hi, due A51 datasheet, it says: DS The DS directive reserves a specified number of bytes in a memory space. The DS directive has the following format:
label: DS expression
?XD?VAR_XDATA SEGMENT XDATA RSEG ?XD?VAR_XDATA VAR1: DS 0x10 VAR2: DS 0x10
?XD?VAR_XDATA SEGMENT XDATA RSEG ?XD?VAR_XDATA VARS: DS 0x20 VAR1 XDATA VARS+0x00 VAR2 XDATA VARS+0x10