diff --git a/ka/command.k b/ka/command.k
index 7402476..f67c10c 100644
--- a/ka/command.k
+++ b/ka/command.k
@@ -22,3 +22,5 @@ start:
 include "usr/cmd/main.k"
 include "usr/cmd/dir.k"
 
+cmd.versionstr = "COMMAND.COM, version 0.1 (KVISC)\nCopyright (C) 2019, The OS/K Team\nMIT license (permissive), see LICENCE file in source tree"
+
diff --git a/ka/crt/sys.k b/ka/crt/sys.k
index 53e6db8..e331de4 100644
--- a/ka/crt/sys.k
+++ b/ka/crt/sys.k
@@ -24,6 +24,13 @@ Sys.FindNext := 0x21
 ;
 Sys.Exit := 0x00
 
+;
+; SHUTDOWN syscall
+;
+; End virtual machine
+;
+Sys.Shutdown := 0x01
+
 ; Halt mode
 Sys.HLT := 0x99
 
diff --git a/ka/sys/intr/trap0.k b/ka/sys/intr/trap0.k
index bab4589..11c9cf8 100644
--- a/ka/sys/intr/trap0.k
+++ b/ka/sys/intr/trap0.k
@@ -16,6 +16,7 @@ trap0_handler:
 
     b.z rax, Sys.HLT, .handle_HLT
     b.z rax, Sys.Exit, .handle_Exit
+    b.z rax, Sys.Shutdown, .handle_Shutdown
     b.z rax, Sys.FindNext, .handle_FindNext
     b.z rax, Sys.FindFirst, .handle_FindFirst
 
@@ -107,6 +108,9 @@ trap0_handler:
 ;
 ; Misc.
 ;
+.handle_Shutdown:
+    stop
+
 .handle_HLT:
     hlt
 .HLT.loop:
diff --git a/ka/usr/cmd/main.k b/ka/usr/cmd/main.k
index 965b39f..111ebff 100644
--- a/ka/usr/cmd/main.k
+++ b/ka/usr/cmd/main.k
@@ -68,7 +68,6 @@ main:
     jmp .input_loop
 
 .extract_argv0:
-
     ; did we read anything at all?
     ; if not, just go back to waiting input
     b.z rcx, 0, .print_prompt
@@ -79,8 +78,24 @@ main:
     scasb.rep.nz rdx, ' '
 
     ; argv1 exists? if so, save its position
-    ; (to do)
+    mov r11, rdx
+    b.z b[r11], 0, .no_argv1
+    inc r11
 
+.next_space:
+    mov rx8, b[r11]
+    b.z rx8, 0, .no_argv1
+
+    ; skip spaces
+    cmp rx8, ' '
+    inc.z r11
+    jmp.z .next_space
+
+    mov q[argv1pos], r11
+
+    ; fallthrough
+
+.no_argv1:
     ; empty argv0
     mov rcx, argbuf.size
     mov rax, argv0
@@ -94,13 +109,48 @@ main:
 
 .detect_builtin:
 
-.builtin_dir = "dir"
+.builtin_cls = "cls"
+    mov ax0, argv0
+    mov ax1, .builtin_cls
+    call strcmp
+    b.z rax, 0, .handle_CLS
 
+.builtin_dir = "dir"
     mov ax0, argv0
     mov ax1, .builtin_dir
     call strcmp
     b.z rax, 0, .handle_DIR
 
+.builtin_echo = "echo"
+    mov ax0, argv0
+    mov ax1, .builtin_echo
+    call strcmp
+    b.z rax, 0, .handle_ECHO
+
+.builtin_exit = "exit"
+    mov ax0, argv0
+    mov ax1, .builtin_exit
+    call strcmp
+    b.z rax, 0, .handle_EXIT
+
+.builtin_help = "help"
+    mov ax0, argv0
+    mov ax1, .builtin_help
+    call strcmp
+    b.z rax, 0, .handle_HELP
+
+.builtin_print = "print"
+    mov ax0, argv0
+    mov ax1, .builtin_print
+    call strcmp
+    b.z rax, 0, .handle_PRINT
+
+.builtin_ver = "ver"
+    mov ax0, argv0
+    mov ax1, .builtin_ver
+    call strcmp
+    b.z rax, 0, .handle_VER
+
     ; fallthrough
 
 .exec_prog:
@@ -122,7 +172,68 @@ main:
 ;
 ; call builtins
 ;
+.handle_CLS:
+    prn 0xC15000AF
+    jmp .print_prompt
+
 .handle_DIR:
     call builtins.dir
     jmp .print_prompt
 
