Firmware Download (Aha-1740/1744 Only) - Adaptec AHA-1740A Technical Reference Manual

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Data Rate
1 Mps
500 Kps
300 Kps
250 Kps
DRATESEL Data Rate Select
These bits select the data transfer rate. Reset clears these two bits. Data rates get se-
lected as follows:
1
0
0
1
1

Firmware Download (AHA-1740/1744 Only)

The AHA-1740A/1742A permanently stores both Standard and Enhanced Mode firm-
ware in an EPROM. A microcode upgrade consists of replacing that EPROM with an-
other, and is seldom required. Please contact Adaptec for further information.
The AHA-1740/1744 permanently stores both Standard and Enhanced Mode firm-
2
ware in an E PROM.
The local processor will download the firmware from EEPROM and will run from
RAM. In order to promote maximum data integrity, the firmware calculates check-
sums for itself while not executing commands. The firmware is interrupt driven by
events on the host and SCSI side.
The firmware is programmed into the EEPROM by setting the Enable Prom Write
bit in the PORTPH register. When this is done, reads will come from the RAM and
writes will go to the EEPROM. The firmware is enabled to reprogram when the
CONFIG bit in PORTADDR is set and the firmware download command is given.
The AHA-1740 INTERFACE bit in PORTADDR indicates which code to program.
Provision is also made for loading of new firmware without programming. This defini-
tion is in the AHA-1740 Configuration document.
4-26
Delay
83.00
125.00
125.00
125.00
Bit
0
0
1
0
1
AHA-1740A/1742A/1744
Data Rate (bits/second)
MFM FM
500 250
300 150
250 125
1000 Not defined