src/contextswitcher.pas

@@ -12,15 +12,121 @@
 //  See the License for the specific language governing permissions and
 //  limitations under the License.
 
-{ 
-	ContextSwitcher - Switch Process Contexts when preempted.
-	
-	@author(Kieron Morris <[email protected]>)
+{
+    ContextSwitcher - Custom IRQ0 handler for preemptive context switching.
+
+    Replaces the default ISR_32 with a naked assembly stub that saves the
+    interrupted context (PUSHAD + segment regs), calls a Pascal helper to
+    dispatch timer hooks, send EOI, and run the scheduler, then restores
+    the next process context (or idles) via the returned ESP.
+
+    @author(Kieron Morris <[email protected]>)
 }
 unit contextswitcher;
 
+{$ASMMODE intel}
+
 interface
 
-implementation;
+uses
+    idt, isrmanager, processmanager, proctypes, util, syslog, tracer;
+
+{ Initialise: overwrite IDT gate 32 with our custom ISR. }
+procedure init;
+
+{ No idle ESP variable needed — idle is now a formal process (PID 0)
+  with its SavedESP managed like any other process. }
+
+implementation
+
+{ -----------------------------------------------------------------------
+  do_context_switch_work
+  Pascal helper called from the assembly ISR.  Receives the current ESP
+  (pointing to the GS..EFLAGS save area), dispatches timer hooks, sends
+  EOI, runs the scheduler and returns the ESP for the next context.
+  Uses register calling convention: saved_esp in EAX, result in EAX.
+  ----------------------------------------------------------------------- }
+function do_context_switch_work(saved_esp : uint32) : uint32;
+var
+    next : PProcessContext;
+begin
+    { 1. Save ESP into the current process }
+    processmanager.CurrentProcess^.SavedESP := saved_esp;
+
+    { 2. Dispatch all hooks registered on interrupt 32 (timer hooks).
+         This fires TMR_0_ISR.Main which in turn fires BDA tick,
+         graphics refresh, USB hotplug, etc. }
+    isrmanager.dispatchHooks(32);
+
+    { 3. Send End-Of-Interrupt to the master PIC }
+    outb($20, $20);
+
+    { 4. Pick the next process to run (always returns non-nil; idle as fallback) }
+    next := processmanager.scheduler_pick_next;
+    processmanager.CurrentProcess := next;
+
+    { 5. Return the selected process ESP }
+    do_context_switch_work := next^.SavedESP;
+end;
+
+{ -----------------------------------------------------------------------
+  context_switch_isr
+  Naked assembly ISR that replaces ISR_32 (IRQ0 / PIT timer).
+
+  Stack on entry (pushed by CPU):
+      [ESP+8] EFLAGS
+      [ESP+4] CS
+      [ESP+0] EIP
+
+  We push general-purpose and segment registers, call the Pascal helper,
+  switch ESP to the returned value, pop registers and IRETD.
+  ----------------------------------------------------------------------- }
+procedure context_switch_isr; assembler; nostackframe;
+asm
+    { Save all general-purpose registers (EAX,ECX,EDX,EBX,ESP,EBP,ESI,EDI) }
+    pushad
+
+    { Save segment registers }
+    push ds
+    push es
+    push fs
+    push gs
+
+    { Load kernel data segments }
+    mov ax, $10
+    mov ds, ax
+    mov es, ax
+    mov fs, ax
+    mov gs, ax
+
+    { Call Pascal helper: EAX = current ESP (register calling convention).
+      Returns new ESP in EAX. }
+    mov eax, esp
+    call do_context_switch_work
+    mov esp, eax
+
+    { Restore segment registers }
+    pop gs
+    pop fs
+    pop es
+    pop ds
+
+    { Restore general-purpose registers }
+    popad
+
+    { Return from interrupt }
+    iretd
+end;
+
+{ -----------------------------------------------------------------------
+  init
+  Override IDT gate 32 with our custom ISR.  Must be called AFTER
+  isrmanager.init so that the default gate has been set up first.
+  ----------------------------------------------------------------------- }
+procedure init;
+begin
+    idt.set_gate(32, uint32(@context_switch_isr), $08, ISR_RING_0);
+    tracer.push_trace('contextswitcher.init');
+end;
 
 end.

