NAME

ise − Integral SCSI and Ethernet Daughtercard

DESCRIPTION

The Integral SCSI and Ethernet Daughtercard is a small, low cost, plug in I/O expansion module.  This expansion module provides access to SCSI and Ethernet interfaces without consuming two slots of an HVME/VME I/O chassis.  The card uses advanced VLSI coprocessors to control the SCSI bus and the Ethernet interface relieving the main processor(s) from these tasks.  However, the card has no RAM for data buffering.  Instead, it uses the system memory resources via DMA to buffer data, and to communicate with its drivers. 

A system may have at most one ISE daughtercard, and it must be attached to the CPU board in lowest numbered HVME slot.  It attaches to the CPU motherboard in a sandwich fashion to upper frontal portion of the CPU motherboard.  A single 64 pin connector is provided with frontal access from which the 50 pin SCSI cable and a 15 pin Ethernet transceiver cables emerge (one pin of the ethernet transceiver is not connected).  When supplying device names to the console processor or standalone software, you should controller number 0 and bus number 0.  A valid device name for a disk device on the integral SCSI might be dsk(0,1,0,0) which would refer to controller 0, drive 1 (SCSI bus ID), partition 0, and bus 0. 

Though they reside on the same card, the integral SCSI interface and the integral Ethernet interface are logically two separate components.  Correspondingly, we treat them as two separate resources that are controlled by two separate device drivers.  They are also configured as two separate controllers in /etc/master system configuration file.  Integral SCSI Interface

The controller of the integral SCSI interface is a special purpose coprocessor chip, NCR 53C700 SCSI I/O Processor.  This is a third generation SCSI bus controller chip that manages most activity of the SCSI bus without CPU intervention.  It does so by virtue of its own instruction set.  The SCSI interface device driver simply starts the chip executing a small "program" that handles the normal activities of the SCSI bus until a command is completed or some other exceptional event occurs on the SCSI interface, at which time a CPU is interrupted.  The device driver interrupt routine then schedules the next activity for the SCSI interface and restarts the SCSI processor with the correct "program".  These "programs" are written in a scripting language defined by NCR and then assembled as data into the system device driver.  SCSI Devices and Drivers

Devices connected to the Intergal SCSI interface use the same CX/UX device drivers as devices connected to the HVME SCSI Adaptor (HSA), the Generic Disk Driver gd(7) and the Generic Tape Driver gt(7).  These generic drivers use another level of software to control the hardware specific portions of the interfaces.  These are called the driver "Interface Modules".  The generic disk driver supports interface modules for the HVME Disk Controller (HDC) as well as for the HSA and the Integral SCSI.  Respectively, these are the hd, hs, and is interface modules. 

The is interface module was designed to be compatible with the hs interface module.  Indeed, it supports the same peripheral set, and is implemented using many of the same algorithms. As with the HSA, the is interface module was designed to work with SCSI devices that support the Common Command Set (CCS) extensions to the SCSI-1 standard.  Most disk and tape drive vendors now supply embedded SCSI controllers that support the CCS extensions.  The CCS extensions have also been incorporated into the more recent SCSI-2 standard, implying those devices which support the SCSI-2 standard may work with the is interface module as well.  However, drives not supporting the SCSI-1 standard plus the CCS extensions are not likely to operate correctly with the integral SCSI interface without some customization of system software. 

