NEXTSTEP for Intel Processors

Title: DPT 2021/90 and DPT 2021/95 ISA SCSI Adapters
Entry Number: 1476
Last Modified: <<Date June 17, 1997>>

Product Vendor:
Distributed Processing Technology
140 Candace Drive
Maitland, FL 32751
USA

+1 (407) 830 5522 phone
+1 (407) 831 6432 bulletin board system
+1 (407) 260 5366 fax

Keywords: DPT, 2021, SCSI, ISA

Description:
The DPT 2021 SCSI Controller provides a ISA bus to SCSI bus interface. Some of the notable features of this card are:

	Support for up to 64MB of add-on RAM cache
	10MB/sec ISA transfer
	ISA bus mastering
	SCSI-2 and Fast SCSI compliant
	10MB/sec SCSI sync transfer
	Scatter/gather

Release 3.3

See NeXTanswers document 1830_DPT_SCSI_family_Driver_Overview.rtf

Release 3.2
NeXT has tested a DPT 2021 with BIOS revisions 2.A, 2.B, and 2.C and firmware revisions 5A.0, 5B.0, and 5C.0.

Setup and Installation:
The integrated floppy controller for the DPT 2021/95 card is not officially supported by NEXTSTEP. To disable the floppy controller, remove jumper Y20.

If you plan to use your DPT controller with one or more external devices, NeXT recommends enabling External Cable Detection by adding a jumper to Y39.  This will have the effect of reducing the maximum SCSI bus transfer speed to 5MB/s when an external cable is attached.  If you are confident that your cabling can handle a higher transfer rate, you may leave this option disabled.

If the DPT 2021 is not at the end of the SCSI bus, disable its active termination by removing jumper Y16.  For more information on SCSI setup refer to NeXTanswer document 1109_SCSI_Setup.rtfd

The DPT 2021 works correctly with the following default settings in Configure:

DMA Channel: 5
Port Address: 0x170
IRQ Level: 15

However, if you wish to use a different IRQ level to resolve conflicts in your system, NeXT's Quality Assurance group has successfully tested the DPT 2021 using IRQ levels 12 and 14.  Unless the Configure and jumper settings for IRQ level are identical, your system will hang during the boot process.

You shouldn't need to modify any jumper settings except for those listed above.  However, for your reference, the following is a complete description of the DPT 2021 jumpers.  The default settings are marked with an asterisk and illustrated in the diagram.  For more information, see Appendix D of the DPT User's Manual.

Floppy Controller:  Y20  Floppy Controller
ON  Enabled*
OFF  Disabled

SCSI
Termination Power:  Y50  TERMPWR
ON  Enabled*
OFF  Disabled

SCSI BIOS ROM :  Y37  Y36  ROM Address
ON  ON  0xC800*
OFF  ON  0xD800
ON  OFF  0xDC00
OFF  OFF  Disabled

Y38  ROM Size
OFF  8K*
ON  16K

I/O Address:   Y35  Y33  I/O Address
ON  OFF  0x170*
ON  ON  0x1F0
OFF  OFF  0x230
OFF  ON  0x330

DRQ:     Y31  Y32  DMA Channel
ON  ON  DRQ 5*
ON  OFF  DRQ 6
OFF  ON  DRQ 7
OFF  OFF  DRQ 0

IRQ:     Y29  Y30  Interrupt Level
ON  OFF  IRQ 15*
ON  ON  IRQ 14
OFF  ON  IRQ 12
OFF  OFF  Disabled

SCSI ID:    Y25  Y18  Y26  SCSI ID
ON  ON  ON  7*
OFF  ON  ON  6
ON  OFF  ON  5
OFF  OFF  ON  4
ON  ON  OFF  3
OFF  ON  OFF  2
ON  OFF  OFF  1
OFF  OFF  OFF  0

SCSI Termination:  Y16  Termination
ON  Enabled*
OFF  Disabled

External
Cable Detection:  Y39  Cable Detection
ON  Enabled
OFF  Disabled*

DMA Speed Options:  Y12  Y13  Y14  DMA Transfer Rate (MB/s)
OFF  OFF  OFF  10
ON  OFF  OFF  8
OFF  ON  OFF  6.667
ON  ON  OFF  5.7
OFF  OFF  ON  5.0*
ON  OFF  ON  4.4
OFF  ON  ON  4.0
ON  ON  ON  3.0

Y15  Mode  Bus-On Time Bus-Off Time

	OFF	Fastest	12.8s	0.8s*
	ON	Slowest	6.4s	1.6s

LA/SA17-19 Lines:  Y19  Address Lines Driven
ON  SA17-19 and LA17-19*
OFF  Only LA17-19

ISA Bus Mastering
Enable:     Y24  Bus Mastering
ON  Enabled*
OFF  Disabled

Known Problems:
Release 3.1

The DPT 2011 is unsupported in NEXTSTEP Release 3.1.