	The 3174 changes to the GeometryLink Product
	Peter Ecclesine 20 July 1987

	The GeometryLink Product:

	The GeometryLink is comprised of
		a multibus based 3278 processor (PCOX), based on the CXI
			Model 1A Emulation Adapter for IBM PCs,
		a unix kernel driver (pxd),
		a unix user program (t3279),
		a mainframe tape with VM(SP/XA)
				file transfer (udt)
				Fortvs remote graphics library (RGL, iriscom)
			and MVS(/XA)
				file transfer (irsxfr)
				Fortvs remote graphics library (RGL).
	
	The product was introduced at Autofact '84, and is resold by several
large customers, including
		McDonnell Douglas St. Louis for their KATY application
		LSI Logic Milpitas for chip design
		ATP Campbell for CIMPLEX, mechanical design and manufacturing
Other important users include
		Lockheed Burbank of mechanical design
		Amdahl for chip design
		McDonnell Douglas Long Beach for mechanical engineering.
Note that chip design is a 2D application that requires information management,
and many other vendors have suitable platforms, while MCAE requires fast
floating point 3D display, and SGI has few direct competitors (until fall '87).


	The '3270' Connection:


	The IRIS appears to be a 3278 Model 2 Control Unit Terminal(CUT), and
can be connected to 3274/3276 local and remote controllers. The keyboard and
display operate in the US 87 key keyboard mode and 3279 S2A (base color) mode.
The IRIS can also permit local ansi terminals or TCP/IP connected IRISs to use
the 3278 terminal emulation.
	IBM no longer manufactures the 3270 family, and the 3170 family has
replaced it. The CUT coax protocol is unchanged, but the 3174 is much faster,
and has different command processing algorithms.  The 3174 coax interface is
about 1 volt p-p stronger than the 3274 coax levels.



	GeometryLink Modifications (supporting 3170 and 3270 applications):

	The multibus interface board changes include:
		Firmware changes for the PCOX processor to acknowledge the 3174
			options request ("S" at address 0). The PROMS are in
			sockets.
		Transmit signal level changes - four resistors change
		Receive filter - baby board to low-pass filter the receive. This
			is because many customers are using balums and twisted
			pair wiring, rather than RG62A/U coax.
		Xtal changed to 18.870 MHZ from 18.86792 MHZ - 3174 uses 18.870.
		Buffer RAM - unchanged for IRIS 2000 products, 16kbytes.
			   - expanded for IRIS 3000 products, 64kbytes. The
			     change permits larger mainframe writes, and faster
			     transfers. The modification requires unsoldering
			     the existing RAMs, adding sockets and the 8Kx8 RAM.
			     This takes 0.5 hour to perform.
		Cost of changes - $30 parts + 45 minutes technician's time.

	The unix kernel driver changes include:
		Probe for 64k buffer memory to establish board in use.
		Faster read operation.
		Ioctl to report board in use.
		The kernel driver is 700 lines of C code.

	The unix user program changes include:
		Use of Ioctl to size the read operation.
		Faster read operation.
		Faster write operation.
		Allow ansi terminal and TCP/IP IRIS terminal operation.
		The user program is 12200 lines of C code.

	The mainframe driver changes include:
		Transfer Bid Reply has buffer size and MaxRU parameters.
		The MVS CLIST suport has option for uppercase dsn, lowercase
			irisname.
		The VM file transfer driver is 1600 lines of 370 assembler.
		The MVS file transfer driver is 4000 lines of 370 assembler.
		We have not supported the mainframe RGL since release 3.5, and
			are not changing it to 3174 support.
			The VM RGL driver is 1000 lines of 370 assembler.
