diff --git a/CMakeLists.txt b/CMakeLists.txt
index 29f9348..9476bf4 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -4,6 +4,9 @@ project(gw-basic-2026 C)
 set(CMAKE_C_STANDARD 11)
 set(CMAKE_C_STANDARD_REQUIRED ON)
 
+# POSIX extensions (opendir, chdir, strcasecmp, etc.)
+add_compile_definitions(_DEFAULT_SOURCE)
+
 # Warnings
 add_compile_options(-Wall -Wextra -Wno-unused-parameter)
 
diff --git a/README.md b/README.md
index 9aab982..bd99f32 100644
--- a/README.md
+++ b/README.md
@@ -23,7 +23,7 @@ Interactive mode launches the authentic GW-BASIC full-screen editor:
 
 ```
 $ ./gwbasic
-GW-BASIC 2026 0.5.0
+GW-BASIC 2026 0.6.0
 (C) Eremey Valetov 2026. MIT License.
 Based on Microsoft GW-BASIC assembly source.
 Ok
@@ -73,7 +73,8 @@ SPACE$, STRING$, HEX$, OCT$, INSTR, INPUT$
 | Program I/O | SAVE, LOAD, MERGE, CHAIN |
 | Error handling | ON ERROR GOTO, RESUME, ERROR, ERR, ERL |
 | User functions | DEF FN, RANDOMIZE |
-| File management | KILL, NAME |
+| File management | KILL, NAME, FILES, MKDIR, RMDIR, CHDIR, SHELL |
+| Date/time | DATE$, TIME$, TIMER |
 | Screen | LOCATE, COLOR, WIDTH, SCREEN, KEY ON/OFF/LIST |
 | Graphics | PSET, PRESET, LINE, CIRCLE, DRAW, PAINT |
 | Sound | SOUND, BEEP, PLAY (MML) |
@@ -145,7 +146,7 @@ Key design differences from the original:
 
 ## Tests
 
-50 test programs in `tests/programs/`, with CI via GitHub Actions:
+52 test programs in `tests/programs/`, with CI via GitHub Actions:
 
 ```bash
 bash tests/run_tests.sh
diff --git a/include/error.h b/include/error.h
index 1d10c89..8125f2f 100644
--- a/include/error.h
+++ b/include/error.h
@@ -49,6 +49,8 @@
 #define ERR_NM  65   /* Bad file name */
 #define ERR_DS  67   /* Direct statement in file */
 #define ERR_TF  68   /* Too many files */
+#define ERR_DA  70   /* Disk already exists */
+#define ERR_PE  76   /* Path not found */
 
 const char *gw_error_msg(int errnum);
 void gw_error(int errnum);
diff --git a/include/gwbasic.h b/include/gwbasic.h
index 0ff53c6..aa4ed47 100644
--- a/include/gwbasic.h
+++ b/include/gwbasic.h
@@ -10,7 +10,7 @@
 #include "gw_math.h"
 #include "strings.h"
 
-#define GW_VERSION "0.5.0"
+#define GW_VERSION "0.6.0"
 #define GW_BANNER "GW-BASIC " GW_VERSION
 
 /* Tokenizer */
diff --git a/src/error.c b/src/error.c
index d4e6c1c..6280f79 100644
--- a/src/error.c
+++ b/src/error.c
@@ -52,6 +52,8 @@ static const struct { int num; const char *msg; } error_table[] = {
     { 65, "Bad file name" },
     { 67, "Direct statement in file" },
     { 68, "Too many files" },
+    { 70, "Disk already exists" },
+    { 76, "Path not found" },
     {  0, NULL }
 };
 
diff --git a/src/eval.c b/src/eval.c
index 86962bd..8f83420 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -4,6 +4,7 @@
 #include <string.h>
 #include <stdlib.h>
 #include <math.h>
+#include <time.h>
 
 /*
  * Expression evaluator - reimplements GWEVAL.ASM's FRMEVL.
@@ -919,7 +920,7 @@ static gw_value_t eval_atom(void)
         gw.text_ptr = save;
     }
 
