diff --git a/asminc/rp6502.inc b/asminc/rp6502.inc
index 816712abb..1d850ec80 100644
--- a/asminc/rp6502.inc
+++ b/asminc/rp6502.inc
@@ -34,9 +34,10 @@ RIA_OP_EXIT               := $FF
 RIA_OP_ZXSTACK            := $00
 RIA_OP_XREG               := $01
 RIA_OP_PHI2               := $02
-RIA_OP_CODEPAGE           := $03
+RIA_OP_CODE_PAGE          := $03
 RIA_OP_LRAND              := $04
 RIA_OP_STDIN_OPT          := $05
+RIA_OP_ERRNO_OPT          := $06
 RIA_OP_CLOCK              := $0F
 RIA_OP_CLOCK_GETRES       := $10
 RIA_OP_CLOCK_GETTIME      := $11
@@ -49,8 +50,27 @@ RIA_OP_READ_XRAM          := $17
 RIA_OP_WRITE_XSTACK       := $18
 RIA_OP_WRITE_XRAM         := $19
 RIA_OP_LSEEK              := $1A
+RIA_OP_LSEEK_CC65         := $1A
 RIA_OP_UNLINK             := $1B
 RIA_OP_RENAME             := $1C
+RIA_OP_LSEEK_LLVM         := $1D
+RIA_OP_SYNCFS             := $1E
+RIA_OP_STAT               := $1F
+RIA_OP_OPENDIR            := $20
+RIA_OP_READDIR            := $21
+RIA_OP_CLOSEDIR           := $22
+RIA_OP_TELLDIR            := $23
+RIA_OP_SEEKDIR            := $24
+RIA_OP_REWINDDIR          := $25
+RIA_OP_CHMOD              := $26
+RIA_OP_UTIME              := $27
+RIA_OP_MKDIR              := $28
+RIA_OP_CHDIR              := $29
+RIA_OP_CHDRIVE            := $2A
+RIA_OP_GETCWD             := $2B
+RIA_OP_SETLABEL           := $2C
+RIA_OP_GETLABEL           := $2D
+RIA_OP_GETFREE            := $2E
 
 ; 6522 VIA
 VIA             := $FFD0        ; VIA base address
@@ -72,27 +92,3 @@ VIA_PCR         := VIA+$C       ; Peripheral control register
 VIA_IFR         := VIA+$D       ; Interrupt flag register
 VIA_IER         := VIA+$E       ; Interrupt enable register
 VIA_PA2         := VIA+$F       ; Port register A w/o handshake
-
-; Values in ___oserror are the union of these FatFs errors and errno.inc
-.enum
-    FR_OK = 32             ; Succeeded
-    FR_DISK_ERR            ; A hard error occurred in the low level disk I/O layer
-    FR_INT_ERR             ; Assertion failed
-    FR_NOT_READY           ; The physical drive cannot work
-    FR_NO_FILE             ; Could not find the file
-    FR_NO_PATH             ; Could not find the path
-    FR_INVALID_NAME        ; The path name format is invalid
-    FR_DENIED              ; Access denied due to prohibited access or directory full
-    FR_EXIST               ; Access denied due to prohibited access
-    FR_INVALID_OBJECT      ; The file/directory object is invalid
-    FR_WRITE_PROTECTED     ; The physical drive is write protected
-    FR_INVALID_DRIVE       ; The logical drive number is invalid
-    FR_NOT_ENABLED         ; The volume has no work area
-    FR_NO_FILESYSTEM       ; There is no valid FAT volume
-    FR_MKFS_ABORTED        ; The f_mkfs() aborted due to any problem
-    FR_TIMEOUT             ; Could not get a grant to access the volume within defined period
-    FR_LOCKED              ; The operation is rejected according to the file sharing policy
-    FR_NOT_ENOUGH_CORE     ; LFN working buffer could not be allocated
-    FR_TOO_MANY_OPEN_FILES ; Number of open files > FF_FS_LOCK
-    FR_INVALID_PARAMETER   ; Given parameter is invalid
-.endenum
diff --git a/include/rp6502.h b/include/rp6502.h
index 7deeebc4c..2c0e78b87 100644
--- a/include/rp6502.h
+++ b/include/rp6502.h
@@ -47,7 +47,7 @@ struct __RP6502
     unsigned char step1;
     unsigned int addr1;
     unsigned char xstack;
-    unsigned int errno;
+    unsigned int errno_;
     unsigned char op;
     unsigned char irq;
     const unsigned char spin;
@@ -86,20 +86,16 @@ void __fastcall__ ria_set_ax (unsigned int ax);
 int __fastcall__ ria_call_int (unsigned char op);
 long __fastcall__ ria_call_long (unsigned char op);
 
-/* These run _mappederrno() on error */
-
-int __fastcall__ ria_call_int_errno (unsigned char op);
-long __fastcall__ ria_call_long_errno (unsigned char op);
-
 /* OS operation numbers */
 
 #define RIA_OP_EXIT 0xFF
 #define RIA_OP_ZXSTACK 0x00
 #define RIA_OP_XREG 0x01
 #define RIA_OP_PHI2 0x02
-#define RIA_OP_CODEPAGE 0x03
+#define RIA_OP_CODE_PAGE 0x03
 #define RIA_OP_LRAND 0x04
 #define RIA_OP_STDIN_OPT 0x05
+#define RIA_OP_ERRNO_OPT 0x06
 #define RIA_OP_CLOCK 0x0F
 #define RIA_OP_CLOCK_GETRES 0x10
 #define RIA_OP_CLOCK_GETTIME 0x11
@@ -112,27 +108,78 @@ long __fastcall__ ria_call_long_errno (unsigned char op);
 #define RIA_OP_WRITE_XSTACK 0x18
 #define RIA_OP_WRITE_XRAM 0x19
 #define RIA_OP_LSEEK 0x1A
+#define RIA_OP_LSEEK_CC65 0x1A
 #define RIA_OP_UNLINK 0x1B
 #define RIA_OP_RENAME 0x1C
+#define RIA_OP_LSEEK_LLVM 0x1D
+#define RIA_OP_SYNCFS 0x1E
+#define RIA_OP_STAT 0x1F
+#define RIA_OP_OPENDIR 0x20
+#define RIA_OP_READDIR 0x21
+#define RIA_OP_CLOSEDIR 0x22
+#define RIA_OP_TELLDIR 0x23
+#define RIA_OP_SEEKDIR 0x24
+#define RIA_OP_REWINDDIR 0x25
+#define RIA_OP_CHMOD 0x26
+#define RIA_OP_UTIME 0x27
+#define RIA_OP_MKDIR 0x28
+#define RIA_OP_CHDIR 0x29
+#define RIA_OP_CHDRIVE 0x2A
+#define RIA_OP_GETCWD 0x2B
+#define RIA_OP_SETLABEL 0x2C
+#define RIA_OP_GETLABEL 0x2D
+#define RIA_OP_GETFREE 0x2E
 
