Samsung KS57C2308 Address Spaces, Overview, General-Purpose Program Memory, Vector Addresses

KS57C2308/P2308/C2316/P2316 ADDRESS SPACES

2 ADDRESS SPACES

PROGRAM MEMORY (ROM)

OVERVIEW

ROM maps for KS57C2 308/C2316 devices are mask programmable at the factory. KS57C2308 has 8K × 8-bit program memory and KS57C2316 has 16K × 8-bit program memory, aside from the differences in the ROM size the two products are identical in other features. In its standard configuration, the device's 8,192× 8-bit (16,384 ×

8-bit) program memory has four areas that are directly addressable by the program counter (PC):

—12-byte area for vector addresses

—96-byte instruction reference area

—20-byte general-purpose area

—8064-byte general-purpose area (KS57C2308)

—16256-byte general-purpose area (KS57C2316)

General-Purpose Program Memory

Two program memory areas are allocated for general-purpose use: One area is 20 bytes in size and the other is 8,064-bytes (16,256-bytes).

Vector Addresses

A 12-byte vector address area is used to store the vector addresses required to execute system resets and interrupts. Start addresses for interrupt service routines are stored in this area, along with the values of the enable memory bank (EMB) and enable register bank (ERB) flags that are used to set their initial value for the corresponding service routines. The 16-byte area can be used alternately as general-purpose ROM.

REF Instructions

Locations 0020H–007FH are used as a reference area (look-up table) for 1-byte REF instructions. The REF instruction reduces the byte size of instruction operands. REF can reference one 2-byte instruction, two 1-byte instructions, and one 3-byte instruction which are stored in the look-up table. Unused look-up table addresses can be used as general-purpose ROM.

Table 2-1. Program Memory Address Ranges

ROM Area Function	Address Ranges	Area Size (in Bytes)
Vector address area	0000H–000BH	12
General-purpose program memory	000CH–001FH	20
REF instruction look-up table area	0020H–007FH	96
General-purpose program memory	0080H–1FFFH (KS57C2308)	8064 (KS57C2308)
	0080H–3FFFH (KS57C2316)	16256 (KS57C2316)

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