diff --git a/emus/kc85/kc85.zig b/emus/kc85/kc85.zig
index 43ddfea..4983da7 100644
--- a/emus/kc85/kc85.zig
+++ b/emus/kc85/kc85.zig
@@ -1,5 +1,8 @@
 const build_options = @import("build_options");
 const std = @import("std");
+const print = std.debug.print;
+const fs = std.fs;
+const GeneralPurposeAllocator = std.heap.GeneralPurposeAllocator;
 const sokol = @import("sokol");
 const sapp = sokol.app;
 const slog = sokol.log;
@@ -19,7 +22,21 @@ const name = switch (model) {
 };
 const KC85 = kc85.Type(model);
 
+// command line args
+const Args = struct {
+    const Module = struct {
+        mod_type: KC85.ModuleType = .NONE,
+        rom_dump: ?[]const u8 = null,
+    };
+    // optional file to load (.KCC or .TAP format)
+    file: ?[]const u8 = null,
+    // modules to insert into slot 08 and 0C
+    slot8: Module = .{},
+    slotc: Module = .{},
+};
+
 var sys: KC85 = undefined;
+var gpa = GeneralPurposeAllocator(.{}){};
 
 export fn init() void {
     host.audio.init(.{});
@@ -47,6 +64,10 @@ export fn init() void {
         },
     });
     host.gfx.init(.{ .display = sys.displayInfo() });
+    const args = parseArgs(gpa.allocator()) catch {
+        std.process.exit(10);
+    };
+    print("args: {}\n", .{args});
 }
 
 export fn frame() void {
@@ -70,6 +91,9 @@ export fn cleanup() void {
     host.gfx.shutdown();
     host.prof.shutdown();
     host.audio.shutdown();
+    if (gpa.deinit() != .ok) {
+        @panic("Memory leaks detected");
+    }
 }
 
 export fn input(ev: ?*const sapp.Event) void {
@@ -154,3 +178,92 @@ pub fn main() void {
         .logger = .{ .func = slog.func },
     });
 }
+
+fn isArg(arg: []const u8, comptime strings: []const []const u8) bool {
+    for (strings) |str| {
+        if (std.mem.eql(u8, arg, str)) {
+            return true;
+        }
+    }
+    return false;
+}
+
+fn parseArgs(alloc: std.mem.Allocator) !Args {
+    var args = Args{};
+    var arg_iter = try std.process.argsWithAllocator(alloc);
+    defer arg_iter.deinit();
+    _ = arg_iter.skip();
+    while (arg_iter.next()) |arg| {
+        if (isArg(arg, &.{ "-h", "-help", "--help" })) {
+            const help = .{
+                "  -file path -- load .KCC or .TAP file",
+                "  -slot8 name [rom dump path] -- load module into slot 08",
+                "  -slotc name [rom dump path] -- load module into slot 0C",
+                "",
+                "  Valid module names are:",
+                "    m006 - KC85/2 BASIC ROM",
+                "    m011 - 64 KByte RAM",
+                "    m022 - 16 KByte RAM",
+                "    m012 - TEXOR text processor",
+                "    m026 - FORTH development",
+                "    m027 - assembly development",
+            };
+            inline for (help) |s| {
+                print(s ++ "\n", .{});
+            }
+        } else if (isArg(arg, &.{"-file"})) {
+            const next = arg_iter.next() orelse {
+                print("Expected path to .KCC or .TAP file after '{s}'\n", .{arg});
+                return error.InvalidArgs;
+            };
+            args.file = try alloc.dupe(u8, next);
+        } else if (isArg(arg, &.{"-slot8"})) {
+            args.slot8 = try parseModuleArgs(alloc, arg, &arg_iter);
+        } else if (isArg(arg, &.{"-slotc"})) {
+            args.slotc = try parseModuleArgs(alloc, arg, &arg_iter);
+        } else {
+            print("Unknown argument: {s} (run '-help' to show valid args)\n", .{arg});
+            return error.InvalidArgs;
+        }
+    }
+    return args;
+}
+
+fn parseModuleArgs(alloc: std.mem.Allocator, arg: []const u8, arg_iter: *std.process.ArgIterator) !Args.Module {
+    var mod = Args.Module{};
+    const mod_name = arg_iter.next() orelse {
+        print("Expected module name after '{s}'\n", .{arg});
+        return error.InvalidArgs;
+    };
+    const mod_table = .{
+        .{ .name = "m006", .mod_type = .M006_BASIC, .rom = true },
+        .{ .name = "m011", .mod_type = .M011_64KBYTE, .rom = false },
+        .{ .name = "m012", .mod_type = .M012_TEXOR, .rom = true },
+        .{ .name = "m022", .mod_type = .M022_16KBYTE, .rom = false },
+        .{ .name = "m026", .mod_type = .M026_FORTH, .rom = true },
+        .{ .name = "m026", .mod_type = .M027_DEV, .rom = true },
+    };
+    var is_rom_module = false;
+    inline for (mod_table) |item| {
+        if (std.mem.eql(u8, mod_name, item.name)) {
+            mod.mod_type = item.mod_type;
+            is_rom_module = item.rom;
+            break;
+        }
+    }
+    if (mod.mod_type == .NONE) {
+        print("Invalid module name '{s} (see -help for list of valid module names)\n", .{mod_name});
+        return error.InvalidArgs;
+    }
+    if (is_rom_module) {
+        const rom_dump_path = arg_iter.next() orelse {
+            print("Expect ROM dump file path after '{s} {s}\n", .{ arg, mod_name });
+            return error.InvalidArgs;
+        };
+        mod.rom_dump = fs.cwd().readFileAlloc(alloc, rom_dump_path, 64 * 1024) catch |err| {
+            print("Failed to load module rom dump file '{s}'\n", .{rom_dump_path});
+            return err;
+        };
+    }
+    return mod;
+}
diff --git a/zig_notes.md b/zig_notes.md
index fb04fb6..12bfcb9 100644
--- a/zig_notes.md
+++ b/zig_notes.md
@@ -1,5 +1,5 @@
 - Low debug performance may become a problem => investigate!
-  => release=safe is fast
+  => release=safe is fast => PS: not for the KC85 though!
   => inline functions are also inlined in debug mode, but still
      push/pop parameters on stack