installed, you can only install the SCSI drive with SCSI ID 0 as drive D:. If two IDE/ST506/ESDI drives already exist, no SCSI drives can be installed as C: or D:. When no IDE/ST506/ESDI drive exists, two SCSI drives with SCSI ID’s 0 and 1 can be installed as drives C: and D:, respectively. When in the DOS environment with the DOS 5 Support enable/disable option enabled, the above limitations do not apply. Refer to the next section for further details on this feature.
For the best performance, enable the Advanced CMOS ROM shadowing option in order to speed up the DC-820B’s operation. This can be done in most system BIOSes by enabling the shadowing of the adapter ROM loca- tion in upper memory (between C8000h and DFFFh) corresponding to the DC-820B’s BIOS ROM address. If more than one DC-820B is installed in the system, only one of them needs to be enabled and shadowed as each host adapter’s ROM commands are identical. Any of the installed adapters’ addresses may be selected — which offers some flexibility when optimizing utilization of UMBs (Upper Memory Blocks) with DOS 5 or third party memory managers. When finished, save the setup information and re-boot the system.
1.6 Running the ECU
The DC-820B requires you to run the EISA Configuration Utility (ECU) for setting the proper Interrupt level, Adapter BIOS address, I/O port address, Direct Memory Access (DMA) channel, and other firmware options. It also supports the DOS 5.0 option to handle up to eight drives. SCSI device options, such as Cacheable, Parity Checking, Synchronous Negotiation, Dis- connect/Reconnect, Mirroring, and maximum transfer rate, can also be set in this utility. Before running this program, copy !TRM0820B.CFG and
TRM0820B.OVL (or ACF20SU.EXE, in case of AMI ECU) from the diskette shipped along with your DC-820B to the ECU diskette provided with the mainboard. Also, make sure that the interrupt levels and addresses of every I/O adapter in your system are different from each other.
For optimum compatibility with the AHA 1540/1542 series, the following guidelines are recommended. In this way, you can use the Adaptec device drivers that are built into the operating systems:
