Document Number: 001-98285 Rev. *R
S29GL01GS/S29GL512S
S29GL256S/S29GL128S
Software Interface
2. Address Space Maps
There are several separate address spaces that may appear within the address range of the flash memory device. One address
space is visible (entered) at any given time.
Flash Memory Array: the main non-volatile memory array used for storage of data that may be randomly accessed by
asynchronous read operations.
ID/CFI: a memory array used for Cypress factory programmed device characteristics information. This area contains the
Device Identification (ID) and Common Flash Interface (CFI) information tables.
Secure Silicon Region (SSR): a One Time Programmable (OTP) non-volatile memory array used for Cypress factory
programmed permanent data, and customer programmable permanent data.
Lock Register: an OTP non-volatile word used to configure the ASP features and lock the SSR.
Persistent Protection Bits (PPB): a non-volatile flash memory array with one bit for each Sector. When programmed, each
bit protects the related Sector from erasure and programming.
PPB Lock: a volatile register bit used to enable or disable programming and erasure of the PPB bits.
Password: an OTP non-volatile array used to store a 64-bit password used to enable changing the state of the PPB Lock
Bit when using Password Mode sector protection.
Dynamic Protection Bits (DYB): a volatile array with one bit for each Sector. When set, each bit protects the related Sector
from erasure and programming.
Status Register: a volatile register used to display Embedded Algorithm status.
Data Polling Status: a volatile register used as an alternate, legacy software compatible, way to display Embedded
Algorithm status.
ECC Status: provides the status of any error detection or correction action taken when reading the selected Page.
The main Flash Memory Array is the primary and default address space but, it may be overlaid by one other address space, at any
one time. Each alternate address space is called an Address Space Overlay (ASO).
Each ASO replaces (overlays) the entire flash device address range. Any address range not defined by a particular ASO address
map, is reserved for future use. All read accesses outside of an ASO address map returns non-valid (undefined) data. The locations
will display actively driven data but the meaning of whatever 1’s or 0’s appear are not defined.
There are four device operating modes that determine what appears in the flash device address space at any given time:
Read Mode
Data Polling Mode
Status Register (SR) Mode
Address Space Overlay (ASO) Mode
In Read Mode the entire Flash Memory Array may be directly read by the host system memory controller. The memory device
Embedded Algorithm Controller (EAC), puts the device in Read mode during Power-on, after a Hardware Reset, after a Command
Reset, or after an Embedded Algorithm (EA) is suspended. Read accesses and command writes are accepted in read mode. A
subset of commands are accepted in read mode when an EA is suspended.
While in any mode, the Status Register read command may be issued to cause the Status Register ASO to appear at every word
address in the device address space. In this Status Register ASO Mode, the device interface waits for a read access and, any write
access is ignored. The next read access to the device accesses the content of the status register, exits the Status Register ASO,
and returns to the previous (calling) mode in which the Status Register read command was received.
In EA mode the EAC is performing an Embedded Algorithm, such as programming or erasing a non-volatile memory array. While in
EA mode, none of the main Flash Memory Array is readable because the entire flash device address space is replaced by the Data
Polling Status ASO. Data Polling Status will appear at every word location in the device address space.
