Themis TA64, Руководство по оборудованию

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4-5
Themis Computer
4—Universe II Description
VMEbus Interface
4.2.4 VMEbus First Slot Detector
As defined by the VME64 specification, the Universe II samples the BG3IN* right
after the reset to determine if the TA64 resides in slot 1. If the BG3IN* is sampled
low right after the reset, the TA64 board becomes the SYSCON. Otherwise the
SYSCON Module of the Universe II is disabled. The software can set or clear the
SYSCON bit the MISC_CTL register of the Universe II. The definition of the
MISC_CNT register is provided in
Table 4-1 on page 4-5. The offset of this register
is 0x404.
Table 4-1.
Universe II Miscellaneous Control Register (MISC_CTL)
a
BIts Name Description
Reset
State
Access
[31:28] VBTO
VMEbus Time-out:
0000 = Disable; 0001 = 16
μ
s; 0010 =
32 μ
s; 0011 =
64
μ
s;
0100 = 128
μ
s; 0101 = 256
μ
s; 0110 = 512
μ
s;
0111 = 1024
μ
s; Others = RESERVED
0011
R/W
26 VARB
VMEbus Arbitration Mode: 0 = Round Robin; 1 = Pri-
ority
0
R/W
[25:24] VARBTO
VMEbus Arbitration Time-out
00 = Disable Timer; 01 = 16
μ
s (minimum value of 8
μ
s, due to the 8
μ
s clock granularity); 10 = 256
μ
s;
others - RESERVED
01
R/W
23 SW_LST PCI Reset: 0 = no effect; 1 = initiate PCI bus LRST* 0 W
22 SW_SYSRST
Software VMEbus SYSRESET:
0 = no effect; 1 = Initiate VMEbus SYSRST
0
W
20 BI
BI- Mode: 0 = Universe II is in BI-mode;
1 = Universe II is not in BI mode
Power-up
Option
R/W
19 ENGBI
Enable Global BI-mode Initiator:
0 = Assertion of VIRQ1 ignored; 1 = Assertion of
VIRQ1 puts the Universe II in BI-mode
0
R/W
18 RESCIND Unused on the Universe II 1 R/W