DIGITAL-LOGIC Microspace MSM586SEN Technical User Manual page 255

DIGITAL-LOGIC AG MSM586SEN/SEV Manual V1.5E
/IOW, input/output
I/O Write instructs an I/O device to read the data on the data bus. It may be driven by any microprocessor or
DMA controller in the system. This signal is active low.
IRQ[ 3 - 7, 9 - 12, 14, 15], input
These signals are used to tell the microprocessor that an I/O device needs attention. An interrupt request is
generated when an IRQ line is raised from low to high. The line must be held high until the microprocessor
acknowledges the interrupt request.
/Master, input
This signal is used with a DRQ line to gain control of the system. A processor or DMA controller on the I/0
channel may issue a DRQ to a DMA channel in cascade mode and receive a /DACK.
Not available on ELAN520
/MEMCS16, input
MEMCS16 Chip Select signals the system board if the present data transfer is a 1 wait-state, 16-Bit, memory
cycle. It must be derived from the decode of LA17 through LA23. /MEMCS16 should be driven with an open
collector (300 ohm pull-up) or tri-state driver capable of sinking 20mA.
/MEMR input/output
These signals instruct the memory devices to drive data onto the data bus. /MEMR is active on all memory
read cycles. /MEMR may be driven by any microprocessor or DMA controller in the system. When a micro-
processor on the I/0 channel wishes to drive /MEMR, it must have the address lines valid on the bus for one
system clock period before driving /MEMR active. These signals are active low.
/MEMW, input/output
These signals instruct the memory devices to store the data present on the data bus. /MEMW is active in all
memory read cycles. /MEMW may be driven by any microprocessor or DMA controller in the system. When a
microprocessor on the I/O channel wishes to drive /MEMW, it must have the address lines valid on the bus
for one system clock period before driving /MEMW active. Both signals are active low.
OSC, output
Oscillator (OSC) is a high-speed clock with a 70 nanosecond period (14.31818 MHz). This signal is not syn-
chronous with the system clock. It has a 50% duty cycle. OSC starts 100µs after reset is inactive.
RESETDRV, output
Reset Drive is used to reset or initiate system logic at power-up time or during a low line-voltage outage. This
signal is active high. When the signal is active all adapters should turn off or tri-state all drivers connected to
the I/O channel. This signal is driven by the permanent Master.
/REFRESH, input/output
These signals are used to indicate a refresh cycle and can be driven by a microprocessor on the I/0 channel.
These signals are active low.
ELAN520 pullup this signal with 1k Ω Ω Ω Ω
23