src/cpu.pas

@@ -22,7 +22,7 @@ unit cpu;
 interface
 
 uses
-    util, RTC;
+    util, RTC, stdio;
 
 type
     PCapabilities_Old = ^TCapabilities_Old;
@@ -113,12 +113,10 @@ var
     CAP_OLD, CAP_NEW : uint32;
 
 procedure init();
+procedure Terminal_Command_CPU(Params : PParamList; stdin_buf, stdout_buf, stderr_buf : POutBuf);
 
 implementation
 
-uses
-    stdio;
-
 procedure getCPUIdentifier;
 var
     id0, id1, id2 : uint32;
@@ -325,7 +323,6 @@ end;
 
 procedure init();
 begin
-    stdio.registerCommand('CPU', @Terminal_Command_CPU, 'CPU Info.');
     CPUID.Capabilities0:= PCapabilities_Old(@CAP_OLD);
     CPUID.Capabilities1:= PCapabilities_New(@CAP_NEW); 
     getCPUIdentifier;

src/driver/bus/usb/usbcore.pas

@@ -158,6 +158,9 @@ procedure init;
 { Unit Tests }
 procedure UnitTest;
 
+{ Terminal command }
+procedure terminal_command_usb(params : PParamList; stdin_buf, stdout_buf, stderr_buf : POutBuf);
+
 implementation
 
 { ========================= Globals ========================= }
@@ -1100,7 +1103,6 @@ begin
     CompletionHookCount := 0;
     for i := 0 to MAX_COMPLETION_HOOKS - 1 do
         CompletionHooks[i] := nil;
-    stdio.registerCommand('USB', @terminal_command_usb, 'USB subsystem information.');
     syslog.logln('USB Core', 'INIT END.');
     pop_trace;
 end;

src/driver/net/l1/net.pas

@@ -100,8 +100,8 @@ end;
 
 procedure send(p_data : void; p_len : uint16);
 begin
-    //push_trace('net.send');
-    //writeToLogLn('L1: net.send');
+    push_trace('net.send');
+    writeToLogLn('L1/NET: send');
     if CBSend <> nil then CBSend(p_data, p_len);
     pop_trace;
 end;
@@ -111,8 +111,7 @@ var
     context : PPacketContext;
 
 begin
-    //push_trace('net.recv');
-    //writeToLogLn('L1: net.recv');
+    push_trace('net.recv');
     context:= newPacketContext;
     if CBNext <> nil then CBNext(p_data, p_len, context);
     freePacketContext(context);
@@ -129,6 +128,7 @@ end;
 procedure init;
 begin
     push_trace('net.init');
+    writeToLogLn('L1/NET: init');
     //l2
     eth2.register;
     //l3
@@ -136,6 +136,7 @@ begin
     ipv4.register;
     //l4
     icmp.register;
+    tcp.register;
     udp.register;
     //l5
     dhcp.register;

src/driver/net/l2/eth2.pas

@@ -46,6 +46,7 @@ var
 
 procedure registerTypePromisc(eType : uint16; RecvCB : TRecvCallback);
 begin
+    push_trace('eth2.registerTypePromisc');
     register;
     if EthTypes[eType] = nil then EthTypes[eType]:= RecvCB;
     Promisc[eType]:= true;
@@ -53,6 +54,7 @@ end;
 
 procedure registerType(eType : uint16; RecvCB : TRecvCallback);
 begin
+    push_trace('eth2.registerType');
     register;
     if EthTypes[eType] = nil then EthTypes[eType]:= RecvCB;
 end;
@@ -93,7 +95,7 @@ var
     buf        : puint8;
 
 begin
-    //writeToLogLn('    L2: eth2.recv');
+    push_trace('eth2.recv');
     buf:= puint8(p_data);
     
