HP 330 Service Information Manual page 120

HP-IB Interface
Hewlett-Packard Interface Bus (HP-IB) is HP's version of the IEEE 488 interface standard.
HP-IB on this board is much like HP-IB implementations on other HP 9000 Series 200/300
conlputers. It uses a TMS9914 HP-IB controller which allows data transfer rates up to 450
Kbytes/second. The TMS9914 is a memory-mapped I/O device which is multiple-mapped
within a 64 Kbyte internal I/O device.
Two registers control hardware which can generate an interrupt as a result of a HP-IB device
responding to a parallel poll. It has the ability to generate an interrupt from a parallel poll
response. For this feature, two registers external to the TMS9914 are used. These registers are
in addition to the two external registers that exist for internal HP-IB interfaces in other Series
200 computers.
All registers associated with the HP-IB are multiple mapped within a 64 Kbyte block of memory
in the internal I/O address range.
One configuration switch for HP-IB system controller is on the system interface board. Located
on the HPIB/RS-232 configuration switch block, the SC switch is set to 1 if the computer is
the system controller or 0 if not.
Information on the TMA9914A and its registers can be found in the 'TMS9914A General Pur-
pose Interface Bus (GPIB) Controller' Data Manual.
Configuration Switches
Three DIP switch blocks on the system interface board configure interfaces for:
• Local Area Network (Table 3-8).
• HP-IB and RS-232 (Table 3-9).
• High-Speed Disc Add-On (Table 3-10).
Refer to the picture of the system interface board, Figure 3-22 for its location.
104
Functional Description