 /* C API for the operating system. */
 
+typedef struct {
+    unsigned long fsize;
+    unsigned fdate;
+    unsigned ftime;
+    unsigned crdate;
+    unsigned crtime;
+    unsigned char fattrib;
+    char altname[12 + 1];
+    char fname[255 + 1];
+} f_stat_t;
+
 int __cdecl__ xregn (char device, char channel, unsigned char address, unsigned count,
     ...);
 int __cdecl__ xreg (char device, char channel, unsigned char address, ...);
-int phi2 (void);
-int codepage (void);
-long lrand (void);
+int __fastcall__ phi2 (void);
+int __fastcall__ code_page (int);
+long __fastcall__ lrand (void);
 int __fastcall__ stdin_opt (unsigned long ctrl_bits, unsigned char str_length);
 int __fastcall__ read_xstack (void* buf, unsigned count, int fildes);
 int __fastcall__ read_xram (unsigned buf, unsigned count, int fildes);
 int __fastcall__ write_xstack (const void* buf, unsigned count, int fildes);
 int __fastcall__ write_xram (unsigned buf, unsigned count, int fildes);
+long __fastcall__ f_lseek (long offset, int whence, int fildes);
+int __fastcall__ f_stat (const char* path, f_stat_t* dirent);
+int __fastcall__ f_opendir (const char* name);
+int __fastcall__ f_readdir (f_stat_t* dirent, int dirdes);
+int __fastcall__ f_closedir (int dirdes);
+long __fastcall__ f_telldir (int dirdes);
+int __fastcall__ f_seekdir (long offs, int dirdes);
+int __fastcall__ f_rewinddir (int dirdes);
+int __fastcall__ f_chmod (const char* path, unsigned char attr, unsigned char mask);
+int __fastcall__ f_utime (const char* path, unsigned fdate, unsigned ftime, unsigned crdate, unsigned crtime);
+int __fastcall__ f_mkdir (const char* name);
+int __fastcall__ f_chdrive (const char* name);
+int __fastcall__ f_getcwd (char* name, int size);
+int __fastcall__ f_setlabel (const char* name);
+int __fastcall__ f_getlabel (const char* path, char* label);
+int __fastcall__ f_getfree (const char* name, unsigned long* free, unsigned long* total);
+
+/* Time zone hack */
+
+void ria_tzset (unsigned long time);
 
 /* XREG location helpers */
 
 #define xreg_ria_keyboard(...) xreg(0, 0, 0, __VA_ARGS__)
 #define xreg_ria_mouse(...) xreg(0, 0, 1, __VA_ARGS__)
+#define xreg_ria_gamepad(...) xreg(0, 0, 2, __VA_ARGS__)
 #define xreg_vga_canvas(...) xreg(1, 0, 0, __VA_ARGS__)
 #define xreg_vga_mode(...) xreg(1, 0, 1, __VA_ARGS__)
 
@@ -237,30 +284,4 @@ typedef struct
     unsigned char has_opacity_metadata; // bool
 } vga_mode4_asprite_t;
 
-/* Values in __oserror are the union of these FatFs errors and errno.h */
-
-typedef enum
-{
-    FR_OK = 32,             /* Succeeded */
-    FR_DISK_ERR,            /* A hard error occurred in the low level disk I/O layer */
-    FR_INT_ERR,             /* Assertion failed */
-    FR_NOT_READY,           /* The physical drive cannot work */
-    FR_NO_FILE,             /* Could not find the file */
-    FR_NO_PATH,             /* Could not find the path */
-    FR_INVALID_NAME,        /* The path name format is invalid */
-    FR_DENIED,              /* Access denied due to prohibited access or directory full */
-    FR_EXIST,               /* Access denied due to prohibited access */
-    FR_INVALID_OBJECT,      /* The file/directory object is invalid */
-    FR_WRITE_PROTECTED,     /* The physical drive is write protected */
-    FR_INVALID_DRIVE,       /* The logical drive number is invalid */
-    FR_NOT_ENABLED,         /* The volume has no work area */
-    FR_NO_FILESYSTEM,       /* There is no valid FAT volume */
-    FR_MKFS_ABORTED,        /* The f_mkfs() aborted due to any problem */
-    FR_TIMEOUT,             /* Could not get a grant to access the volume within defined period */
-    FR_LOCKED,              /* The operation is rejected according to the file sharing policy */
-    FR_NOT_ENOUGH_CORE,     /* LFN working buffer could not be allocated */
-    FR_TOO_MANY_OPEN_FILES, /* Number of open files > FF_FS_LOCK */
-    FR_INVALID_PARAMETER    /* Given parameter is invalid */
-} FRESULT;
-
 #endif /* _RP6502_H */
diff --git a/include/unistd.h b/include/unistd.h
index 05b60f1fd..d48fe6f31 100644
--- a/include/unistd.h
+++ b/include/unistd.h
@@ -77,6 +77,7 @@ extern int optind, opterr, optopt;
 int __fastcall__ write (int fd, const void* buf, unsigned count);
 int __fastcall__ read (int fd, void* buf, unsigned count);
 off_t __fastcall__ lseek (int fd, off_t offset, int whence);
+int __fastcall__ syncfs (int fd);
 int __fastcall__ unlink (const char* name);     /* Same as remove() */
 
 /* Directories */
@@ -98,6 +99,3 @@ int __fastcall__ exec (const char* progname, const char* cmdline);
 
