.ident	"@(#)qt:README	1.1"
This is a merged version of qt driver which supports both Wangtek PC-36
and Archive SC499-R controller. The controller type is determined at
run time instead of at compile time. The board detection is possible due
to the fact that both controllers are having different register arrangement.

Controller Board Type Detection
_______________________________

The following is a comparison of the controller register map:


	ADDRESS					NAME	
	(HEX)			WANGTEK			ARCHIVE
	_______			_______			________
	300 base	Status/Control/Command		Data/Command
	301			Data			Control/Status
	302			--			start DMA
	303			--			reset DMA


Since the control register of both controllers happens to be different, 
to detect which controller is present one can simply issuing a reset
command to the control register. For example, assuming 300H is the base
address, issuing a reset command to register 300H has no effect to the
ARCHIVE controller and the WANGTEK controller will return with the proper
POR(Power on reset) reset status, and vice versa.

When UNIX is first brought up, the qtinit() will issue a board reset to
determine if the WANGTEK controller is present. If the POR(Power on reset) 
status bit is not set or if the USL(Device Unselected) status is not
cleared within one second, qtinit() will assume the WANGTEK controller
is not installed and try to test for ARCHIVE controller. If there is no
response agian within 5 seconds(ARCHIVE controller performs power on diagnostic,
it will take up to 5 seconds to complete), then the qt driver will 
assume no controller is present and disable the driver.

Three files: qt.h, globals.h and qt.c are modified to provide this new
feature.


150 MB Tape Drive Support
_________________________

The 150 MB 1/4-inch cartidge streaming tape drive is the successor of the
60 MB drive. It is available with the same QIC-02 interface and supports
QIC-24/120/150 formats for total backward compatibility. Again, both 
WANGTEK and ARCHIVE are the major suppliers of this product. The following
is a table shows the differences between a 60 MB drive and a 150 MB drive:


	FEATURE				SPECIFICATION
			Wangtek	5099EN24		5125EQ/5150EQ
			Archive	2060L			2150L
	____________________________________________________________
	Formatted Capacity	60 MB			120/150 MB

	Track Format		9-Track			18- or 15-track

	Flux Density		10,000 frpi		12,500 frpi

	Data Density		8000 bpi		10,000 bpi

	Recording Format	QIC-24			QIC-120 or QIC-150

	Qualified Tape		DC300XLP or DC600A	DC600A or DC600XTD

	Read Compatibility	QIC-24			QIC-24, QIC-120, or
							QIC-150


Similar to the 60 MB drive, both WANGTEK and ARCHIVE 150 MB drives are 
fully compatible and totally interchangeable. However, the 150 MB
tape drive will not work with the existing 60 MB QIC-02 controller.
Both WANGTEK and ARCHIVE require a new controller to support the 150 MB
tape drive even though the new drive use the same QIC-02 interface. 
Fortunately, the new controllers from both firms still maintain the same
host interface, hence the existing qt driver will work with the 150 MB drive
without modifications.

The following diagram lists all the possible drive and controller 
configuration:



	             |--- PC-36 -----\ /--- 5099EN24
	             |                X
	             |--- SC499-R ---/ \--- 2060L
	             |
	qt driver  --|
	             |
	             |--- EV-811 ----\ /--- 5125EQ/5125EQ
	             |                X
	             |--- SC402  ----/ \--- 2150L
