Acrosser AR-B9612 - Manual (Page 24)

AR-B9612 User’s Guide
3-5
(3) I/O Channel 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
[Input / Output]
The System Address lines run from bit 0 to 19. They are
latched onto the falling edge of "BALE"
LA17 - LA23
[Input/Output]
The Unlatched Address line run from bit 17 to 23
SD0 - SD15
[Input/Output]
System Data bit 0 to 15
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
[Input, Open collector]
This signal lengthens the I/O, or memory read/write cycle,
and should be held low with a valid address
IRQ 3-7, 9-12, 14, 15
[Input]
The Interrupt Request signal indicates I/O service request
attention. They are prioritized in the following sequence :
(Highest) IRQ 9, 10, 11, 12, 13, 15, 3, 4, 5, 6, 7 (Lowest)
-IOR
[Input/Output]
The I/O Read signal is an active low signal which instructs
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
-SMEMR [Output] The System Memory Read is low while any of the low 1
mega bytes of memory are being used
-MEMR
[Input/Output]
The Memory Read signal is low while any memory 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
[Input/Output]
The Memory Write signal is low while any memory location is
being written