Measurement Computing PCM-D24/CTR3 rev.3 - Manual (Page 16)

7 I/O ADDRESS MAP & REGISTER FUNCTIONS
A base address register controls the beginning, or 'Base Address' of the I/O addresses
occupied by the control registers of the PCM-D24/CTR3. In all, 9 addresses are occu-
pied. The base address assigned by CSS is stored in the CB.CBG file by InstaCAL
and read by Universal Library. Please read about installing and using InstaCal.
7.1 CONTROL REGISTERS
Once CSS is installed and a base address has been established, the PCM-D24/CTR3
may be controlled by writing to and reading from the control registers. While it is
possible to write your own control routines for the PCM-D24/CTR3, routines have
been written and are available in Universal Library for DOS and Windows program-
ming languages.
NOTE ON REGISTER PROGRAMMING SUPPORT
While the complete register map is explained here, only very limited support for
assembly language or direct register programming is available. Register level pro-
gramming should only be attempted by experienced programmers. We support the
use of the PCM-D24/CTR3 through high level languages using UniversalLibrary and
the example programs provided.
7.2 PORT ADDRESSES & FUNCTIONS
Read back of control Interrupt & Clock Source Control Base + 8
None 82C54 Control Base + 7
Counter 2 read count data 82C54 Counter 2 Load Base + 6
Counter 1 read count data 82C54 Counter 1 Load Base + 5
Counter 0 read count data 82C54 Counter 0 Load Base + 4
None 82C55 Control Base + 3
Port C Input, Read back output 82C55 Port C Set Base + 2
Port B Input, Read back output 82C55 Port B Set Base + 1
Port A Input, Read back output 82C55 Port A Set Base + 0
READ WRITE ADDRESS
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