     Header:= PEthernetHeader(buf);
@@ -120,6 +122,7 @@ var
 begin
     push_trace('eth2.register');
     if not Registered then begin
+        writeToLogLn('    L2/ETH: register');
         for i:=0 to 65535 do begin
             EthTypes[i]:= nil;
             Promisc[i]:= false;

src/driver/net/l3/arp.pas

@@ -25,7 +25,7 @@ uses
     tracer, lmemorymanager,
     util, lists,
     net, nettypes, netutils,
-    eth2, ipv4;
+    eth2, ipv4, stdio;
 
 type
     PARPCacheRecord = ^TARPCacheRecord;
@@ -41,11 +41,12 @@ procedure sendGratuitous;
 procedure sendRequest(ip : puint8);
 procedure send(hType : uint16; pType : uint16; op : uint16; p_context : PPacketContext);
 function resolveIP(ip : puint8) : puint8;
+procedure terminal_command_arp(Params : PParamList; stdin_buf, stdout_buf, stderr_buf : POutBuf);
 
 implementation
 
 uses
-    stdio, strings;
+    strings;
 
 var
     Registered : Boolean = false;
@@ -96,6 +97,7 @@ var
     hSize, pSize : uint8;
 
 begin
+    push_trace('arp.send');
     if p_context <> nil then begin
         buf:= kalloc(sizeof(TARPHeader));
         hdr:= PARPHeader(buf);
@@ -135,6 +137,8 @@ var
     context : PPacketContext;
 
 begin
+     push_trace('arp.sendGratuitous');
+     writeToLogLn('      L3/ARP: sendGratuitous');
      context:= newPacketContext;
      CopyIPv4(@getIPv4Config^.Address[0], @context^.IP.Destination[0]);
      CopyIPv4(@getIPv4Config^.Address[0], @context^.IP.Source[0]);
@@ -150,6 +154,7 @@ var
     CacheRecord : PARPCacheRecord;
 
 begin
+     push_trace('arp.sendRequestGateway');
      context:= newPacketContext;
      CacheRecord:= findCacheRecordByIP(@getIPv4Config^.Gateway[0]);
      if CacheRecord <> nil then begin
@@ -168,6 +173,8 @@ var
     CacheRecord : PARPCacheRecord;
 
 begin
+     push_trace('arp.sendRequest');
+     writeToLogLn('      L3/ARP: sendRequest');
      context:= newPacketContext;
      CopyIPv4(ip, @context^.IP.Destination[0]);
      CopyIPv4(@getIPv4Config^.Address[0], @context^.IP.Source[0]);
@@ -184,6 +191,7 @@ var
     CacheRecord : PARPCacheRecord;
 
 begin
+    push_trace('arp.resolveIP');
     CacheRecord:= findCacheRecordByIP(ip);
     resolveIP:= nil;
     if CacheRecord = nil then begin
@@ -203,6 +211,7 @@ var
     context      : PPacketContext;
 
 begin
+    push_trace('arp.recv');
     { Get our converted Header }
     Header:= PARPHeader(p_data);
     AHeader.Hardware_Type:= (Header^.Hardware_Type_Hi SHL 8) + Header^.Hardware_Type_Lo;
@@ -298,9 +307,9 @@ procedure register;
 begin
     push_trace('arp.register');
     if not Registered then begin
+        writeToLogLn('      L3/ARP: register');
         Cache:= LL_New(sizeof(TARPCacheRecord));
         eth2.registerTypePromisc($0806, @recv);
-        stdio.registerCommand('ARP', @terminal_command_arp, 'Get ARP Table.');
         Registered:= true;
     end;
     pop_trace;

src/driver/net/l3/ipv4.pas

@@ -26,17 +26,18 @@ uses
     util, strings,
     net, nettypes, netutils,
     lists,
-    eth2;
+    eth2, stdio;
 
 procedure send(p_data : void; p_len : uint16; p_context : PPacketContext);
 procedure registerProtocol(Protocol_ID : uint8; recv_callback : TRecvCallback);
 function  getIPv4Config : PIPv4Configuration;
 procedure register;
+procedure terminal_command_ifconfig(params : PParamList; stdin_buf, stdout_buf, stderr_buf : POutBuf);
 
 implementation
 
 uses
-    arp, stdio;
+    arp;
 
 var
     Registered : Boolean = false;
@@ -46,7 +47,9 @@ var
 
 function  getIPv4Config : PIPv4Configuration;
 begin
+    push_trace('ipv4.getIPv4Config');
     getIPv4Config:= @Config;
+    pop_trace;
 end;
 
