Sony AR-B1474, DX4, 486DX manual ISA Bus Signal Description, Name Description

AR-B1474 User¡¦s Guide

2.3.5 ISA Bus Signal Description

Name	Description
BUSCLK [Output]	The BUSCLK signal of the I/O channel is asynchronous to
	the CPU clock.
RSTDRV [Output]	This signal goes high during power-up, low line-voltage or
	hardware reset
SA0 - SA19	The System Address lines run from bit 0 to 19. They are
[Input / Output]	latched onto the falling edge of "BALE"
LA17 - LA23	The Unlatched Address line run from bit 17 to 23
[Input/Output]
SD0 - SD15	System Data bit 0 to 15
[Input/Output]
BALE [Output]	The Buffered Address Latch Enable is used to latch SA0 -
	SA19 onto the falling edge. This signal is forced high
	during DMA cycles
-IOCHCK [Input]	The I/O Channel Check is an active low signal which
	indicates that a parity error exist on the I/O board
IOCHRDY	This signal lengthens the I/O, or memory read/write cycle,
[Input, Open	and should be held low with a valid address
collector]
IRQ 3-7, 9-12, 14, 15	The Interrupt Request signal indicates I/O service request
[Input]	attention. They are prioritized in the following sequence :
	(Highest) IRQ 9, 10, 11, 12, 13, 15, 3, 4, 5, 6, 7 (Lowest)
-IOR	The I/O Read signal is an active low signal which instructs
[Input/Output]	the I/O device to drive its data onto the data bus
-IOW[Input/Output]	The I/O write signal is an active low signal which instructs
	the I/O device to read data from the data bus
-SMEMW[Output]	The System Memory Read is low while any of the low 1
	mega bytes of memory are being used
-MEMR	The Memory Read signal is low while any memory
[Input/Output]	location is being read
-SMEMW[Output]	The System Memory Write is low while any of the low 1
	mega bytes of memory is being written
-MEMW	The Memory Write signal is low while any memory
[Input/Output]	location is being written
DRQ 0-3, 5-7	DMA Request channels 0 to 3 are for 8-bit data transfers.
[Input]	DMA Request channels 5 to 7 are for 16-bit data
	transfers. DMA request should be held high until the
	corresponding DMA has been completed. DMA request
	priority is in the following sequence:(Highest) DRQ 0, 1, 2,
	3, 5, 6, 7 (Lowest)
-DACK 0-3, 5-7	The DMA Acknowledges 0 to 3, 5 to 7 are the
[Output]	corresponding acknowledge signals for DRQ 0 to 3 and 5
	to 7
AEN [output]	The DMA Address Enable is high when the DMA
	controller is driving the address bus. It is low when the
	CPU is driving the address bus
-REFRESH	This signal is used to indicate a memory refresh cycle and
[Input/Output]	can be driven by the microprocessor on the I/O channel
TC [Output]	Terminal Count provides a pulse when the terminal count
	for any DMA channel is reached
SBHE	The System Bus High Enable indicates the high byte SD8
[Input/Output]	- SD15 on the data bus

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