 /* End of unistd.h */
 #endif
-
-
-
diff --git a/libsrc/rp6502/chdir.s b/libsrc/rp6502/chdir.s
new file mode 100644
index 000000000..bb467f671
--- /dev/null
+++ b/libsrc/rp6502/chdir.s
@@ -0,0 +1,14 @@
+;
+; Ullrich von Bassewitz, 2003-08-12
+;
+; int __fastcall__ chdir (const char* name);
+;
+
+        .export         _chdir
+
+        .import         __syschdir
+
+
+;--------------------------------------------------------------------------
+
+_chdir = __syschdir
diff --git a/libsrc/rp6502/close.c b/libsrc/rp6502/close.c
index dd7e38115..1981baaae 100644
--- a/libsrc/rp6502/close.c
+++ b/libsrc/rp6502/close.c
@@ -1,8 +1,8 @@
 #include <rp6502.h>
-#include <errno.h>
+#include <fcntl.h>
 
 int __fastcall__ close (int fd)
 {
     ria_set_ax (fd);
-    return ria_call_int_errno (RIA_OP_CLOSE);
+    return ria_call_int (RIA_OP_CLOSE);
 }
diff --git a/libsrc/rp6502/code_page.c b/libsrc/rp6502/code_page.c
new file mode 100644
index 000000000..b7baff27b
--- /dev/null
+++ b/libsrc/rp6502/code_page.c
@@ -0,0 +1,7 @@
+#include <rp6502.h>
+
+int __fastcall__ code_page (int cp)
+{
+    ria_set_ax (cp);
+    return ria_call_int (RIA_OP_CODE_PAGE);
+}
diff --git a/libsrc/rp6502/codepage.c b/libsrc/rp6502/codepage.c
deleted file mode 100644
index e28726f04..000000000
--- a/libsrc/rp6502/codepage.c
+++ /dev/null
@@ -1,6 +0,0 @@
-#include <rp6502.h>
-
-int __fastcall__ codepage (void)
-{
-    return ria_call_int (RIA_OP_CODEPAGE);
-}
diff --git a/libsrc/rp6502/crt0.s b/libsrc/rp6502/crt0.s
index 32d565fda..5cf63b615 100644
--- a/libsrc/rp6502/crt0.s
+++ b/libsrc/rp6502/crt0.s
@@ -46,6 +46,6 @@ _exit:
     sta RIA_A
     plx
     stx RIA_X
-    lda #$FF     ; exit()
+    lda #RIA_OP_EXIT
     sta RIA_OP
     stp
diff --git a/libsrc/rp6502/errno.s b/libsrc/rp6502/errno.s
new file mode 100644
index 000000000..a9a50afec
--- /dev/null
+++ b/libsrc/rp6502/errno.s
@@ -0,0 +1,25 @@
+;
+; 2003-08-12, Ullrich von Bassewitz
+; 2015-09-24, Greg King
+;
+; extern int __errno;
+; /* Library errors go here. */
+;
+
+        .include        "rp6502.inc"
+        .include        "errno.inc"
+        .export         ___errno
+        .import         _ria_call_int
+        .constructor    _errno_opt_constructor
+
+; The errno on the RIA is the errno for cc65
+___errno        := RIA_ERRNO
+
+.code
+
+; Request the RIA use cc65 values for RIA_ERRNO
+_errno_opt_constructor:
+        lda #$01 ; 1 = cc65
+        sta RIA_A
+        lda #RIA_OP_ERRNO_OPT
+        jmp _ria_call_int
diff --git a/libsrc/rp6502/f_chdrive.c b/libsrc/rp6502/f_chdrive.c
new file mode 100644
index 000000000..8a3b8f93a
--- /dev/null
+++ b/libsrc/rp6502/f_chdrive.c
@@ -0,0 +1,16 @@
+#include <rp6502.h>
+#include <errno.h>
+#include <string.h>
+
+int __fastcall__ f_chdrive (const char* name)
+{
+    size_t namelen = strlen (name);
+    if (namelen > 255) {
+        errno = EINVAL;
+        return -1;
+    }
+    while (namelen) {
+        ria_push_char (name[--namelen]);
+    }
+    return ria_call_int (RIA_OP_CHDRIVE);
+}
diff --git a/libsrc/rp6502/f_chmod.c b/libsrc/rp6502/f_chmod.c
new file mode 100644
index 000000000..7481cfb19
--- /dev/null
+++ b/libsrc/rp6502/f_chmod.c
@@ -0,0 +1,19 @@
+#include <rp6502.h>
+#include <errno.h>
+#include <string.h>
+
+int __fastcall__ f_chmod (const char* path, unsigned char attr, unsigned char mask)
+{
+    size_t pathlen;
+    ria_set_a (mask);
+    pathlen = strlen (path);
+    if (pathlen > 255) {
+        errno = EINVAL;
+        return -1;
+    }
+    while (pathlen) {
+        ria_push_char (path[--pathlen]);
+    }
+    ria_push_char (attr);
+    return ria_call_int (RIA_OP_CHMOD);
+}
diff --git a/libsrc/rp6502/f_closedir.c b/libsrc/rp6502/f_closedir.c
new file mode 100644
index 000000000..279483ca9
--- /dev/null
+++ b/libsrc/rp6502/f_closedir.c
@@ -0,0 +1,7 @@
+#include <rp6502.h>
+
+int __fastcall__ f_closedir (int dirdes)
+{
+    ria_set_ax (dirdes);
+    return ria_call_int (RIA_OP_CLOSEDIR);
+}
diff --git a/libsrc/rp6502/f_getcwd.c b/libsrc/rp6502/f_getcwd.c
new file mode 100644
index 000000000..3473b81e1
--- /dev/null
+++ b/libsrc/rp6502/f_getcwd.c
@@ -0,0 +1,18 @@
+#include <rp6502.h>
+#include <errno.h>
+#include <string.h>
+
+int __fastcall__ f_getcwd (char* name, int size)
+{
+    int i, ax;
+    ax = ria_call_int (RIA_OP_GETCWD);
+    if (ax > size) {
+        RIA.op = RIA_OP_ZXSTACK;
+        errno = ENOMEM;
+        return -1;
+    }
+    for (i = 0; i < ax; i++) {
+        name[i] = ria_pop_char ();
+    }
+    return ax;
+}
diff --git a/libsrc/rp6502/f_getfree.c b/libsrc/rp6502/f_getfree.c
new file mode 100644
index 000000000..13240591f
--- /dev/null
+++ b/libsrc/rp6502/f_getfree.c
@@ -0,0 +1,22 @@
+#include <rp6502.h>
+#include <errno.h>
+#include <string.h>
+
+int __fastcall__ f_getfree (const char* name, unsigned long* free, unsigned long* total)
+{
+    int ax;
+    size_t namelen = strlen (name);
+    if (namelen > 255) {
+        errno = EINVAL;
+        return -1;
+    }
+    while (namelen) {
+        ria_push_char (name[--namelen]);
+    }
+    ax = ria_call_int (RIA_OP_GETFREE);
+    if (ax >= 0) {
+        *free = ria_pop_long ();
+        *total = ria_pop_long ();
+    }
+    return ax;
+}
diff --git a/libsrc/rp6502/f_getlabel.c b/libsrc/rp6502/f_getlabel.c
new file mode 100644
index 000000000..89e72eac9
--- /dev/null
+++ b/libsrc/rp6502/f_getlabel.c
@@ -0,0 +1,21 @@
+#include <rp6502.h>
+#include <errno.h>
+#include <string.h>
+
