diff --git a/Makefile b/Makefile
index d03e8ea..fc0a083 100644
--- a/Makefile
+++ b/Makefile
@@ -11,7 +11,7 @@ else
 debug_flags := $(debug_flags) -Og -feliminate-unused-debug-symbols
 tui_library_flags := -lncursesw
 endif
-common_source_files := field.c mark.c sim.c
+common_source_files := field.c mark.c bank.c sim.c
 tui_source_files := $(common_source_files) tui_main.c
 cli_source_files := $(common_source_files) cli_main.c
 
diff --git a/bank.c b/bank.c
new file mode 100644
index 0000000..e701de2
--- /dev/null
+++ b/bank.c
@@ -0,0 +1,10 @@
+#include "bank.h"
+
+void bank_init(Bank* bank) {
+  bank->data = NULL;
+  bank->capacity = 0;
+}
+
+void bank_deinit(Bank* bank) {
+  free(bank->data);
+}
diff --git a/bank.h b/bank.h
new file mode 100644
index 0000000..3294f69
--- /dev/null
+++ b/bank.h
@@ -0,0 +1,16 @@
+#include "base.h"
+
+typedef struct {
+  U32 grid_index;
+  U8 size;
+} Bank_entry;
+
+typedef struct {
+  char* data;
+  Usz capacity;
+} Bank;
+
+typedef char* Bank_cursor;
+
+void bank_init(Bank* bank);
+void bank_deinit(Bank* bank);