diff --git a/hw/cr16c/virt.c b/hw/cr16c/virt.c
index 225e22a486..1a05ba0956 100644
--- a/hw/cr16c/virt.c
+++ b/hw/cr16c/virt.c
@@ -37,6 +37,9 @@ static void virt_init(MachineState* machine)
 
     create_unimplemented_device("icu", 0xFFFC00, 0xFFFFFF - 0xFFFC00); // interrupt controller unit
 
+    // present on some CR16C implementations (external RAM?)
+    create_unimplemented_device("unknown", 0x1000000, 256*MiB - 16*MiB);
+
     if (machine->firmware) {
         if (!cr16c_load_firmware(&m_state->cpu, &m_state->flash, machine->firmware)) {
             exit(1);