Fix page movement

hal/paging.go

@@ -112,7 +112,8 @@ func (mmu *MMU) Load(page *Page) {
 
 		// Everything is referenced, we need to remove one
 		if len(mmu.LoadedPages) == 4 {
-			mmu.LoadedPages = mmu.LoadedPages[:2]
+			mmu.movePageToDrive(mmu.LoadedPages[3])
+			mmu.LoadedPages = mmu.LoadedPages[:3]
 		}
 	}
 
@@ -124,13 +125,18 @@ func (mmu *MMU) Load(page *Page) {
 func (mmu *MMU) findEmptyRegisterAddress() *uint16 {
 	var i uint16
 	for i = 0; i < uint16(len(mmu.module.register)/PageSize); i++ {
+		var isTaken bool
 		for _, loadedPage := range mmu.LoadedPages {
 			if *loadedPage.RegisterAddress == i {
+				isTaken = true
+				break
+			}
+		}
+		if isTaken {
 			continue
 		}
 		return &i
 	}
-	}
 
 	return &defaultRegister
 }