 procedure send(p_data : void; p_len : uint16; p_context : PPacketContext);
@@ -57,6 +60,7 @@ var
     buffer : void;
 
 begin
+    push_trace('ipv4.send');
     inc(CurrentID);
     Header.version:= 4;
     Header.header_len:= 5;
@@ -84,6 +88,7 @@ begin
     memcpy(uint32(p_data), uint32(Buffer) + (Header.header_len * 4), p_len);
     eth2.send(Buffer, (Header.header_len * 4) + p_len, $0800, p_context);
     kfree(Buffer);
+    pop_trace;
 end;
 
 procedure recv(p_data : void; p_len : uint16; p_context : PPacketContext);
@@ -95,6 +100,7 @@ var
     len     : uint16;
 
 begin
+    push_trace('ipv4.recv');
     Header:= PIPV4Header(p_data);
     AHeader.version:= Header^.version;
     AHeader.header_len:= Header^.header_len;
@@ -195,6 +201,7 @@ var
 begin
     push_trace('ipv4.register');
     if not Registered then begin
+        writeToLogLn('      L3/IPv4: register');
         for i:=0 to 255 do begin
             Protocols[i]:= nil;
         end;
@@ -205,7 +212,6 @@ begin
         end;
         Config.UP:= false;
         eth2.registerType($0800, @recv);
-        stdio.registerCommand('IFCONFIG', @terminal_command_ifconfig, 'Configure Network Settings.');
         Registered:= true;
     end;
     pop_trace;
@@ -213,6 +219,7 @@ end;
 
 procedure registerProtocol(Protocol_ID : uint8; recv_callback : TRecvCallback);
 begin
+    push_trace('ipv4.registerProtocol');
     register;
     if Protocols[Protocol_ID] = nil then Protocols[Protocol_ID]:= recv_callback;
     pop_trace;

src/driver/net/l4/udp.pas

@@ -25,7 +25,7 @@ uses
     lmemorymanager,
     nettypes, netutils,
     ipv4, net,
-    util;
+    tracer, util;
 
 procedure register();
 function bind(bindContext : PUDPBindContext) : TUDPError;
@@ -71,6 +71,7 @@ begin
             nullend:= true;
         end;
         pseudoBuffer:= kalloc(sizeof(TUDPPseudoHeader) + pseudoSize);
+        push_trace('udp.CalculateChecksum');
         pseudoBuffer8:= puint8(pseudoBuffer);
         pseudoBuffer16:= puint16(pseudoBuffer);
         pseudoBuffer32:= puint32(pseudoBuffer);
@@ -118,6 +119,7 @@ var
 
 
 begin
+    push_trace('udp.send');
     if udpContext <> nil then begin
         size:= p_len + sizeof(TUDPHeader);
         buffer:= kalloc(size);
@@ -152,6 +154,7 @@ var
     context : PUDPBindContext;
 
 begin
+    push_trace('udp.bind');
     result:= tueGenericError;
     if bindContext <> nil then begin
         if Ports[bindContext^.port] = nil then begin
@@ -174,6 +177,7 @@ var
     context : PUDPBindContext;
 
 begin
+    push_trace('udp.unbind');
     result:= tueGenericError;
     if bindContext <> nil then begin
         context:= Ports[bindContext^.port];
@@ -203,6 +207,7 @@ var
     size    : uint16;
 
 begin
+    push_trace('udp.ProcessPacket');
     header:= PUDPHeader(p_data);
     if Ports[switchendian16(header^.DstPort)] <> nil then begin
         context:= PUDPPacketContext(kalloc(sizeof(TUDPPacketContext)));
@@ -245,6 +250,8 @@ var
     Checksum      : uint32;
 
 begin
+    push_trace('udp.register');
+    writeToLogLn('        L4/UDP: register');
     for i:=0 to 65535 do begin
         Ports[i]:= nil;
     end;

src/driver/net/l5/dhcp.pas

@@ -415,7 +415,7 @@ end;
 
 procedure processPacket_NAK(Header : PDHCPHeader; Options : PDHCPOptions);
 begin
-    syslog.logln('DHCP', 'Process NAK.'); 
+    writeToLogLn('          L5/DHCP: Process NAK.');
     { Server provided a NAK, NULL configuration ready for next DISCOVER/Request } 
     nullConfiguration();  
 end;
@@ -429,7 +429,7 @@ var
     cfgopt : void;
 
 begin
-    syslog.logln('DHCP', 'Process ACK.');
+    writeToLogLn('          L5/DHCP: Process ACK.');
     getIPv4Config^.UP:= false;
     