While the Integral SCSI software has been tested with a wide variety of devices, it has only been extensively tested with the standard devices available directly from Harris.  Because the compatibility testing done with third party SCSI devices is not nearly as complete as the testing that occurs with standard Harris products, Harris does not guarantee that any third party SCSI device will function correctly when connected to its integral SCSI interface.  Harris can provide some limited technical assistance to integrators experiencing difficulties with non-Harris devices, however, the variations in third party SCSI hardware are too great to guarantee that all devices will function properly with the Integral SCSI hardware and software.  Integral SCSI Hardware Configuration

The SCSI standard allows for 8 devices address on the SCSI bus called SCSI bus IDs.  The integral SCSI software can support any combination of up to 7 SCSI target devices since it must reserve a bus ID for itself.  By convention, SCSI bus ID 7 is reserved for the integral SCSI interface and should not be used by any target device.  Also by convention, disk devices are generally assigned first from SCSI bus ID 0 up to SCSI bus ID 6.  Tape devices are generally assigned SCSI bus IDs 5 down to SCSI bus ID 0.  SCSI bus ID 6 is only assigned if all other IDs are already assigned.  The /etc/master system configuration file identifies which bus IDs correspond to which disk/tape units.  An excerpt from a configuration file is included below.  Additional limits of 32 disk units of all types and 16 tape units of all types are imposed by the CX/UX system software.  Integral Ethernet Interface

The Ethernet coprocessor is an Intel 82596DX Network Coprocessor chip.  This chips also represents the third generation of intelligent LAN coprocessors.  It controls completely the management of an Ethernet/IEEE 802.3 link level interface.  It supports an extremely flexible frame structure for both incoming and outgoing frames.  This eliminates the need for the interface driver to copy frame data between buffers since the chip can send/receive frame data directly into the system memory buffer structures that are passed down/up to the upper level network protocols.  The interface driver communicates with the controller chip through a shared memory area with pointers to receive buffers and transmit commands blocks that the chip is working with.  The chip interrupts the CPU at the only after it has completed frame reception or transmission, or if stops receiving because it has run out of memory buffers to receive into.  Integral Ethernet Hardware Configuration

The Integral Ethernet hardware requires no special configuration.  Each ISE daughtercard has a unique Ethernet station address in prom on the card.  Of course, this address can be overridden with the enconfig(1m) program to be any valid Ethernet station address.  Software Configuration

Disk and tape drives connected to the integral SCSI are configured as any other disk or tape drive except that the controller name is is.  Similarly, the integral Ethernet interface is configured as like any other network interface except the device name is ie.  The following excerpt from the /etc/master system configuration file illustrates a how to configure the integral SCSI with two disks and tape drive as well as the how to configure the integral Ethernet interface. 

 ...
 ...
controlleris0at vba0 csr 0x97200000vector isintr
 diskdsk0at is0 drive 0
diskdsk1at is0 drive 1
tapemt0at is0 drive 5
  deviceie0at vba0 csr 0x97100000vector ieintr
  ...
 ...

CX/UX Device Drivers

Like all disks on a CX/UX system, disks configured on the integral SCSI interface will be accessed via the Generic Disk driver (gd(7)).  The advantage of this approach is that programs that could interact with potentially many disk device drivers will instead interact with a single common device driver.  This results in a high degree of compatibility for both user and system level software.  The use of a common driver also insures consistency in device naming and numbering conventions, and facilitates almost identical system administration procedures such as formatting, partitioning, etc.  Refer to gd(7) for more information about the generic disk driver, and its facilities. 

Similarly, all tapes (with the exception of Pertec interface tapes configured on a Xylogics tape controller) will use the Generic Tape driver (gt(7)).  Again, user and system level software see a single common driver interface that insures application portability among different tape drives as well as common administration procedures.  Refer to gt(7) for more information about the generic tape driver, and its facilities. 

The Integral Ethernet is controlled by a network interface driver ala 4.3 BSD TCP/IP.  This driver received packets from IP sends them to the interface.  Received frames are passed up to host based IP software directly.  Performance

The integral SCSI interface can accommodate both synchronous and asynchronous transfer modes on the SCSI bus.  It can achieve transfer rates up to 5 Mbytes/sec or more on the SCSI bus.  However, in practice, the maximum transfer rate of the SCSI target device with which the interface communicates is the maximum achievable transfer rate. 

SEE ALSO

config(1M), master(4), format(1M), hdc(7), gd(7), gt(7)

CX/UX Administrator’s Reference