+int __fastcall__ f_getlabel (const char* path, char* label)
+{
+    int i, ax;
+    size_t pathlen = strlen (path);
+    if (pathlen > 255) {
+        errno = EINVAL;
+        return -1;
+    }
+    while (pathlen) {
+        ria_push_char (path[--pathlen]);
+    }
+    ax = ria_call_int (RIA_OP_GETLABEL);
+    for (i = 0; i < ax; i++) {
+        label[i] = ria_pop_char ();
+    }
+    return ax;
+}
diff --git a/libsrc/rp6502/f_lseek.c b/libsrc/rp6502/f_lseek.c
new file mode 100644
index 000000000..ada9baab5
--- /dev/null
+++ b/libsrc/rp6502/f_lseek.c
@@ -0,0 +1,9 @@
+#include <rp6502.h>
+
+long __fastcall__ f_lseek (long offset, int whence, int fildes)
+{
+    ria_set_ax (fildes);
+    ria_push_long (offset);
+    ria_push_char (whence);
+    return ria_call_long (RIA_OP_LSEEK);
+}
diff --git a/libsrc/rp6502/f_mkdir.c b/libsrc/rp6502/f_mkdir.c
new file mode 100644
index 000000000..b27c21fd7
--- /dev/null
+++ b/libsrc/rp6502/f_mkdir.c
@@ -0,0 +1,16 @@
+#include <rp6502.h>
+#include <errno.h>
+#include <string.h>
+
+int __fastcall__ f_mkdir (const char* name)
+{
+    size_t namelen = strlen (name);
+    if (namelen > 255) {
+        errno = EINVAL;
+        return -1;
+    }
+    while (namelen) {
+        ria_push_char (name[--namelen]);
+    }
+    return ria_call_int (RIA_OP_MKDIR);
+}
diff --git a/libsrc/rp6502/f_opendir.c b/libsrc/rp6502/f_opendir.c
new file mode 100644
index 000000000..29faf776e
--- /dev/null
+++ b/libsrc/rp6502/f_opendir.c
@@ -0,0 +1,16 @@
+#include <rp6502.h>
+#include <errno.h>
+#include <string.h>
+
+int __fastcall__ f_opendir (const char* name)
+{
+    size_t namelen = strlen (name);
+    if (namelen > 255) {
+        errno = EINVAL;
+        return -1;
+    }
+    while (namelen) {
+        ria_push_char (name[--namelen]);
+    }
+    return ria_call_int (RIA_OP_OPENDIR);
+}
diff --git a/libsrc/rp6502/f_readdir.c b/libsrc/rp6502/f_readdir.c
new file mode 100644
index 000000000..45777c221
--- /dev/null
+++ b/libsrc/rp6502/f_readdir.c
@@ -0,0 +1,12 @@
+#include <rp6502.h>
+
+int __fastcall__ f_readdir (f_stat_t* dirent, int dirdes)
+{
+    int i, ax;
+    ria_set_ax (dirdes);
+    ax = ria_call_int (RIA_OP_READDIR);
+    for (i = 0; i < sizeof (f_stat_t); i++) {
+        ((char*)dirent)[i] = ria_pop_char ();
+    }
+    return ax;
+}
diff --git a/libsrc/rp6502/f_rewinddir.c b/libsrc/rp6502/f_rewinddir.c
new file mode 100644
index 000000000..bd2ebaa1b
--- /dev/null
+++ b/libsrc/rp6502/f_rewinddir.c
@@ -0,0 +1,7 @@
+#include <rp6502.h>
+
+int __fastcall__ f_rewinddir (int dirdes)
+{
+    ria_set_ax (dirdes);
+    return ria_call_int (RIA_OP_REWINDDIR);
+}
diff --git a/libsrc/rp6502/f_seekdir.c b/libsrc/rp6502/f_seekdir.c
new file mode 100644
index 000000000..5c6890e3d
--- /dev/null
+++ b/libsrc/rp6502/f_seekdir.c
@@ -0,0 +1,8 @@
+#include <rp6502.h>
+
+int __fastcall__ f_seekdir (long offs, int dirdes)
+{
+    ria_set_ax (dirdes);
+    ria_push_long (offs);
+    return ria_call_int (RIA_OP_SEEKDIR);
+}
diff --git a/libsrc/rp6502/f_setlabel.c b/libsrc/rp6502/f_setlabel.c
new file mode 100644
index 000000000..0cf77ea15
--- /dev/null
+++ b/libsrc/rp6502/f_setlabel.c
@@ -0,0 +1,16 @@
+#include <rp6502.h>
+#include <errno.h>
+#include <string.h>
+
+int __fastcall__ f_setlabel (const char* name)
+{
+    size_t namelen = strlen (name);
+    if (namelen > 255) {
+        errno = EINVAL;
+        return -1;
+    }
+    while (namelen) {
+        ria_push_char (name[--namelen]);
+    }
+    return ria_call_int (RIA_OP_SETLABEL);
+}
diff --git a/libsrc/rp6502/f_stat.c b/libsrc/rp6502/f_stat.c
new file mode 100644
index 000000000..3e3845639
--- /dev/null
+++ b/libsrc/rp6502/f_stat.c
@@ -0,0 +1,21 @@
+#include <rp6502.h>
+#include <errno.h>
+#include <string.h>
+
+int __fastcall__ f_stat (const char* path, f_stat_t* dirent)
+{
+    int i, ax;
+    size_t pathlen = strlen (path);
+    if (pathlen > 255) {
+        errno = EINVAL;
+        return -1;
+    }
+    while (pathlen) {
+        ria_push_char (path[--pathlen]);
+    }
+    ax = ria_call_int (RIA_OP_STAT);
+    for (i = 0; i < sizeof (f_stat_t); i++) {
+        ((char*)dirent)[i] = ria_pop_char ();
+    }
+    return ax;
+}
diff --git a/libsrc/rp6502/f_telldir.c b/libsrc/rp6502/f_telldir.c
new file mode 100644
index 000000000..1396e0a88
--- /dev/null
+++ b/libsrc/rp6502/f_telldir.c
@@ -0,0 +1,7 @@
+#include <rp6502.h>
+
+long __fastcall__ f_telldir (int dirdes)
+{
+    ria_set_ax (dirdes);
+    return ria_call_long (RIA_OP_TELLDIR);
+}
diff --git a/libsrc/rp6502/f_utime.c b/libsrc/rp6502/f_utime.c
new file mode 100644
index 000000000..a5c3e9753
--- /dev/null
+++ b/libsrc/rp6502/f_utime.c
@@ -0,0 +1,21 @@
+#include <rp6502.h>
+#include <errno.h>
+#include <string.h>
+
+int __fastcall__ f_utime (const char* path, unsigned fdate, unsigned ftime, unsigned crdate, unsigned crtime)
+{
+    size_t pathlen;
+    ria_set_ax (crtime);
+    pathlen = strlen (path);
+    if (pathlen > 255) {
+        errno = EINVAL;
+        return -1;
+    }
+    while (pathlen) {
+        ria_push_char (path[--pathlen]);
+    }
+    ria_push_int (fdate);
+    ria_push_int (ftime);
+    ria_push_int (crdate);
+    return ria_call_int (RIA_OP_UTIME);
+}
diff --git a/libsrc/rp6502/gettime.c b/libsrc/rp6502/gettime.c
index ee63c31ec..339ddeadb 100644
--- a/libsrc/rp6502/gettime.c
+++ b/libsrc/rp6502/gettime.c
@@ -5,8 +5,6 @@ extern int __clock_gettimespec (struct timespec* ts, unsigned char op);
 
