STC TECHNOLOGY Co.,Ltd.
STC12C5A08/16/32/60
8-bit micro-controller
This document contains information on a new product under development by STC.STC reserves the right to change or discontinue this
product without notice. 2007/12 version A1
Memory
Organization
RAM
There are 1280 bytes RAM built in STC12C5Axx.
The user can visit the leading 128-byte RAM via direct addressing instructions, we name those RAM as
direct RAM
that occupies address space 00h to 7Fh.
Followed 128-byte RAM can be visited via indirect addressing instructions, we name those RAM as
indirect RAM
that occupied address space 80h to
FF
h.
There are extra 1024 bytes RAM can be visited via MOVX @Ri or @DPTR instructions which are
named
external
or
auxiliary
RAM. None of P0 status and P2 status will be affected during MOVX
instruction.
A control bit
EXTRAM
located in SFR
AUXR
.
1
register is to control access of auxiliary RAM. When set,
disable the access of auxiliary RAM. When clear (EXTRAM=0), this auxiliary RAM is the default target
for the address range from 0x0000 to 0x03FF. If EXTRAM=0 and the target address is over 0x03FF,
STC12C5Axx switches to access external RAM automatically. When EXTRAM=0, the content in DPH is
ignored when the instruction MOVX @Ri is executed.
00-7F
RAM, Access it via direct addressing
80-FF
SFR, Access it via direct addressing
80-FF
indirect on-chip RAM,
Access it via indirect addressing
00
80
FF
Address Space for STC12C5Axx RAM
7F
0000-03FF
On-Chip External auxiliary RAM.
http://www.DataSheet4U.net/
datasheet pdf - http://www.DataSheet4U.net/