Specifications

CHAPTER 4

Software Support

56 Initializing the Interface Driver

The interface driver for the 12” and 7” PC Compatibility Cards controls communication

between them and the Mac OS (Macintosh Operating System). Applications running on

the Mac OS can use the driver to conﬁgure and control the cards. Applications running

in both environments can use the driver to exchange messages.

This chapter describes the routines that allow you to initialize the driver, conﬁgure the

PC system, make control and status calls, and pass messages between the Mac OS and

the PC driver. You should also refer to Inside Macintosh: Devices for information about

opening and closing the interface driver.

Note

When installed in a Macintosh computer, the 12” and 7” cards

implement PC functions, that is, the functions of a Pentium-based or

5x86-based computer. For the sake of brevity, these functions are

referred to in this chapter as the PC system. Figure 1-1 on page 3

summarizes the PC system functions implemented by the cards.

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Initializing the Interface Driver 4

Before you can use the interface driver, your application must initialize it by calling an

open routine. When initialization is complete, the application calls a close routine. You

can open and close the driver only from the Mac OS. The name of the driver is

"\p.Symbiosis".

Opening the Driver 4

The driver must be open before your application can communicate with it. As described

in Inside Macintosh: Devices, there are various ways of opening drivers. The two principal

ways are OpenDriver and PBOpen. In this case, PBOpen is the preferred way.

When you call the PBOpen routine, it opens the driver speciﬁed by the name parameter,

"\p.Symbiosis". The routine allocates and initializes the driver’s memory, installs the

interrupt handler, and makes patches to the system as needed by the driver. The PBOpen

routine initializes all devices to the null device and puts the PC system into a reset state.

The PBOpen routine fails if the driver cannot allocate enough memory or if it cannot ﬁnd

the 12” or the 7” card.

Closing the Driver 4

When you have ﬁnished communicating with the driver, you can close it using either the

CloseDriver or PBClose routine. It is preferable to use PBClose. When you call the

PBClose routine, it releases all memory allocated to the interface driver, removes the

driver’s interrupt handler, removes any patches installed by the open routine, and puts

the PC system into a reset state.