PUMA 68F4006/A-70/90/12
ISSUE 4.2 : Nov 1998
DEVICE OPERATION
The following description deals with the device operating in 8 bit mode accessed through CE1,
however status flag definitions shown apply equally to the corresponding flag for each device in the module.
Read Mode
The device has two control functions which must be satisfied in order to obtain data at the outputs
CE1-4 is the power control and should be used for device selection
OE is the output control and should be used to gate data to the output pins if the device is selected.
Standby Mode
Two standby modes are available :
CMOS standby : CE1-4 held at Vcc +/- 0.5V
TTL standby : CE1-4 held at VIH
In the standby mode the outputs are in a high impedance state independent of the OE input. If the device is
deselected during erasure or programming the device will draw active current until the operation is completed.
Output Disable
With the OE input at a logic high level (VIH), output from the device is disabled. This will cause the output pins
to be in a high impedance state.
Autoselect
The autoselect mode allows the reading out of a binary code from the device and will identify the die manu-
facturer and type. This mode is intended for use by programming equipment. This mode is functional over the
full temperature range. The autoselect codes for the first device are as follows :
Type
A14-A16
A1
A0
Code
(HEX)
DQ7 DQ6 DQ5 DQ4 DQ3 DQ2 DQ1 DQ0
Manufacture
Code
X
VIL
VIL
01H
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
1
Device Code
X
VIL
VIH
VIL
20H
Sector
Sector Address VIL
01H*
Protection
* Outputs 01H at protected sector address
To activate this mode the programming equipment must force VID on address A9 . Two identifier bytes may
then be sequenced from each die device outputs by toggling A0 from VIL to VIH. All addresses are dont care
apart from A1 & A0. All identifiers for manufacturer and device will exhibit odd parity with D7 defined as the
parity bit. In order to read the proper device codes when executing the autoselect A1 must be VIL.
Write
Device erasure and programming are accomplished via the command register. The contents of the register
serve as inputs to the internal state machine. The state machine outputs dictate the function of the device. The
register is a latch used to store the commands along with the address and data information required to execute
the command. The command register is written by bringing WE/WE1-4 to VIL while CE1-4 is at VIL and
OE is at VIH.Addresses are latched on the falling edge of WE/WE1-4 while data is latched on the rising edge.
13
MOSAIC [ MOSAIC ]
