Personal488 User's Manual For Windows 95 and Windows NT
Personal488 (with GP488B) 31
Configuring Other Hardware Settings
Configuring the GP488B Interface Wait State
The GP488B is fast enough to be compatible with virtually every PC/XT/AT-compatible computer on
the market. Even if the computer is very fast, the processor is normally slowed to 8 MHz or below
when accessing the I/O channel. If the I/O channel runs faster than 8 MHz, it may be faster than the
GP488B board. If you suspect this is a problem, the computer can be made to wait for the GP488B by
enabling wait states. Increasing the number of wait states slows down access to the GP488B board, but
the overall performance degradation is usually only a few percent.
Configuring the GP488B Interface Internal Clock
The IEEE 488 bus interface circuitry requires a master clock. This clock is normally connected to an
on-board 8 MHz clock oscillator. However, some compatible IEEE 488 interface boards connect this
clock to the PC’s own clock signal. Using the PC clock to drive the IEEE 488 bus clock is not
recommended because the PC clock frequency depends on the model of computer. A standard PC has
a 4.77 MHz clock, while an AT might have a 6 MHz or 8 MHz clock. Other manufacturers’ computers
may have almost any frequency clock. If you are using a software package designed for an interface
board (that derived its clock from the PC clock) and you need to do the same to use GP488B with that
particular software, the clock source can be changed. However, the clock frequency must never be
greater than 8 MHz, and clock frequency must be correctly entered in the Driver488 software.
Summary of Contents for OMB-PER-488/W95
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Page 52: ...46 Driver488 W95 Driver488 WNT Personal488 User s Manual For Windows95 and Windows NT Notes...
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Page 142: ...136 Abbreviations Personal488 User s Manual For Windows95 and Windows NT Notes...