-    /* Extended statement tokens that work as functions (DATE$, TIME$) */
+    /* Extended statement tokens that work as functions (DATE$, TIME$, TIMER) */
     if (tok == TOK_PREFIX_FE) {
         uint8_t *save = gw.text_ptr;
         gw_chrget();
@@ -928,13 +929,29 @@ static gw_value_t eval_atom(void)
             gw_chrget();
             gw_value_t v;
             v.type = VT_STR;
+            char tbuf[16];
+            time_t now = time(NULL);
+            struct tm *tm = localtime(&now);
             if (xtok == XSTMT_DATE) {
-                v.sval = gw_str_from_cstr("01-01-2026");
+                snprintf(tbuf, sizeof(tbuf), "%02d-%02d-%04d",
+                         tm->tm_mon + 1, tm->tm_mday, tm->tm_year + 1900);
+                v.sval = gw_str_from_cstr(tbuf);
             } else {
-                v.sval = gw_str_from_cstr("00:00:00");
+                snprintf(tbuf, sizeof(tbuf), "%02d:%02d:%02d",
+                         tm->tm_hour, tm->tm_min, tm->tm_sec);
+                v.sval = gw_str_from_cstr(tbuf);
             }
             return v;
         }
+        if (xtok == XSTMT_TIMER) {
+            gw_chrget();
+            time_t now = time(NULL);
+            struct tm *tm = localtime(&now);
+            gw_value_t v;
+            v.type = VT_SNG;
+            v.fval = (float)(tm->tm_hour * 3600 + tm->tm_min * 60 + tm->tm_sec);
+            return v;
+        }
         gw.text_ptr = save;
     }
 
diff --git a/src/interp.c b/src/interp.c
index 04a5145..78d9599 100644
--- a/src/interp.c
+++ b/src/interp.c
@@ -7,6 +7,10 @@
 #include <stdlib.h>
 #include <stdio.h>
 #include <math.h>
+#include <dirent.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <errno.h>
 
 /*
  * Execution loop and control flow - the heart of the interpreter.
@@ -15,6 +19,14 @@
 
 jmp_buf gw_run_jmp;
 