 int clock_gettime (clockid_t clock_id, struct timespec* tp)
 {
-    (void)clock_id;
-    /* time.s doesn't set the stack value for clock_id (bug?) */
-    ria_set_ax (CLOCK_REALTIME);
+    ria_set_ax (clock_id);
     return __clock_gettimespec (tp, RIA_OP_CLOCK_GETTIME);
 }
diff --git a/libsrc/rp6502/gettimespec.c b/libsrc/rp6502/gettimespec.c
index 4dc3a0db3..5a07a46d8 100644
--- a/libsrc/rp6502/gettimespec.c
+++ b/libsrc/rp6502/gettimespec.c
@@ -4,7 +4,7 @@
 int __clock_gettimespec (struct timespec* ts, unsigned char op)
 /* Internal method shared by clock_getres and clock_gettime. */
 {
-    int ax = ria_call_int_errno (op);
+    int ax = ria_call_int (op);
     if (ax >= 0) {
         ts->tv_sec = ria_pop_long ();
         ts->tv_nsec = ria_pop_long ();
diff --git a/libsrc/rp6502/gettimezone.c b/libsrc/rp6502/gettimezone.c
index f3cb2a061..4c4584c07 100644
--- a/libsrc/rp6502/gettimezone.c
+++ b/libsrc/rp6502/gettimezone.c
@@ -1,11 +1,12 @@
 #include <rp6502.h>
 #include <time.h>
 
-int clock_gettimezone (clockid_t clock_id, struct _timezone* tz)
+int clock_gettimezone (time_t time, clockid_t clock_id, struct _timezone* tz)
 {
     int ax;
     ria_set_ax (clock_id);
-    ax = ria_call_int_errno (RIA_OP_CLOCK_GETTIMEZONE);
+    ria_push_long (time);
+    ax = ria_call_int (RIA_OP_CLOCK_GETTIMEZONE);
     if (ax >= 0) {
         char i;
         for (i = 0; i < sizeof (struct _timezone); i++) {
diff --git a/libsrc/rp6502/lseek.c b/libsrc/rp6502/lseek.c
index 29506612c..a40c7318d 100644
--- a/libsrc/rp6502/lseek.c
+++ b/libsrc/rp6502/lseek.c
@@ -3,9 +3,8 @@
 
 off_t __fastcall__ lseek (int fd, off_t offset, int whence)
 {
-    /* Modified argument order for short stacking offset */
     ria_push_long (offset);
     ria_push_char (whence);
     ria_set_ax (fd);
-    return ria_call_long_errno (RIA_OP_LSEEK);
+    return ria_call_long (RIA_OP_LSEEK);
 }
diff --git a/libsrc/rp6502/open.c b/libsrc/rp6502/open.c
index ab3a374a2..5750eb769 100644
--- a/libsrc/rp6502/open.c
+++ b/libsrc/rp6502/open.c
@@ -1,16 +1,18 @@
 #include <rp6502.h>
 #include <errno.h>
 #include <string.h>
+#include <fcntl.h>
 
