ATAM893X-TKHYZ ATMEL [ATMEL Corporation], ATAM893X-TKHYZ Datasheet - Page 5

• Manufacturer Part Number: ATAM893X-TKHYZ
• Description: Flash Version for ATAR080, ATAR090/890 and ATAR092/892
• Manufacturer: ATMEL [ATMEL Corporation]

4.2
4.2.1
4.2.2
4.2.2.1
4680C–4BMCU–01/05
Components of MARC4 Core
Program Memory
RAM
Expression Stack
The core contains ROM, RAM, ALU, program counter, RAM address registers, instruction
decoder and interrupt controller. The following sections describe each functional block in more
detail.
The program memory (EEPROM) is programmable with the customer application program. The
EEPROM is addressed by a 12-bit wide program counter, thus predefining a maximum program
bank size of 4 Kbytes. The lowest user program memory address segment is taken up by a 512-
byte zero page which contains predefined start addresses for interrupt service routines and spe-
cial subroutines accessible with single byte instructions (SCALL).
The corresponding memory map is shown in
be held in ROM and are accessed via the MARC4’s built-in table instruction.
Figure 4-2.
The ATAM893-D contains 256
the expression stack, the return stack and data memory for variables and arrays. The RAM is
addressed by any of the four 8-bit wide RAM address registers SP, RP, X and Y.
The 4-bit wide expression stack is addressed with the expression Stack Pointer (SP). All arith-
metic, I/O and memory reference operations take their operands from, and return their results to
the expression stack. The MARC4 performs the operations with the top of stack items (TOS and
TOS-1). The TOS register contains the top element of the expression stack and works in the
same way as an accumulator. This stack is also used for passing parameters between subrou-
tines and as a scratch pad area for temporary storage of data.
FFFh
7FFh
1FFh
000h
ROM Map
EEPROM
Zero page
(4 K x 8 bit)
4-bit wide static random access memory (RAM). It is used for
Figure
1F8h
1E8h
1E0h
020h
018h
010h
000h
1F0h
008h
4-2. Look-up tables of constants can 0also
page
1E0h
1C 0h
180h
140h
100h
0C 0h
080h
040h
008h
000h
INT7
INT6
INT5
INT4
INT3
INT2
INT1
INT0
$RESET
$AUTOSLEEP
ATAM893-D
5