     //Copy new address
@@ -484,7 +484,7 @@ Var
 
 begin
     syslog.logln('DHCP', 'Process OFFER.');  
-
+    writeToLogLn('          L5/DHCP: Process OFFER.');
     { Check the Transaction ID matches our stored ID, discard if not. }
     if Header^.Transaction_ID = Configuration^.Transaction then begin
         syslog.logln('DHCP', 'XID Match');
@@ -566,6 +566,7 @@ var
 
 begin
     tracer.push_trace('dhcp.processPacket.enter');
+    writeToLogLn('          L5/DHCP: processPacket');
     syslog.logln('DHCP','processPacket');
     
     { Give access to header values & process to correct endianness. }
@@ -636,6 +637,7 @@ var
 
 begin
     tracer.push_trace('dhcp.DHCPDiscover.begin');
+    writeToLogLn('          L5/DHCP: DHCPDiscover');
     { Ensure we have a socket bound. }
     if Socket <> nil then begin    
         { Clear any current configuration }
@@ -711,6 +713,7 @@ var
 
 begin
     tracer.push_trace('dhcp.register');
+    writeToLogLn('          L5/DHCP: register');
     syslog.logln('DHCP', 'Register begin.');
     
     { Kalloc our Configuration Data }

src/driver/storage/storagemanagement.pas

@@ -112,6 +112,7 @@ function get_device_list() : PLinkedListBase;
 procedure register_filesystem(filesystem : PFilesystem);
 
 procedure register_volume(device : PStorage_Device; volume : PStorage_Volume);
+procedure disk_command(params : PParamList; stdin_buf, stdout_buf, stderr_buf : POutBuf);
 //function writeNewFile(fileName : pchar; extension : pchar; buffer : puint32; size : uint32) : uint32;
 //function readFile(fileName : pchar; extension : pchar; buffer : puint32; byteCount : puint32) : puint32;
 
@@ -231,7 +232,6 @@ begin
     setworkingdirectory('.');
     storageDevices:= ll_new(sizeof(TStorage_Device));
     fileSystems:= ll_New(sizeof(TFilesystem));
-    stdio.registerCommand('DISK', @disk_command, 'Disk utility');
 
     pop_trace();
 end; 

src/driver/storage/vfs.pas

@@ -104,6 +104,10 @@ function GetDirectories(Handle : uint32; Path : pchar) : PHashMap;
 function PathValid(Path : pchar) : TIsPathValid;
 function changeDirectory(Path : pchar) : TIsPathValid;
 function getWorkingDirectory : pchar;
+function makeAbsolutePathFrom(Path : pchar; BaseDir : pchar) : pchar;
+function resolvePathFrom(Path : pchar; BaseDir : pchar) : TIsPathValid;
+function GetDirectoryListingFrom(Path : pchar; BaseDir : pchar) : PHashMap;
+function changeDirectoryFrom(Path : pchar; BaseDir : pchar; var NewDir : pchar) : TIsPathValid;
 
 //VFS Functions
 function newVirtualDirectory(Path : pchar) : TError;
@@ -608,6 +612,67 @@ begin
     tracer.push_trace('vfs.getWorkingDirectory.exit');
 end;
 
