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© National Instruments Corporation 4-1 Lab-NB User Manual
Chapter 4
Register-Level Programming
This chapter describes in detail the address and function of each of the Lab-NB control and status
registers. This chapter also includes important information about register-level programming the
Lab-NB.
Note: If you plan to use a programming software package such as NI-DAQ or LabVIEW
with your Lab-NB board, you need not read this chapter.
Register Access
The Macintosh uses memory mapping to access boards in the system. The following sections
discuss how to access the various registers on the Lab-NB.
Slot Address Space
Each slot in the Macintosh computer is allocated a block of Macintosh memory addresses known
as the slot address space. All I/O boards plugged into Macintosh slots are therefore memory
mapped, and when a board is plugged into a given slot, its registers can be accessed within that
slot address space. The block of memory addresses allocated to each slot depends on the slot
number. The slots are labeled 1 through 6 next to the slot connectors inside the Macintosh II,
IIx, and IIfx. Table 4-1 shows the slot address space for each slot.