Measurement Computing PCM-D24/CTR3 rev.3 - Manual (Page 20)

information, all of which is contained in the chip manufacturers data sheet. If you
would like more information, please visit Intel's web site at www.intel.com.
BASE + 8 Interrupt and Clock Source Control
Write control - Read back status
CLK0 CLK1 CKSEL0 CKSEL1 CKSEL2 INT0 INT1 INT2
0 1 2 3 4 5 6 7
Interrupt Source Control
INT2 INT1 INT0 Interrupt source
0 0 0 No Interrupts
0 0 1 External Interrupt
0 1 0 Digital I/O Interrupt from 82C55. PC0 or PC3. See below.
0 1 1 Counter 0
1 0 0 Counter 1
1 0 1 Counter 2
PC0 and PC3 are the outputs of an 82C55 programmed in Mode 1 or Mode 2. These
two modes provide an interrupt output for use in closely coupled parallel interfaces.
To program an 82C55 for Mode 1 or 2 you will need an 82C55 data book. The Com-
puterBoards Universal Library supports Mode 0 only.
The counters on the PCM-D24/CTR3 have quite a bit of programmability. Due to the
architecture of the board, there is additional counter source and chaining flexibility
beyond the standard functions of an 82C54 .
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