Instruction Manual

Chapter 3 Hardware
28 Reference Manual ETX-PVR
19 MEMR* Memory Read – This signal instructs a selected memory device to drive data
onto the data bus. It is active on all memory read cycles.
20 NS Not Supported
21 LA17 Latchable Address 17 – These signals (0-23) must be latched by the resource if
the line is required for the entire data cycle.
22 NS Not Supported
23 LA18 Latchable Address 18 – Refer to LA17, pin-21 for more information.
24 IRQ14 Interrupt Request 14 – Asserted by a device when it has pending interrupt
request. Only one device may use the request line at a time.
25 LA19 Latchable Address 19 – Refer to LA17, pin-21 for more information.
26 IRQ15 Interrupt Request 15 – Asserted by a device when it has pending interrupt
request. Only one device may use the request line at a time.
27 LA20 Latchable Address 20 – Refer to LA17, pin-21 for more information.
28 IRQ12 Interrupt Request 12 – Asserted by a device when it has pending interrupt
request. Only one device may use the request line at a time.
29 LA21 Latchable Address 21– Refer to LA17, pin-21 for more information.
30 IRQ11 Interrupt Request 11 – Asserted by a device when it has pending interrupt
request. Only one device may use the request line at a time.
31 LA22 Latchable Address 22 – Refer to LA17, pin-21 for more information.
32 IRQ10 Interrupt Request 10 – Asserted by a device when it has pending interrupt
request. Only one device may use the request line at a time.
33 LA23 Latchable Address 23 – Refer to LA17, pin-21 for more information.
34 IO16* I/O Chip Select 16 – This signal is driven low by an I/O slave device to indicate
it is capable of performing a 16-bit I/O data transfer. This signal is driven from
a decode of the SA15 to SA0 address lines.
35, 36
GND Ground
37 SBHE* System Byte High Enable – This signal is driven low to indicate a transfer of
data on the high half of the data bus (D15 to D8).
38 M16* Memory Chip Select 16 – This signal is driven low by a memory slave device to
indicates it is cable of performing a 16-bit memory data transfer. This signal is
driven from a decode of the LA23 to LA17 address lines.
39 SA0 System Address 0 – These signals (0 to 19) provide system address bits.
40 OSC Oscillator – This clock signal operates at 14.3 MHz. This signal is not
synchronous with the system clock (SYSCLK).
41 SA1 System Address 1– Refer to SA0, pin-39 for more information.
42 BALE Buffered Address Latch Enable – This signal is used to latch the LA23 to LA17
signals or decodes of these signals. Addresses are latched on the falling edge of
BALE.
43 SA2 System Address 2 – Refer to SA0, pin-39 for more information.
44 NS Not Supported
45 SA3 System Address 3 – Refer to SA0, pin-39 for more information.
46 NS Not Supported
47 SA4 System Address 4 – Refer to SA0, pin-39 for more information.
48 IRQ3 Interrupt Request 3 – Asserted by a device when it has pending interrupt
request. Only one device may use the request line at a time.
Table 3-5. Complete X2 ISA Bus Interface Pin Signal Descriptions (J2) (Continued)