Installation guide

3 Drivers and Descriptors OS-9 V2.4 on EUROCOM-17

14 Software Manual

3.2 RBF Drivers

The RBF drivers are structured in a physical and logical part.

• scsi17

is the physical driver which deals the NCR53C720 SCSI I/O controller

and has to be loaded if any SCSI I/O is desired.

• rbvccs / rbcvccs

is the logical driver for all harddisks with embedded SCSI controller.

• rbteac / rbcteac

is the logical driver for TEAC FC-1 floppy disk with integrated SCSI

controller.

• rbscfl / rbcscfl

is the logical driver for ELTEC’s SCFL floppy controller. The centronics

port is not supported on EUROCOM-17 and there is no disconnect/

reselect capability.

SCSI commands can be directly sent using the DoDirect SetStat

(SS_DCmd) call of the appropriate driver. The file dodi.c in IO/RBF

contains the C interface to this SetStat entry.

Rbcvccs, rbcteac and rbcscfl are dummy drivers for Snowtops disk

caching software. The disk cache, called DCH, requires two additional

SetStat calls (SS_Cache and SS_CacheXfr) which are supplied by the

dummy drivers. If the dummy driver was invoked with a SS_Cache or

SS_CacheXfr, the request is routed to the cache file manager (CFM). If

there is no request to CFM or DCH is not enabled, the request is directly

passed to the logical driver.

You always have to load the dummy drivers together with the

appropriate logical driver, otherwise your SCSI I/O fails with error

000:221.

Never use any descriptors referring to the same logical driver without

using the dummy driver. Otherwise you risk having two drivers

simultaneously trying to control the same interface.