Vax 613 0S Instruction Manual download pdf (Page 145)

8.4 NCR 53CF94-2 Registers (600/700/800/900 Models)

The 600/700/800/900 models use the 53CF94-2 SCSI controller device, which

provides these systems with optional Fast SCSI as deﬁned by the ANSI standard,

which provides a data rate up to 10MB/s in synchronous mode.

GPI bit <2> (readable in CIR<6>) reports the SCSI chip oscillator frequency.

A value of 0 indicates that the oscillator is 40 MHz and that Fast SCSI data

transfers have been enabled through the console.

The 53CF94-2 registers are accessed as bits <7:0> of the addressed longword.

Each register is addressed by adding the offset listed in the next table to the

base address listed in the next table. Write operations to the remaining bits are

ignored, and read operations are UNPREDICTABLE. The TURBOchannel byte

mask is ignored write operations to these registers.

Use of these registers is described in Section 9.6.4. For further information, refer

to the NCR 53CF94/96-2 Fast SCSI Controller speciﬁcation.

The registers’ location, format, and contents are:

Base Address Register

600/700/800/900 Models

1.C008.0000 SCSI[0] 53CF94-2 registers

1.C008.0100 SCSI[1] 53CF94-2 registers

OffsetRegister Read Register Write

00 Transfer counter low Transfer count low

04 Transfer counter mid Transfer count mid

08 FIFO FIFO

0C Command Command

10 Status Destination bus ID

14 Interrupt Select/reselect _& timeout

18 Sequence Step Synchronous period

1C FIFO Flags Synchronous offset

20 Conﬁguration 1 Conﬁguration 1

24 Reserved Clock conversion factor

28 Reserved Test mode

2C Conﬁguration 2 Conﬁguration 2

30 Conﬁguration 3 Conﬁguration 3

34 Conﬁguration 4 Conﬁguration 4

38 Transfer counter high

_& ID

Transfer count high

3C Reserved FIFO bottom

TURBOchannel Dual SCSI ASIC 8–13

1 2 ... 140 141 142 143 144 145 146 147 148 149 150 ... 343 344

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Vax 613 0S Instruction Manual Page 145