 int __cdecl__ open (const char* name, int flags, ...)
 {
     size_t namelen = strlen (name);
     if (namelen > 255) {
-        return _mappederrno (EINVAL);
+        errno = EINVAL;
+        return -1;
     }
     while (namelen) {
         ria_push_char (name[--namelen]);
     }
     ria_set_ax (flags);
-    return ria_call_int_errno (RIA_OP_OPEN);
+    return ria_call_int (RIA_OP_OPEN);
 }
diff --git a/libsrc/rp6502/oserrlist.s b/libsrc/rp6502/oserrlist.s
deleted file mode 100644
index ef322e293..000000000
--- a/libsrc/rp6502/oserrlist.s
+++ /dev/null
@@ -1,86 +0,0 @@
-;
-; 2002-07-18, Ullrich von Bassewitz
-; 2022, ChaN
-; 2023, Rumbledethumps
-;
-; Defines the platform-specific error list.
-;
-; The table is built as a list of entries:
-;
-;       .byte   entrylen
-;       .byte   errorcode
-;       .asciiz errormsg
-;
-; and, terminated by an entry with length zero that is returned if the
-; error code could not be found.
-;
-
-.export __sys_oserrlist
-
-.include "rp6502.inc"
-.include "errno.inc"
-
-;----------------------------------------------------------------------------
-; Macros used to generate the list (may get moved to an include file?)
-
-; Regular entry
-.macro sys_oserr_entry code, msg
-    .local Start, End
-Start:
-    .byte End - Start
-    .byte code
-    .asciiz msg
-End:
-.endmacro
-
-; Sentinel entry
-.macro sys_oserr_sentinel msg
-    .byte 0  ; Length is always zero
-    .byte 0  ; Code is unused
-    .asciiz msg
-.endmacro
-
-;----------------------------------------------------------------------------
-; The error message table
-
-.rodata
-__sys_oserrlist:
-
-    sys_oserr_entry ENOENT                 , "No such file or directory"
-    sys_oserr_entry ENOMEM                 , "Out of memory"
-    sys_oserr_entry EACCES                 , "Permission denied"
-    sys_oserr_entry ENODEV                 , "No such device"
-    sys_oserr_entry EMFILE                 , "Too many open files"
-    sys_oserr_entry EBUSY                  , "Device or resource busy"
-    sys_oserr_entry EINVAL                 , "Invalid argument"
-    sys_oserr_entry ENOSPC                 , "No space left on device"
-    sys_oserr_entry EEXIST                 , "File exists"
-    sys_oserr_entry EAGAIN                 , "Try again"
-    sys_oserr_entry EIO                    , "I/O error"
-    sys_oserr_entry EINTR                  , "Interrupted system call"
-    sys_oserr_entry ENOSYS                 , "Function not implemented"
-    sys_oserr_entry ESPIPE                 , "Illegal seek"
-    sys_oserr_entry ERANGE                 , "Range error"
-    sys_oserr_entry EBADF                  , "Bad file number"
-    sys_oserr_entry ENOEXEC                , "Exec format error"
-    sys_oserr_entry EUNKNOWN               , "Unknown OS specific error"
-    sys_oserr_entry FR_DISK_ERR            , "A hard error occurred in the low level disk I/O layer"
-    sys_oserr_entry FR_INT_ERR             , "Assertion failed"
-    sys_oserr_entry FR_NOT_READY           , "The physical drive cannot work"
-    sys_oserr_entry FR_NO_FILE             , "Could not find the file"
-    sys_oserr_entry FR_NO_PATH             , "Could not find the path"
-    sys_oserr_entry FR_INVALID_NAME        , "The path name format is invalid"
-    sys_oserr_entry FR_DENIED              , "Access denied due to prohibited access or directory full"
-    sys_oserr_entry FR_EXIST               , "Access denied due to prohibited access"
-    sys_oserr_entry FR_INVALID_OBJECT      , "The file/directory object is invalid"
-    sys_oserr_entry FR_WRITE_PROTECTED     , "The physical drive is write protected"
-    sys_oserr_entry FR_INVALID_DRIVE       , "The logical drive number is invalid"
-    sys_oserr_entry FR_NOT_ENABLED         , "The volume has no work area"
-    sys_oserr_entry FR_NO_FILESYSTEM       , "There is no valid FAT volume"
-    sys_oserr_entry FR_MKFS_ABORTED        , "The f_mkfs() aborted due to any problem"
-    sys_oserr_entry FR_TIMEOUT             , "Could not get a grant to access the volume within defined period"
-    sys_oserr_entry FR_LOCKED              , "The operation is rejected according to the file sharing policy"
-    sys_oserr_entry FR_NOT_ENOUGH_CORE     , "LFN working buffer could not be allocated"
-    sys_oserr_entry FR_TOO_MANY_OPEN_FILES , "Number of open files > FF_FS_LOCK"
-    sys_oserr_entry FR_INVALID_PARAMETER   , "Given parameter is invalid"
-    sys_oserr_sentinel                       "Unknown error"
diff --git a/libsrc/rp6502/oserror.s b/libsrc/rp6502/oserror.s
deleted file mode 100644
index 706bcfa65..000000000
--- a/libsrc/rp6502/oserror.s
+++ /dev/null
@@ -1,66 +0,0 @@
-;
-; 2000-05-17, Ullrich von Bassewitz
-; 2022, ChaN
-; 2023, Rumbledethumps
-;
-; int __fastcall__ __osmaperrno (unsigned char oserror);
-;
-; RP6502 will respond with a union of CC65 and FatFs errnos.
-; This will map FatFs errors into the CC65 range for portable code.
-
-EFATFS_START := 32
-
-.include "rp6502.inc"
-.include "errno.inc"
-
-.code
-
-___osmaperrno:
-    cmp #EFATFS_START
-    bmi @L2
-
-    ldx #ErrTabSize
-@L1:
-    cmp ErrTab-2,x      ; Search for the error code
-    beq @L3             ; Jump if found
-    dex
-    dex
-    bne @L1             ; Next entry
-
-; Code not found, return EUNKNOWN
-    lda #<EUNKNOWN
-    ldx #>EUNKNOWN
-@L2:
-    rts
-
-; Found the code
-@L3:
-    lda ErrTab-1,x
-    ldx #$00            ; High byte always zero
-    rts
-
-.rodata
-
-ErrTab:
-
-    .byte FR_DISK_ERR            , EIO       ; A hard error occurred in the low level disk I/O layer
-;   .byte FR_INT_ERR             , EUNKNOWN  ; Assertion failed
-    .byte FR_NOT_READY           , EBUSY     ; The physical drive cannot work
-    .byte FR_NO_FILE             , ENOENT    ; Could not find the file
-    .byte FR_NO_PATH             , ENOENT    ; Could not find the path
-    .byte FR_INVALID_NAME        , EINVAL    ; The path name format is invalid
-    .byte FR_DENIED              , EACCES    ; Access denied due to prohibited access or directory full
-    .byte FR_EXIST               , EEXIST    ; Access denied due to prohibited access
-    .byte FR_INVALID_OBJECT      , EINVAL    ; The file/directory object is invalid
-    .byte FR_WRITE_PROTECTED     , EACCES    ; The physical drive is write protected
-    .byte FR_INVALID_DRIVE       , ENODEV    ; The logical drive number is invalid
-;   .byte FR_NOT_ENABLED         , EUNKNOWN  ; The volume has no work area
-;   .byte FR_NO_FILESYSTEM       , EUNKNOWN  ; There is no valid FAT volume
-;   .byte FR_MKFS_ABORTED        , EUNKNOWN  ; The f_mkfs() aborted due to any problem
-;   .byte FR_TIMEOUT             , EUNKNOWN  ; Could not get a grant to access the volume within defined period
-    .byte FR_LOCKED              , EBUSY     ; The operation is rejected according to the file sharing policy
-    .byte FR_NOT_ENOUGH_CORE     , ENOMEM    ; LFN working buffer could not be allocated
-    .byte FR_TOO_MANY_OPEN_FILES , EMFILE    ; Number of open files > FF_FS_LOCK
-    .byte FR_INVALID_PARAMETER   , EINVAL    ; Given parameter is invalid
-
-ErrTabSize = (* - ErrTab)
diff --git a/libsrc/rp6502/read_xram.c b/libsrc/rp6502/read_xram.c
index f88a036ee..e14ac29d4 100644
--- a/libsrc/rp6502/read_xram.c
+++ b/libsrc/rp6502/read_xram.c
@@ -5,5 +5,5 @@ int __fastcall__ read_xram (unsigned buf, unsigned count, int fildes)
     ria_push_int (buf);
     ria_push_int (count);
     ria_set_ax (fildes);
-    return ria_call_int_errno (RIA_OP_READ_XRAM);
+    return ria_call_int (RIA_OP_READ_XRAM);
 }
diff --git a/libsrc/rp6502/read_xstack.c b/libsrc/rp6502/read_xstack.c
index 70eebad2f..952323f32 100644
--- a/libsrc/rp6502/read_xstack.c
+++ b/libsrc/rp6502/read_xstack.c
@@ -5,7 +5,7 @@ int __fastcall__ read_xstack (void* buf, unsigned count, int fildes)
     int i, ax;
     ria_push_int (count);
     ria_set_ax (fildes);
-    ax = ria_call_int_errno (RIA_OP_READ_XSTACK);
+    ax = ria_call_int (RIA_OP_READ_XSTACK);
     for (i = 0; i < ax; i++) {
         ((char*)buf)[i] = ria_pop_char ();
     }
diff --git a/libsrc/rp6502/remove.s b/libsrc/rp6502/remove.s
new file mode 100644
index 000000000..3bd91001d
--- /dev/null
+++ b/libsrc/rp6502/remove.s
@@ -0,0 +1,14 @@
+;
+; Ullrich von Bassewitz, 2003-08-12
+;
+; int __fastcall__ remove (const char* name);
+;
+
+        .export         _remove
+
+        .import         __sysremove
+
+
+;--------------------------------------------------------------------------
+
+_remove = __sysremove
diff --git a/libsrc/rp6502/rename.s b/libsrc/rp6502/rename.s
new file mode 100644
index 000000000..0b85a6134
--- /dev/null
+++ b/libsrc/rp6502/rename.s
@@ -0,0 +1,14 @@
+;
+; Ullrich von Bassewitz, 2003-08-12
+;
+; int __fastcall__ rename (const char* oldname, const char* newname);
+;
+
+        .export         _rename
+
+        .import         __sysrename
+
+
+;--------------------------------------------------------------------------
+
+_rename = __sysrename
diff --git a/libsrc/rp6502/ria.s b/libsrc/rp6502/ria.s
index 78da4daba..5fb858a03 100644
--- a/libsrc/rp6502/ria.s
+++ b/libsrc/rp6502/ria.s
@@ -9,10 +9,8 @@
 .export _ria_pop_long, _ria_pop_int
 .export _ria_set_axsreg, _ria_set_ax
 .export _ria_call_int, _ria_call_long
-.export _ria_call_int_errno, _ria_call_long_errno
 
