Measurement Computing Personal488 rev.3.0 For DOS & Windows 3.Xi - Manual (Page 36)

5. Personal488/MM I. HARDWARE GUIDES
I-20 Personal488 User’s Manual, Rev. 3.0
Interrupt Selection
The GP488/MM interface board may be set to interrupt the PC on the occurrence of certain hardware
conditions. The level of the interrupt generated is set by JP3 on Rev. B boards (JP2 on Rev. A boards).
The GP488/MM interface board adheres to the “AT-style” interrupt sharing conventions. When an
interrupt occurs, the interrupting device must be reset by writing to I/O address
02FX , where X is the
interrupt level (from 0-7). This interrupt response level is set by switches 1, 2, and 3 of SW1 which
must be set to correspond to the JP3 (Rev. B board) interrupt level setting. Interrupt selection for a
Rev. B board is illustrated in the following figure.
Note: The jumper label would read JP2 for Rev. A boards.
DMA Channel Selection
Direct Memory Access (DMA) is a high-speed method of
transferring data from or to a peripheral, such as a
digitizing oscilloscope, to or from the PC’s memory.
The factory default selection is DMA channel 1. Note
that jumper JP2 is used to configure revision B boards
while the jumper labeled JP3 is used to select the DMA
channel on version A boards.
Note: Check your computer documentation to ensure
the selected DMA channel is not being used by
another device. The GP488B/MM board has
circuitry which allows for more than one
GP488/MM board to share the same channel.
Most computers use DMA channel 2 for floppy
disk drives, making that channel unavailable.