Eisa Configuration Chip (Aic-575); Bmic Bus Interface Chip (82355); Floppy Disk Controller (Aha-1742A Only) - Adaptec AHA-1740A Technical Reference Manual

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EISA Configuration Chip (AIC-575)

The host adapter provides a number of options which may be programmed at configu-
ration time. They are summarized below:
AHA-1540 base port address
Bus on time after preempt
Interrupt definition and selection
Synchronous negotiation enable/disable per target
Disconnection enable/disable per target
Boot drive identification for DOS
BIOS enable, location, and options
The following versions of the ASW-1400 family of software managers support these
features:
ASW-1410, v3.0 and later
ASW-1420, v1.3 and later
ASW-1440, v3.0 and later
ASW-1450, v1.0 and later

BMIC Bus Interface Chip (82355)

This highly integrated ASIC device from Intel controls and interfaces to the EISA
bus. It implements the following main functional blocks:
32-bit bus interface
Adapter FIFO interface
EISA bus protocol logic

Floppy Disk Controller (AHA-1742A Only)

This is implemented by a 82077A single-chip floppy disk drive controller. All drive
control signals are fully decoded and have 40 mA drive buffers with selectable polar-
ity. Signals returned from the drive are sent through on-chip input buffer with hys-
teresis for noise immunity. The integrated analog data separator needs no external
compensation yet allows for a wide motor speed variation with exceptionally low soft
error rates. The microprocessor interface has a 12 mA drive buffer on the data bus
plus 100% hardware register compatibility for standard systems. The 16-byte FIFO
with programmable thresholds is extremely useful in multimaster systems, or
2-4
AHA-1740A/1742A/1744