I/O Expansion - HP 743 Series Technical Reference Manual For Oems

I/O Expansion

The Model 743 and Model 744 board computers are capable of accepting expansion adapters
allowing greater functionality through expansion I/O cards. The PMC bridge adapter (for
HP-UX systems only) occupies an additional VME slot directly above or adjacent to the
board computer, and has two sites for industry standard +5V signalling PMC cards. The
PMC expansion adapter occupies another VME slot adjacent to or above the PMC bridge
adapter, and provides two additional sites for PMC cards. The GSC expansion adapter has
two sites for GSC expansion cards, and occupies one VME slot adjacent to or above the
board computer. The PMC adapters and the GSC adapter cannot function together.
HP provides three GSC solutions for expanded I/O:
• 8-plane color graphics controller
• FWD SCSI controller
• ATM network controller
Fast, Wide, Differential SCSI (GSC) (HP-UX only)
20 MB/sec data transfer rates.
The internal, removable, differential bus terminators allow the card to be located at either end
or between the ends of a SCSI bus. The host SCSI ID for the port is set by the user by way of
the 4-position address selector DIP-type switch.
By default, the FWD SCSI card terminates one end of the SCSI bus by using removable ter-
minator resistors that are on the card. Remove these terminator resistors if the card is in the
middle of the bus.
Table 1-23 summarizes the FWD SCSI interface specifications.
Table 1-23 FWD SCSI Interface Specifications
Connector type
Controller
Data rate
Device limits
Maximum external cable length
Type
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Model 743 and Model 744 VME Board Computers
The FWD 16-bit implementation supports
SCSI-3, 68-pin high-density thumbscrew
NCR 53C720
Asynchronous, 10 MB/second
Synchronous, 20 MB/second
15 internal and/or external devices
25 meters (82 feet)
SCSI-II, 16-bit
General Information
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