Measurement Computing Alpha488 - Manual (Page 3)

Rev. 1.0, 7/96 419-0920
Alpha488 (IEA11) Hardware Guide
Hardware Installation
The following paragraphs explain configuration and physical installation of the interface
card. Software installation and setup are covered in a separate section. After running the
ECU, please make note of the following: the I/O Base Address, the interrupt channel, and
the DMA channel.
The Alpha488 has two DIP switches (S1 and S2), one 22 pin header (IRQ), and two
14-pin headers (DACK and DRQ). The DIP switch settings, along with the arrangement
of the jumpers on the headers, set the hardware configuration.
Default Settings
Notice that S2 and IRQ set the interrupt response level, S1 controls the I/O base address,
and DACK and DRQ select the DMA channel.
Alpha488 I/O Base Address Selection
The I/O base address sets the addresses used by the computer to communicate with the
IEEE 488 interface hardware on the board. The address is normally specified in
hexadecimal and can be 02E1, 22E1, 42E1, or 62E1. The registers of the NEC
µPD7210
IEEE 488 controller chip and other auxiliary registers are then located at fixed offsets
from the base address.
The factory default I/O base address is 02E1. To use a different base address, set S1
according to Figure 1.