+.handle_ECHO:
+    mov rdx, q[argv1pos]
+    b.z rdx, 0, .echo.end
+
+    mov rcx, argbuf.size
+    prns.rep.nz rdx
+
+.echo.end:
+    prn 10
+    jmp .print_prompt
+
+.handle_EXIT:
+    mov rax, Sys.Shutdown
+    trap 0
+
+.handle_PRINT:
+    jmp .print_prompt
+
+.handle_VER:
+    mov rcx, STRLEN_MAX
+    mov rdx, cmd.versionstr
+    prns.rep.nz rdx
+    prn 10
+
+    jmp .print_prompt
+
+.handle_HELP:
+    mov rcx, STRLEN_MAX
+
+    mov rdx, .helpmsg
+    prns.rep.nz rdx
+    mov rdx, .helpmsg.cls
+    prns.rep.nz rdx
+    mov rdx, .helpmsg.dir
+    prns.rep.nz rdx
+    mov rdx, .helpmsg.echo
+    prns.rep.nz rdx
+    mov rdx, .helpmsg.exit
+    prns.rep.nz rdx
+    mov rdx, .helpmsg.help
+    prns.rep.nz rdx
+    mov rdx, .helpmsg.print
+    prns.rep.nz rdx
+    mov rdx, .helpmsg.ver
+    prns.rep.nz rdx
+
+    jmp .print_prompt
+
+.helpmsg       = "The following commands are built-in:\n"
+.helpmsg.cls   = "    CLS        Clear screen\n"
+.helpmsg.dir   = "    DIR        Print contents of current directory\n"
+.helpmsg.echo  = "    ECHO       Write arguments to standard output\n"
+.helpmsg.exit  = "    EXIT       Initiate machine shutdown\n"
+.helpmsg.help  = "    HELP       Show these messages\n"
+.helpmsg.print = "    PRINT      Show contents of text file\n"
+.helpmsg.ver   = "    VER        Show current COMMAND.COM and DOS kernel versions\n"
+
diff --git a/vm/in/debug.c b/vm/in/debug.c
index 8b02163..994394b 100644
--- a/vm/in/debug.c
+++ b/vm/in/debug.c
@@ -26,7 +26,7 @@ IMPL_START_1(dump)
 {
     (void)v1;
 
-#if 1
+#ifndef NDEBUG
     if (ctx->dumpsw && !v1)
         trace("0x%lX:\t...\n", rpc);
 
diff --git a/vm/in/inout.c b/vm/in/inout.c
index 2d891b7..34bf153 100644
--- a/vm/in/inout.c
+++ b/vm/in/inout.c
@@ -6,10 +6,17 @@
 
 IMPL_START_1(prn)
 {
-    if (p1->mlen > 1) {
-        trace("prn warning: large access size\n");
+    // Magic value? :)
+    if (__builtin_expect(v1 == 0xC15000AF, 0))
+        console_clear(ctx);
+
+    else
+    {
+        if (p1->mlen > 1) {
+            trace("prn warning: large access size\n");
+        }
+        console_putc(ctx, (char)v1);
     }
-    console_putc(ctx, (char)v1);
 }
 IMPL_END
 
diff --git a/vm/pc/console.c b/vm/pc/console.c
index 6deba8b..7b99c8b 100644
--- a/vm/pc/console.c
+++ b/vm/pc/console.c
@@ -26,6 +26,9 @@ char scr_lines[CONSOLE_HEIGHT][CONSOLE_WIDTH+1] = { 0 };
 SDL_Texture *scr_texts[CONSOLE_HEIGHT] = { 0 };
 SDL_Rect *scr_rects[CONSOLE_HEIGHT] = { 0 };
 
+int csn_x = 0;
+int csn_y = 0;
+
 //----------------------------------------------------------------------------//
 
 void console_init(ctx_t *ctx)
@@ -133,6 +136,18 @@ void console_update(ctx_t *ctx)
 
 //----------------------------------------------------------------------------//
 
+void console_clear(ctx_t *ctx)
+{
+    csn_y = CONSOLE_HEIGHT - 1;
+
+    for (int i = 0; i < CONSOLE_HEIGHT; i++)
+        console_putc(ctx, '\n');
+
+    csn_x = csn_y = 0;
+}
+
+//----------------------------------------------------------------------------//
+
 void console_putat(ctx_t *ctx, char ch, int x, int y)
 {
     SDL_Surface *surf;
@@ -196,8 +211,7 @@ void console_putat(ctx_t *ctx, char ch, int x, int y)
     console_render(ctx);
 }
 
-int csn_x = 0;
-int csn_y = 0;
+//----------------------------------------------------------------------------//
 
 void console_putc(ctx_t *ctx, char ch)
 {
diff --git a/vm/pc/console.h b/vm/pc/console.h
index 3cc0693..fecaa6f 100644
--- a/vm/pc/console.h
+++ b/vm/pc/console.h
@@ -15,5 +15,7 @@ void console_putat(ctx_t *ctx, char ch, int x, int y);
 void console_putc(ctx_t *ctx, char ch);
 void console_update(ctx_t *ctx);
 
+void console_clear(ctx_t *ctx);
+
 void console_handle_input(ctx_t *, SDL_Keycode);
 
diff --git a/vm/pc/main.c b/vm/pc/main.c
index 1510bbd..c519f2a 100644
--- a/vm/pc/main.c
+++ b/vm/pc/main.c
@@ -81,7 +81,10 @@ int main(int argc, char **argv)
 
     main_ctx.r = arch_r;
     main_ctx.i = arch_i;
+
+#ifndef NDEBUG
     main_ctx.dumpsw = 1;
+#endif
 
     //
     // srand