P R E L I M I N A R Y

AMD

 

 

SIR2: Local Memory Address Register [7:0] (LMA)

This register is the beginning address on the local bus for system interface I/O transfers that are made to the I/O Data Port. This register automatically increments by

“1” following each read or write operation of any section of the I/O Data Port. (MA[16:15] will be given the values of BSS[4:3] – memory bank select bits.)

Bit

Name

Reset Value

Description

 

 

 

 

7:0

LMA[7:0]

These 8 bits act as Am79C930 memory interface bus address bits

 

 

 

MA[7:0] during system interface accesses to Flash and SRAM

 

 

 

whenever any section of the I/O Data port is read or written. The

 

 

 

LMA[14:0] value is automatically incremented by R1S after any

 

 

 

section of the I/O Data Port is read or written.

 

 

 

Note that these bits are unaffected by any RESET operation.

SIR3: Local Memory Address Register [14:8] (LMA)

This register is the beginning address on the local bus for system interface I/O transfers that are made to the I/O Data Port. This register automatically increments by

“1” following each read or write operation of any of the I/O Data Ports in which the LMA [7:0] register produces a carry out from bit LMA[7].

Bit

Name

Reset Value

Description

 

 

 

 

 

7

ISAPWRDWN

0

Requests the 80188 to enter power down mode if the device is op-

 

 

 

erating in the ISA Plug and Play mode. If already in power down

 

 

 

mode, this bit will indicate 1. If written with a 0 while in power down

 

 

 

mode, power down mode is exited. When written with a 1, value

 

 

 

read will remain 0 until the device actually enters the power down

 

 

 

mode. When written with a 1, the PWRDWN bit generates an inter-

 

 

 

rupt to the 80188, requesting that the 80188 core place the

 

 

 

Am79C930 device into the power down state. The interrupt is sig-

 

 

 

naled in MIR0, bit 5. The PWRDWN bit of SIR3 is identical in func-

 

 

 

tion to the PCMCIA Card Configuration and Status Register's

 

 

 

Power Down bit, but this bit is only functional when the ISA Plug and

 

 

 

Play mode has been selected. This bit is reserved and should be

 

 

 

written as 0 when the PCMCIA mode of operation has been

 

 

 

selected. Reads of this bit produce undefined data when in

 

 

 

PCMCIA mode.

6:0

LMA[14:8]

These seven bits act as Am79C930 memory interface bus address

 

 

 

bits MA[14:8] during system interface accesses to Flash and SRAM

 

 

 

whenever any section of the I/O Data port is read or written. The

 

 

 

LMA[14:0] value is automatically incremented by “1” after any of the

I/O Data Ports is read or written. (Note that MA[16:15] will be given the values of SIR1[4:3] – memory bank select bits.)

Note that these bits are unaffected by any RESET operation.

SIR4: I/O Data Port A (IODPA)

This register directly accesses the Am79C930 memory interface data bus at the memory interface bus address specified by the current value of the LMA registers and the SIR1[5:3] bits. Each read or write operation of any of the I/O Data Ports causes an increment of “1” to the LSB

of the LMA. All four I/O Data Ports will use the same LMA and SIR1[5:3] values. That is, each I/O Data Port is equivalent to the others, except for their location in sys- tem I/O space. Different I/O Data Ports do not imply a built in offset of LMA values.

Bit

Name

Reset Value

Description

 

 

 

 

 

7:0

IODPA[7:0]

These eight bits act as Am79C930 memory interface bus data bits

 

 

 

MD[7:0] during system interface accesses to Flash and SRAM

 

 

 

whenever any section of the I/O Data port is read or written.

 

 

 

 

 

 

 

 

 

Am79C930

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Image 79
AMD Am79C930 manual SIR2 Local Memory Address Register 70 LMA, SIR3 Local Memory Address Register 148 LMA