ZipChip Decompressor

Function Description

The ZipChip Decompressor handles memory transferences of program blocks from off-chip compressed memory to a fast on-chip memory. It is designed for systems that require large amounts of external non-volatile program memory and have processor and a volatile program memory on chip. The ZipChip Decompressor fetches a block of encrypted/compressed program from the external memory, dechyphers and decompresses it using a Zip-based algorithm, and stores the decompressed block into the on-chip memory. ZipChip works like a DMA Controller and is fully compatible with the Intel 8237A DMA Controller. The resulting compressed program in external memory is 30%-40% the size of the original program.

Features

Symbol

Pin Description

Signal name

Mode

Function

RESET

Input

Reset input from the system.

CLK

Input

Clock input.

READY

Input

Enables extended memory read/write cycles.

CS

Input

Chip select. Active LOW. Enables read or write operations of the control registers.

AB[15:0]

I/O

Micropreocessor address bus. Enables access to the internal control registers and provides the address for the memory transfer operations.

MEMRD

Output

Active LOW three-state output used to control data read operations during decompression.

MEMWR

Output

Active LOW three-state output used to control data write operations during decompression.

DB[15:0]

I/O

Microprocessor data bus. Allows the data transfer from external compressed memory to the internal program memory.

HQR

Output

Hold Request to the CPU. Used to request control of the bus.

HLDA

Input

Hold Acknowledged from the CPU indicates that it has relinquished control of the system bus.

Deliverables