+function makeAbsolutePathFrom(Path : pchar; BaseDir : pchar) : pchar;
+var
+    AbsPath  : pchar;
+    TempPath : pchar;
+begin
+    if Path[0] = '/' then
+        AbsPath := stringCopy(Path)
+    else begin
+        if BaseDir[StringSize(BaseDir)-1] <> '/' then
+            TempPath := StringConcat(BaseDir, '/')
+        else
+            TempPath := stringCopy(BaseDir);
+        AbsPath := StringConcat(TempPath, Path);
+        kfree(void(TempPath));
+    end;
+    makeAbsolutePathFrom := AbsPath;
+end;
+
+function resolvePathFrom(Path : pchar; BaseDir : pchar) : TIsPathValid;
+var
+    TempPath : pchar;
+    AbsPath  : pchar;
+begin
+    TempPath := makeAbsolutePathFrom(Path, BaseDir);
+    AbsPath := evaluatePath(TempPath);
+    kfree(void(TempPath));
+    resolvePathFrom := PathValid(AbsPath);
+    kfree(void(AbsPath));
+end;
+
+function GetDirectoryListingFrom(Path : pchar; BaseDir : pchar) : PHashMap;
+var
+    TempPath : pchar;
+    AbsPath  : pchar;
+begin
+    TempPath := makeAbsolutePathFrom(Path, BaseDir);
+    AbsPath := evaluatePath(TempPath);
+    kfree(void(TempPath));
+    GetDirectoryListingFrom := GetDirectoryListing(AbsPath);
+    kfree(void(AbsPath));
+end;
+
+function changeDirectoryFrom(Path : pchar; BaseDir : pchar; var NewDir : pchar) : TIsPathValid;
+var
+    TempPath : pchar;
+    AbsPath  : pchar;
+    Validity : TIsPathValid;
+begin
+    TempPath := makeAbsolutePathFrom(Path, BaseDir);
+    AbsPath := evaluatePath(TempPath);
+    kfree(void(TempPath));
+    Validity := PathValid(AbsPath);
+    if Validity = pvDirectory then
+        NewDir := AbsPath
+    else begin
+        NewDir := nil;
+        kfree(void(AbsPath));
+    end;
+    changeDirectoryFrom := Validity;
+end;
+
 { Terminal Commands }
 
 procedure VFS_COMMAND_PUSHD(params : PParamList; stdin_buf, stdout_buf, stderr_buf : POutBuf);
@@ -746,11 +811,8 @@ begin
     //outputln('VFS', makeRelative('/test/mydisk/mything', '/test/mydisk'));
     //while true do begin end;
 
-    { Register Terminal Commands }
-    stdio.registerCommand('LS',      @VFS_COMMAND_LS,    'List directory contents.');
-    stdio.registerCommand('CD',      @VFS_COMMAND_CD,    'Set working directory.');
-    stdio.registerCommand('PUSHD',   @VFS_COMMAND_PUSHD, 'Push the working directory.');
-    stdio.registerCommand('POPD',    @VFS_COMMAND_POPD,  'Pop the working directory.');
+    { LS, CD, PUSHD, POPD are now handled as per-terminal builtins
+      in vterminal.pas so each terminal has its own working directory. }
 
     //ht:= PHashMap(Root^.Reference);
     //hashmap.add(ht, 'VDirectory', void(newDummyObject(otVDIRECTORY)));

src/driver/timers/graphicsrefresh.pas

@@ -21,6 +21,7 @@ uses
     uidebug,
     lvgl,
     video,
+    windows,
     syslog;
 
 const
@@ -35,6 +36,7 @@ begin
     TickCounter := TickCounter + 1;
     if TickCounter >= TICKS_PER_FRAME then begin
         TickCounter := 0;
+        windows.reapOrphanedWindows;
         desktop.update;
         uidebug.update;
         lvgl_handler;

src/driver/video/lvgl.pas

@@ -467,6 +467,7 @@ const
     LV_KEY_PREV      = 11;
     LV_KEY_HOME      = 2;
     LV_KEY_END       = 3;
+    LV_KEY_CTRLC     = 128;   { Ctrl+C — terminal interrupt }
 
     { Arc mode }
     LV_ARC_MODE_NORMAL      = 0;
@@ -1861,6 +1862,16 @@ begin
         exit;
     end;
 
+    { Ctrl+C — inject custom key code so focused terminal can handle it }
+    if key_info.is_down_code and key_info.CTRL_DOWN and (key_info.key_code = ord('c')) then begin
+        next_head := (kb_head + 1) mod KB_BUF_SIZE;
+        if next_head <> kb_tail then begin
+            kb_buf[kb_head] := LV_KEY_CTRLC;
+            kb_head := next_head;
+        end;
+        exit;
+    end;
+
     { Map Asuro key codes to LVGL key codes }
     case key_info.key_code of
         $1B: k := LV_KEY_ESC;

src/driver/video/windows.pas

@@ -11,7 +11,7 @@ unit windows;
 interface
 
 uses
-    lvgl, mouse, serial, tracer;
+    lvgl, mouse, serial, tracer, processmanager, proctypes;
 
 const
     MAX_WINDOWS      = 16;
@@ -55,6 +55,7 @@ type
         on_close     : TWinCloseCallback;
         on_resize    : TWinResizeCallback;
         cursor_obj   : Plv_obj;   { cursor to keep on top }
+        owner_pid    : uint32;    { owning process PID; 0 = unowned }
     end;
 