+static int ci_strcmp(const char *a, const char *b)
+{
+    for (;; a++, b++) {
+        int d = tolower((unsigned char)*a) - tolower((unsigned char)*b);
+        if (d != 0 || !*a) return d;
+    }
+}
+
 /* ================================================================
  * Program Storage
  * ================================================================ */
@@ -873,6 +885,124 @@ void gw_exec_stmt(void)
             free(cmd);
             return;
         }
+        /* FILES [filespec$] */
+        if (xstmt == XSTMT_FILES) {
+            gw_chrget();
+            gw_skip_spaces();
+            char *pattern = NULL;
+            if (gw_chrgot() && gw_chrgot() != ':' && gw_chrgot() != TOK_ELSE) {
+                gw_value_t v = gw_eval_str();
+                pattern = gw_str_to_cstr(&v.sval);
+                gw_str_free(&v.sval);
+            }
+            const char *dir = ".";
+            char dirpath[256] = ".";
+            const char *wild = NULL;
+            if (pattern) {
+                /* Split "dir/pattern" into directory and wildcard */
+                char *sep = strrchr(pattern, '/');
+                if (sep) {
+                    *sep = '\0';
+                    snprintf(dirpath, sizeof(dirpath), "%s", pattern);
+                    dir = dirpath;
+                    wild = sep + 1;
+                } else {
+                    wild = pattern;
+                }
+                if (wild && !*wild) wild = NULL;
+            }
+            DIR *dp = opendir(dir);
+            if (!dp) { free(pattern); gw_error(ERR_PE); }
+            struct dirent *ent;
+            int col = 0;
+            while ((ent = readdir(dp)) != NULL) {
+                if (ent->d_name[0] == '.') continue;
+                if (wild) {
+                    /* Simple *.ext matching: if wild starts with *. check extension */
+                    if (wild[0] == '*' && wild[1] == '.') {
+                        const char *ext = strrchr(ent->d_name, '.');
+                        if (!ext || ci_strcmp(ext + 1, wild + 2) != 0) continue;
+                    } else if (strcmp(wild, "*.*") != 0 && strcmp(wild, "*") != 0) {
+                        /* Exact match */
+                        if (ci_strcmp(ent->d_name, wild) != 0) continue;
+                    }
+                }
+                char entry[270];
+                snprintf(entry, sizeof(entry), "%-14s", ent->d_name);
+                if (gw_hal) gw_hal->puts(entry);
+                else fputs(entry, stdout);
+                col += 14;
+                if (col >= 70) {
+                    if (gw_hal) gw_hal->puts("\n");
+                    else fputs("\n", stdout);
+                    col = 0;
+                }
+            }
+            if (col > 0) {
+                if (gw_hal) gw_hal->puts("\n");
+                else fputs("\n", stdout);
+            }
+            closedir(dp);
+            free(pattern);
+            return;
+        }
+        /* SHELL [command$] */
+        if (xstmt == XSTMT_SHELL) {
+            gw_chrget();
+            gw_skip_spaces();
+            if (gw_chrgot() && gw_chrgot() != ':' && gw_chrgot() != TOK_ELSE) {
+                gw_value_t v = gw_eval_str();
+                char *cmd = gw_str_to_cstr(&v.sval);
+                gw_str_free(&v.sval);
+                int rc = system(cmd);
+                free(cmd);
+                (void)rc;
+            } else {
+                const char *sh = getenv("SHELL");
+                if (!sh) sh = "/bin/sh";
+                int rc = system(sh);
+                (void)rc;
+            }
+            return;
+        }
+        /* CHDIR path$ */
+        if (xstmt == XSTMT_CHDIR) {
+            gw_chrget();
+            gw_value_t v = gw_eval_str();
+            char *path = gw_str_to_cstr(&v.sval);
+            gw_str_free(&v.sval);
+            if (chdir(path) != 0) { free(path); gw_error(ERR_PE); }
+            free(path);
+            return;
+        }
+        /* MKDIR path$ */
+        if (xstmt == XSTMT_MKDIR) {
+            gw_chrget();
+            gw_value_t v = gw_eval_str();
+            char *path = gw_str_to_cstr(&v.sval);
+            gw_str_free(&v.sval);
+            if (mkdir(path, 0755) != 0) {
+                int e = errno;
+                free(path);
+                gw_error(e == EEXIST ? ERR_FE : ERR_PE);
+            }
+            free(path);
+            return;
+        }
+        /* RMDIR path$ */
+        if (xstmt == XSTMT_RMDIR) {
+            gw_chrget();
+            gw_value_t v = gw_eval_str();
+            char *path = gw_str_to_cstr(&v.sval);
+            gw_str_free(&v.sval);
+            if (rmdir(path) != 0) {
+                int e = errno;
+                free(path);
+                gw_error(e == ENOENT ? ERR_PE : ERR_FF);
+            }
+            free(path);
+            return;
+        }
         /* Stubs: VIEW, WINDOW, PALETTE */
         if (xstmt == XSTMT_VIEW ||
             xstmt == XSTMT_WINDOW || xstmt == XSTMT_PALETTE) {
diff --git a/tests/programs/datetime.bas b/tests/programs/datetime.bas
new file mode 100644
index 0000000..dfc79c7
--- /dev/null
+++ b/tests/programs/datetime.bas
@@ -0,0 +1,15 @@
+10 REM DATE$, TIME$, TIMER test
+20 D$ = DATE$
+30 T$ = TIME$
+40 R = TIMER
+50 IF LEN(D$) <> 10 THEN PRINT "FAIL date len": END
+60 IF MID$(D$,3,1) <> "-" THEN PRINT "FAIL date sep1": END
+70 IF MID$(D$,6,1) <> "-" THEN PRINT "FAIL date sep2": END
+80 IF LEN(T$) <> 8 THEN PRINT "FAIL time len": END
+90 IF MID$(T$,3,1) <> ":" THEN PRINT "FAIL time sep1": END
+100 IF MID$(T$,6,1) <> ":" THEN PRINT "FAIL time sep2": END
+110 IF R < 0 OR R > 86400 THEN PRINT "FAIL timer range": END
+120 PRINT "DATE$ = "; D$
+130 PRINT "TIME$ = "; T$
+140 PRINT "TIMER ="; INT(R)
+150 PRINT "All date/time tests passed"
diff --git a/tests/programs/filesystem.bas b/tests/programs/filesystem.bas
new file mode 100644
index 0000000..36b65e6
--- /dev/null
+++ b/tests/programs/filesystem.bas
@@ -0,0 +1,11 @@
+10 REM FILES, MKDIR, CHDIR, RMDIR test
+20 MKDIR "gwb_test_dir"
+30 OPEN "gwb_test_dir/test.txt" FOR OUTPUT AS #1
+40 PRINT #1, "hello"
+50 CLOSE #1
+60 CHDIR "gwb_test_dir"
+70 SHELL "pwd > /dev/null"
+80 CHDIR ".."
+90 KILL "gwb_test_dir/test.txt"
+100 RMDIR "gwb_test_dir"
+110 PRINT "All filesystem tests passed"