IBM 6268, 6288, 6278 manual Hard disk drives and controller, Diskette, System compatibility

Chapter 6. System compatibility

3.Sends the EOI

4.Waits one I/O delay

5.Enables the interrupt through the Set Interrupt Enable Flag command

Hardware interrupt IRQ9 is defined	as the	replacement interrupt	level	for the casc
Program interrupt sharing is implemented	on IRQ2, interrupt hex 0A.		The	following process
maintain compatibility with the IRQ2	used by	IBM Personal Computer	products:

1. A device drives the interrupt request active on IRQ2 of the channel.

2. This interrupt request is mapped in hardware to IRQ9 input on the second interru

3.When the interrupt occurs, the system microprocessor passes control to the IRQ9 interrupt handler.

4. This interrupt	handler performs an EOI command to the second interrupt controller a
to the IRQ2	(interrupt hex 0A) interrupt handler.

5. This IRQ2 interrupt handler, when handling the interrupt, causes the device to re request before performing an EOI command to the master interrupt controller that f the IRQ2 request.

Diskette		drives and	controller
The following figures			show		the reading,	writing, and formatting capabilities of the di
Figure		17. 3.5-inch diskette drive reading, writing, and formatting capabilities
Diskette	drive type			720	KB Mode		1.44 MB Mode
1.44	MB	drive		RWF			RWF
2.88	MB	drive		RWF			RWF

Copy protection The following methods of copy protection might not work in systems using

1.44MB diskette drive.

Ÿ Bypassing BIOS routines

– Data transfer rate: BIOS selects the proper data transfer rate for the medi

– Diskette	parameter	table: Copy protection, which creates its own diskette parame
not work	in these	drives.

Ÿ Diskette drive controls

–	Rotational	speed: The	time	between	two events in a diskette drive is a functio
–	Access time: Diskette		BIOS	routines	must set the track-to-track access time for
	of media	that are	used	in the	drives.

– ‘Diskette change’ signal: Copy protection might not be able to reset this signal.

ŸWrite-current control: Copy protection that uses write-current control does not work,

controller selects the proper write current for the media that is being used.

Hard disk drives and controller

Reading from and writing to the hard disk is initiated in the same way as in IBM products; however, new functions are supported.

Chapter 6. System compatibility23