Specifications

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Standard Hard Disk Support
Drives connected to the board's Small Computer System Interface (SCSI) can be used to replace
the hard disk controller function normally found in a standard AT. Depending on the hard disk
configuration parameters stored in the board's nonvolatile configuration EEPROM memory (using
SETUP), the board's ROM-BIOS automatically maps hard disk related functions to the SCSI
interface, using the SCSI direct access device Common Command Set for compatibility with a
wide variety of SCSI disk drives. Due to the use of the SCSI Common Command Set, a variety of
devices can be used to supply the hard disk function. Other direct access device options include:
magnetic bubble memory drives, optical storage drives, certain types of tape drives, and solid state
disk drives (EPROM, RAM, NOVRAM).
The board's SCSI Initiator ID (0-7), used in all SCSI bus accesses, is normally read by the ROM-
BIOS from data stored in the board's configuration EEPROM. The Initiator ID value is normally
set using the Ampro SETUP utility, as described in Chapter 3. In normal system configurations,
the default Initiator ID of 7 is recommended because the board's ROM-BIOS performs a SCSI bus
reset on powerup or system reset when this value is used.
The following restrictions apply to the use of the board's SCSI interface and ROM-BIOS support:
Note 1
One restriction of the AT architecture is that addresses during
a DMA block transfer cannot automatically cross page
boundaries (i.e. 64K boundaries for Channels 0-3, or 128K
boundaries for Channels 5-7). However, the board's ROM-
BIOS disk services handle boundary crossing automatically.
Note 2
The board's DMA controller cannot perform 16-bit to 8-bit
transfers, such as between the 16-bit SCSI interface and 8-bit
memory on a bus connected device (e.g. video or I/O
controllers, etc.). In such cases, the software must transfer the
data in two steps: (1) It must perform a 16-bit DMA transfer
between the 16-bit I/O port and 16-bit system memory; and (2)
it must perform a CPU-controlled block move between 16-bit
system memory and the 8-bit bus connected memory. In
particular, it should be noted that the board's ROM-BIOS has
no knowledge of what type of memory (8-bit or 16-bit) is
involved when BIOS functions transfer data between the
board's 16-bit SCSI port and memory. Consequently,
programs which require BIOS functions to transfer data
between a SCSI-connected hard disk and 8-bit RAM on the AT
bus (including video controller display RAM) may require
modification.