-.importzp c_sp, sreg
-.import ___mappederrno, incsp1
+.importzp sreg
 
 .code
 
@@ -69,21 +67,3 @@ _ria_call_long:
     ldy RIA_SREG+1
     sty sreg+1
     rts
-
-; int __fastcall__ ria_call_int_errno(unsigned char op);
-_ria_call_int_errno:
-    sta RIA_OP
-    jsr RIA_SPIN
-    ldx RIA_X
-    bmi ERROR
-    rts
-
-; long __fastcall__ ria_call_long_errno(unsigned char op);
-_ria_call_long_errno:
-    jsr _ria_call_long
-    bmi ERROR
-    rts
-
-ERROR:
-    lda RIA_ERRNO
-    jmp ___mappederrno
diff --git a/libsrc/rp6502/ria_tzset.c b/libsrc/rp6502/ria_tzset.c
new file mode 100644
index 000000000..3f39e44f2
--- /dev/null
+++ b/libsrc/rp6502/ria_tzset.c
@@ -0,0 +1,9 @@
+#include <rp6502.h>
+#include <time.h>
+
+int clock_gettimezone (time_t time, clockid_t clock_id, struct _timezone* tz);
+
+void ria_tzset (unsigned long time)
+{
+    clock_gettimezone (time, CLOCK_REALTIME, &_tz);
+}
diff --git a/libsrc/rp6502/settime.c b/libsrc/rp6502/settime.c
index 1ba1d2e3e..4b7f8c73e 100644
--- a/libsrc/rp6502/settime.c
+++ b/libsrc/rp6502/settime.c
@@ -6,5 +6,5 @@ int clock_settime (clockid_t clock_id, const struct timespec* tp)
     ria_set_ax (clock_id);
     ria_push_long (tp->tv_nsec);
     ria_push_long (tp->tv_sec);
-    return ria_call_int_errno (RIA_OP_CLOCK_SETTIME);
+    return ria_call_int (RIA_OP_CLOCK_SETTIME);
 }
diff --git a/libsrc/rp6502/stdin_opt.c b/libsrc/rp6502/stdin_opt.c
index 3a9ccfde4..ddc1869a1 100644
--- a/libsrc/rp6502/stdin_opt.c
+++ b/libsrc/rp6502/stdin_opt.c
@@ -1,9 +1,8 @@
-
 #include <rp6502.h>
 
