Dig further for errors
 
+    lda disk_status                 ; Check for success
     and #ST4_ABNORMAL_TERM
     zif ne
         lda disk_status+1
@@ -314,13 +315,29 @@ zproc unmount_drive
     jmp inf_done
 zendproc
 
-; Update config to flash. Not yet supported
+; Update the SD config file with the latest mounted drives
+; situation. Issues warning if the file could not be
+; updated.
 ;
 zproc save_config
-    lda #<unknown_msg
-    ldy #>unknown_msg
-    jsr err_withchar
-    jmp err_usage
+
+    ldy #EXT_CMD_SAV
+    jsr fdc_exec_extended           ; Exec SD mounts config save
+    zif cs
+        lda #<fdc_msg
+        ldx #>fdc_msg
+        jmp err_withmsg             ; Controller error
+    zendif
+
+    lda disk_status                 ; Check for success
+    and #ST4_ABNORMAL_TERM
+    zif ne
+        lda #<config_msg
+        ldx #>config_msg
+        jmp err_withmsg
+    zendif
+
+    jmp inf_done
 zendproc
 
 ; Create an empty image on the SD card.
@@ -376,7 +393,7 @@ zproc create_image
 
     ; Set buffer for sending mount info
 
-    lda #BUFFER_DMA
+    lda #DMA_AREA
     sta ADMA
 
     ; Prepare the command data
@@ -425,7 +442,7 @@ zproc create_image
         zendif
         ; If we are here, there was an unexpected error
         lda #<generic_msg
-        ldy #>generic_msg
+        ldx #>generic_msg
         jmp err_withmsg
     zendif
 
@@ -493,7 +510,7 @@ zproc delete_file
         zendif
         ; If we are here, there was an unexpected error
         lda #<generic_msg
-        ldy #>generic_msg
+        ldx #>generic_msg
         jmp err_withmsg
     zendif
 
@@ -741,7 +758,7 @@ disk_status:    .fill 8             ; Result phase readouts from NEC-765
 
     .global usage_msg
 
-usage_msg:      .ascii "Usage: imu [/L]\r\n"
+usage_msg:      .ascii "Usage: imu [{/L | /S}]\r\n"
                 .ascii "       imu /M <drive> [/O]\r\n"
                 .ascii "       imu /U <drive>\r\n"
                 .ascii "       imu /N <image> [/P]\r\n"
diff --git a/src/arch/kim-1/utils/imu-sdshield.S b/src/arch/kim-1/utils/imu-sdshield.S
index 6effb7c6..c4dcd60d 100644
--- a/src/arch/kim-1/utils/imu-sdshield.S
+++ b/src/arch/kim-1/utils/imu-sdshield.S
@@ -609,8 +609,5 @@ imagerr_msg:    .ascii "Image name must be in 8.3 format.\r\n"
 disabled_msg:   .ascii "Disabled by hardware. Please flip option switch 2.\r\n"
                 .byte 0
 
-config_msg:     .ascii "Can't update the SD config file.\r\n"
-                .byte 0
-
 working_msg:    .ascii "On it. May take a while...\r\n"
                 .byte 0
diff --git a/src/arch/kim-1/utils/imu.S b/src/arch/kim-1/utils/imu.S
index aaebbcb5..b4119bde 100644
--- a/src/arch/kim-1/utils/imu.S
+++ b/src/arch/kim-1/utils/imu.S
@@ -481,6 +481,7 @@ zendproc
 
     .global unknown_msg, invalid_msg, mounterr_msg, mountederr_msg
     .global unmnterr_msg, notmntederr_msg, generic_msg, exists_msg
+    .global config_msg
 
 error_msg:      .ascii "Error: "
                 .byte 0
@@ -531,6 +532,9 @@ imgmounted_msg: .ascii "Error: Image file '"
 imgmounted_msg2:.ascii "' already mounted.\r\n"
                 .byte 0
 
+config_msg:     .ascii "Can't update the SD config file.\r\n"
+                .byte 0
+
 warning_msg:    .ascii "Warning: About to delete file '"
                 .byte 0
 warning_msg2:   .ascii "'.\r\n"