 { Create a new window. Returns window ID (0 = failure). }
@@ -81,6 +82,15 @@ function  getWindowCount: uint32;
 { Set a callback to be notified when a window is resized. }
 procedure setWindowResizeCallback(win_id: uint32; cb: TWinResizeCallback);
 
+{ Assign an owning process to a window.
+  When reapOrphanedWindows detects the process has died, the window
+  is automatically closed via its on_close callback. }
+procedure setWindowOwner(win_id: uint32; pid: uint32);
+
+{ Check all windows for dead owner processes and close them.
+  Called once per frame from graphicsrefresh. }
+procedure reapOrphanedWindows;
+
 implementation
 
 var
@@ -641,6 +651,7 @@ begin
     wins[id].on_close     := closeCB;
     wins[id].on_resize    := nil;
     wins[id].cursor_obj   := cursor;
+    wins[id].owner_pid    := 0;
 
     { Bring to front }
     bringToFront(id);
@@ -698,6 +709,7 @@ begin
     wins[win_id].on_close  := nil;
     wins[win_id].on_resize := nil;
     wins[win_id].cursor_obj := nil;
+    wins[win_id].owner_pid := 0;
 
     tracer.pop_trace;
 end;
@@ -746,4 +758,36 @@ begin
     wins[win_id].on_resize := cb;
 end;
 
+{ ============================================================
+  Public: set window owner PID
+  ============================================================ }
+procedure setWindowOwner(win_id: uint32; pid: uint32);
+begin
+    if (win_id < 1) or (win_id > MAX_WINDOWS) then exit;
+    if wins[win_id].state = wsNone then exit;
+    wins[win_id].owner_pid := pid;
+end;
+
+{ ============================================================
+  Public: reap windows whose owning process has died
+  ============================================================ }
+procedure reapOrphanedWindows;
+var
+    i   : uint32;
+    ctx : PProcessContext;
+begin
+    for i := 1 to MAX_WINDOWS do begin
+        if wins[i].state = wsNone then continue;
+        if wins[i].owner_pid = 0 then continue;
+        ctx := processmanager.findByID(wins[i].owner_pid);
+        if (ctx = nil) or (ctx^.State = psFinished) or (ctx^.State = psError) then begin
+            { Owner is dead — trigger close callback or destroy directly }
+            if wins[i].on_close <> nil then
+                wins[i].on_close(i)
+            else
+                destroyWindow(i);
+        end;
+    end;
+end;
+
 end.

src/drivermanagement.pas

@@ -72,6 +72,8 @@ procedure register_driver(Driver_Name : PChar; DeviceID : PDeviceIdentifier; Loa
 procedure register_driver_ex(Driver_Name : PChar; DeviceID : PDeviceIdentifier; Load_Callback : TDriverLoadCallback; force_load : boolean);
 procedure register_device(Device_Name : PChar; DeviceID : PDeviceIdentifier; ptr : void);
 
+procedure terminal_command_dev(Params : PParamList; stdin_buf, stdout_buf, stderr_buf : POutBuf);
+
 var
     Root : PDriverRegistration = nil;
     Dev  : PDeviceRegistration = nil;
@@ -328,10 +330,6 @@ end;
 procedure init;
 begin
     push_trace('driver_management.init');
-    stdio.registerCommand('DEV', @terminal_command_dev, 'Driver Management Interface.');
-    //stdio.registerCommand('DRIVERSEX', @terminal_command_driversex, 'List all available drivers.');
-    //stdio.registerCommand('DRIVERS', @terminal_command_drivers, 'List loaded drivers.');
-    //stdio.registerCommand('DEVICES', @terminal_command_devices, 'List devices.');
     pop_trace;
 end;
 