 int __fastcall__ stdin_opt (unsigned long ctrl_bits, unsigned char str_length)
 {
     ria_push_long (ctrl_bits);
     ria_set_a (str_length);
-    return ria_call_int_errno (RIA_OP_STDIN_OPT);
+    return ria_call_int (RIA_OP_STDIN_OPT);
 }
diff --git a/libsrc/rp6502/syncfs.c b/libsrc/rp6502/syncfs.c
new file mode 100644
index 000000000..34c12a8f6
--- /dev/null
+++ b/libsrc/rp6502/syncfs.c
@@ -0,0 +1,8 @@
+#include <rp6502.h>
+#include <unistd.h>
+
+int __fastcall__ syncfs (int fd)
+{
+    ria_set_ax (fd);
+    return ria_call_int (RIA_OP_SYNCFS);
+}
diff --git a/libsrc/rp6502/syschdir.c b/libsrc/rp6502/syschdir.c
new file mode 100644
index 000000000..98ad91e47
--- /dev/null
+++ b/libsrc/rp6502/syschdir.c
@@ -0,0 +1,16 @@
+#include <rp6502.h>
+#include <errno.h>
+#include <string.h>
+
+int __fastcall__ _syschdir (const char* name)
+{
+    size_t namelen = strlen (name);
+    if (namelen > 255) {
+        errno = EINVAL;
+        return -1;
+    }
+    while (namelen) {
+        ria_push_char (name[--namelen]);
+    }
+    return ria_call_int (RIA_OP_CHDIR);
+}
diff --git a/libsrc/rp6502/sysremove.c b/libsrc/rp6502/sysremove.c
index d8c1ced98..32010d5bf 100644
--- a/libsrc/rp6502/sysremove.c
+++ b/libsrc/rp6502/sysremove.c
@@ -2,15 +2,16 @@
 #include <errno.h>
 #include <string.h>
 
-unsigned char __fastcall__ _sysremove (const char* name)
+int __fastcall__ _sysremove (const char* name)
 {
     size_t namelen;
     namelen = strlen (name);
     if (namelen > 255) {
-        return _mappederrno (EINVAL);
+        RIA.errno_ = EINVAL;
+        return -1;
     }
     while (namelen) {
         ria_push_char (name[--namelen]);
     }
-    return ria_call_int_errno (RIA_OP_UNLINK);
+    return ria_call_int (RIA_OP_UNLINK);
 }
diff --git a/libsrc/rp6502/sysrename.c b/libsrc/rp6502/sysrename.c
index 46bdd8b31..09f971918 100644
--- a/libsrc/rp6502/sysrename.c
+++ b/libsrc/rp6502/sysrename.c
@@ -2,13 +2,14 @@
 #include <errno.h>
 #include <string.h>
 
-unsigned char __fastcall__ _sysrename (const char* oldpath, const char* newpath)
+int __fastcall__ _sysrename (const char* oldpath, const char* newpath)
 {
     size_t oldpathlen, newpathlen;
     oldpathlen = strlen (oldpath);
     newpathlen = strlen (newpath);
     if (oldpathlen + newpathlen > 510) {
-        return _mappederrno (EINVAL);
+        errno = EINVAL;
+        return -1;
     }
     while (oldpathlen) {
         ria_push_char (oldpath[--oldpathlen]);
@@ -17,5 +18,5 @@ unsigned char __fastcall__ _sysrename (const char* oldpath, const char* newpath)
     while (newpathlen) {
         ria_push_char (newpath[--newpathlen]);
     }
-    return ria_call_int_errno (RIA_OP_RENAME);
+    return ria_call_int (RIA_OP_RENAME);
 }
diff --git a/libsrc/rp6502/write_xram.c b/libsrc/rp6502/write_xram.c
index 31a553813..0a46ec62c 100644
--- a/libsrc/rp6502/write_xram.c
+++ b/libsrc/rp6502/write_xram.c
@@ -2,8 +2,8 @@
 
 int __fastcall__ write_xram (unsigned buf, unsigned count, int fildes)
 {
+    ria_set_ax (fildes);
     ria_push_int (buf);
     ria_push_int (count);
-    ria_set_ax (fildes);
-    return ria_call_int_errno (RIA_OP_WRITE_XRAM);
+    return ria_call_int (RIA_OP_WRITE_XRAM);
 }
diff --git a/libsrc/rp6502/write_xstack.c b/libsrc/rp6502/write_xstack.c
index 29285a87e..98c90c757 100644
--- a/libsrc/rp6502/write_xstack.c
+++ b/libsrc/rp6502/write_xstack.c
@@ -5,11 +5,12 @@ int __fastcall__ write_xstack (const void* buf, unsigned count, int fildes)
 {
     unsigned i;
     if (count > 512) {
-        return _mappederrno (EINVAL);
+        errno = EINVAL;
+        return -1;
     }
     for (i = count; i;) {
         ria_push_char (((char*)buf)[--i]);
     }
     ria_set_ax (fildes);
-    return ria_call_int_errno (RIA_OP_WRITE_XSTACK);
+    return ria_call_int (RIA_OP_WRITE_XSTACK);
 }
diff --git a/libsrc/rp6502/xreg.s b/libsrc/rp6502/xreg.s
index a882ab10f..140d60855 100644
--- a/libsrc/rp6502/xreg.s
+++ b/libsrc/rp6502/xreg.s
@@ -6,7 +6,7 @@
 
 .export _xreg
 .importzp c_sp
-.import addysp, _ria_call_int_errno
+.import addysp, _ria_call_int
 
 .include "rp6502.inc"
 
@@ -32,6 +32,6 @@
 
     ; run RIA operation
     lda #RIA_OP_XREG
-    jmp _ria_call_int_errno
+    jmp _ria_call_int
 
 .endproc
diff --git a/libsrc/rp6502/xregn.c b/libsrc/rp6502/xregn.c
index ec040be20..eaa6aa7b7 100644
--- a/libsrc/rp6502/xregn.c
+++ b/libsrc/rp6502/xregn.c
@@ -15,5 +15,5 @@ int __cdecl__ xregn (char device, char channel, unsigned char address, unsigned
         RIA.xstack = v;
     }
     va_end (args);
-    return ria_call_int_errno (RIA_OP_XREG);
+    return ria_call_int (RIA_OP_XREG);
 }