diff --git a/src/interrupts.s b/src/interrupts.s
index 699c33c..c271652 100644
--- a/src/interrupts.s
+++ b/src/interrupts.s
@@ -70,6 +70,12 @@ cop_handler_native:
 	; right handler for the particular function being called, without
 	; modifying anything but the X register.
 
+	; Note that if a COP function takes a single 8/16-bit argument, it will be
+	; in A; if it takes two 8/16-bit arguments, they will be in A and Y.
+	; If the function takes more arguments, then the arguments will be packed
+	; into a structure, with the bank of the structure in A, and the
+	; address in that bank of the structure in Y.
+
 	; Now, we do an indirect, indexed jump through the jump table.
 	jmp (.kbank(cop_jump_table),x)
 
@@ -86,14 +92,10 @@ cop_exit:
 
 ; -----------------------------------------------------------------------------
 
-	.extern version_major, version_minor, version_micro
+	.extern version_number
 
 cop_get_version:
-	lda long:version_micro
-	tay
-	lda long:version_minor
-	tax
-	lda long:version_major
+	lda long:version_number
 	cop_rti
 
 ; -----------------------------------------------------------------------------
diff --git a/src/main.c b/src/main.c
index 6c7687f..2809012 100644
--- a/src/main.c
+++ b/src/main.c
@@ -11,9 +11,19 @@
 #include "interrupts.h"
 #include "drivers/vera.h"
 
-const uint16_t version_major = 0;
-const uint16_t version_minor = 1;
-const uint16_t version_micro = 1;
+// This structure essentially divides a uint16_t into four
+// fields, each of which holds a version number.
+struct version_number_s {
+	const uint8_t version_micro: 8;
+	const uint8_t version_minor: 4;
+	const uint8_t version_major: 4;
+};
+
+struct version_number_s version_number = {
+	.version_major = 0,
+	.version_minor = 0,
+	.version_micro = 1,
+};
 
 void
 main(void)