src/include/proctypes.pas

@@ -0,0 +1,114 @@
+{
+    ProcTypes - Type definitions for the preemptive process management system.
+
+    Defines process states, system messages, context records, and resource
+    bindings used by processmanager.pas and contextswitcher.pas.
+
+    @author(Kieron Morris <kjm@kieronmorris.me>)
+}
+unit proctypes;
+
+interface
+
+uses
+    stdio;
+
+const
+    { 8 KB per-process kernel stack }
+    PROCESS_STACK_SIZE = 8192;
+
+    { Base quantum multiplier: quantum = Priority * BASE_QUANTUM ticks }
+    BASE_QUANTUM = 8;
+
+type
+    { Forward declaration }
+    PProcessContext = ^TProcessContext;
+
+    { Process states }
+    TProcessState = (
+        psCreated,      { Allocated, stack prepared, not yet scheduled }
+        psRunning,      { Currently executing on the main thread }
+        psReady,        { Runnable but not the current process }
+        psSuspended,    { Paused - will not be scheduled }
+        psAwaiting,     { Blocked on I/O or event - will not be scheduled }
+        psFinished,     { Terminal state - safe to reap }
+        psError         { Unrecoverable error - safe to reap }
+    );
+
+    { System messages delivered to processes }
+    TProcessSysMsg = (
+        smNone,         { No message }
+        smTerminate,    { Graceful shutdown requested }
+        smKill,         { Immediate forced shutdown }
+        smSuspend,      { Pause execution }
+        smResume,       { Resume from suspended }
+        smInput,        { New data available on stdin }
+        smChildExited,  { A child process has exited }
+        smCustom        { User-defined message (payload in MsgData) }
+    );
+
+    { Process entry point - a procedure that IS the process.
+      When this procedure returns, the process is finished. }
+    TProcessEntryPoint = procedure(ctx : PProcessContext);
+
+    { Resource binding types }
+    TResourceKind = (
+        rkSocket,       { TCP/UDP socket }
+        rkTimer,        { A timer hook }
+        rkFileHandle,   { VFS file descriptor }
+        rkCustom        { Arbitrary pointer }
+    );
+
+    { Resource cleanup callback }
+    TResourceCleanup = procedure(handle : void);
+
+    PResourceBinding = ^TResourceBinding;
+    TResourceBinding = record
+        Kind    : TResourceKind;
+        Handle  : void;
+        Cleanup : TResourceCleanup;
+    end;
+
+    { Process context - the core data structure for each process }
+    TProcessContext = record
+        { Identity }
+        ProcessID   : uint32;
+        Name        : array[0..31] of char;
+        ParentID    : uint32;
+
+        { State }
+        State       : TProcessState;
+        ExitCode    : uint32;
+
+        { StdIO - per-process I/O buffers }
+        StdIn       : POutBuf;
+        StdOut      : POutBuf;
+        StdErr      : POutBuf;
+
+        { Entry point }
+        EntryPoint  : TProcessEntryPoint;
+
+        { Context switch state }
+        SavedESP    : uint32;
+        StackBase   : void;
+        StackTop    : uint32;
+
+        { Scheduling }
+        Priority    : uint8;
+        Quantum     : uint16;
+        TicksUsed   : uint16;
+
+        { System messages }
+        PendingMsg  : TProcessSysMsg;
+        MsgData     : void;
+
+        { Resource bindings (PDList of TResourceBinding) }
+        Resources   : void;
+
+        { User-defined state }
+        Local       : void;
+    end;
+
+implementation
+
+end.

src/isr/isrmanager.pas

@@ -31,6 +31,7 @@ type
 
 procedure init;
 procedure registerISR(INT_N : uint8; callback : TISRHook);
+procedure dispatchHooks(INT_N : uint8);
 
 implementation
 
@@ -51,6 +52,15 @@ begin
     end;
 end;
 
+procedure dispatchHooks(INT_N : uint8);
+var
+    i : uint8;
+begin
+    for i:=0 to MAX_HOOKS do begin
+        if Hooks[INT_N][i] <> nil then Hooks[INT_N][i]();
+    end;
+end;
+
 procedure ISR_N(INT_N : uint8);
 var
     i : uint8;