diff --git a/assets/bios/tandemport.js b/assets/bios/tandemport.js
new file mode 100644
index 0000000..b488a4b
--- /dev/null
+++ b/assets/bios/tandemport.js
@@ -0,0 +1,68 @@
+con.curs_set(0)
+con.clear()
+let t=`${system.maxmem()>>>10} Kbytes System`
+// 0b_HL where H is top pixel
+// H-bits
+let imgh = [
+[252,0,3,0,0],
+[48,0,3,0,0],
+[51,239,191,102,255],
+[51,237,191,66,219],
+[52,45,161,126,219],
+[54,109,179,124,219]];
+// L-bits
+let imgl = [
+[252,0,3,0,0],
+[51,207,31,60,254],
+[48,109,191,66,219],
+[54,109,179,102,219],
+[52,45,161,96,219],
+[51,237,159,60,219]];
+let imgc = [32,220,223,219]
+for (let y=0;y<imgh.length;y++) {
+for (let x=0;x<imgh[0].length;x++) {
+for (let b=7;b>=0;b--) {
+con.mvaddch(y+1,1+x*8+7-b,imgc[(imgh[y][x]>>b&1)<<1|imgl[y][x]>>b&1])
+}}}
+con.move(8,1+(40-t.length>>1))
+print(t)
+// wait arbitrary time
+for (let b=0;b<system.maxmem()*10;b++) {
+    sys.poke(0,(Math.random()*255)|0)
+    sys.poke(0,0)
+}
+con.clear();
+
+///////////////////////////////////////////////////////////////////////////////
+
+// probe bootable device
+
+var _BIOS = {};
+
+// Syntax: [Port, Drive-number]
+// Port #0-3: Serial port 1-4
+//      #4+ : Left for future extension
+// Drive-number always starts at 1
+_BIOS.FIRST_BOOTABLE_PORT = [0,1]; // ah screw it
+
+Object.freeze(_BIOS);
+
+///////////////////////////////////////////////////////////////////////////////
+
+// load a bootsector using 'LOADBOOT'
+let portNumber = 0;
+let driveStatus = 0;
+while (portNumber < 4) {
+    if (com.areYouThere(portNumber)) {
+        com.sendMessage(portNumber, "LOADBOOT");
+        driveStatus = com.getStatusCode(portNumber);
+        if (driveStatus == 0) break;
+    }
+    portNumber += 1;
+}
+if (portNumber < 4) {
+    eval(com.fetchResponse(portNumber).trimNull());
+}
+else {
+    printerrln("No bootable medium found.");
+}
\ No newline at end of file
diff --git a/src/net/torvald/tsvm/AppLoader.java b/src/net/torvald/tsvm/AppLoader.java
index 7712569..5d8fcfe 100644
--- a/src/net/torvald/tsvm/AppLoader.java
+++ b/src/net/torvald/tsvm/AppLoader.java
@@ -30,7 +30,7 @@ public class AppLoader {
         // val vm = VM(64.kB(), TheRealWorld(), arrayOf(GenericBios))
         //VM vm = new VM(64 << 10, new TheRealWorld(), new VMProgramRom[]{BasicBios.INSTANCE, BasicRom.INSTANCE});
         //VM vm = new VM(64 << 10, new TheRealWorld(), new VMProgramRom[]{OEMBios.INSTANCE, BasicRom.INSTANCE});
-        VM vm = new VM(64 << 10, new TheRealWorld(), new VMProgramRom[]{QuickBios.INSTANCE, BasicRom.INSTANCE});
+        VM vm = new VM(32 << 10, new TheRealWorld(), new VMProgramRom[]{TandemBios.INSTANCE, BasicRom.INSTANCE});
         //VM vm = new VM(64 << 10, new TheRealWorld(), new VMProgramRom[]{TBASRelBios.INSTANCE});
 
         EmulInstance reference = new EmulInstance(appConfig, vm, "net.torvald.tsvm.peripheral.ReferenceGraphicsAdapter", "assets/disk0");
diff --git a/src/net/torvald/tsvm/peripheral/VMProgramRom.kt b/src/net/torvald/tsvm/peripheral/VMProgramRom.kt
index bb03f2d..ff06799 100644
--- a/src/net/torvald/tsvm/peripheral/VMProgramRom.kt
+++ b/src/net/torvald/tsvm/peripheral/VMProgramRom.kt
@@ -68,6 +68,25 @@ object BasicBios : VMProgramRom {
     override fun get(addr: Int): Byte = contents[addr]
 }
 
+object TandemBios : VMProgramRom {
+    private val contents: ByteArray
+
+    init {
+        val bytes = File("./assets/bios/tandemport.js").readBytes()
+        contents = bytes.sliceArray(0 until minOf(65536, bytes.size))
+    }
+
+    override fun readAll(): String {
+        // check if bios is compressed in gzip
+        return if (contents.startsWith(GZIP_HEADER))
+            CompressorDelegate.decomp(contents).toString(VM.CHARSET)
+        else
+            contents.toString(VM.CHARSET)
+    }
+
+    override fun get(addr: Int): Byte = contents[addr]
+}
+
 object BasicRom : VMProgramRom {
     private val contents: ByteArray