Vme A21-16 Address Register (8130H); Id Registers (8140H And 8141H); Device Type Registers (8142H And 8143H); Status/Control Registers (8144H And 8145H) - RadiSys EPC - 6A Hardware Reference Manual

CDEN
VME A21–16 Address Register (8130h)
VME A21–16 Address Reg
When an access is performed by the EPC-6A in its "E page" (address range 0E0000–
0EFFFF), the access is mapped onto the VMEbus. The least-significant sixteen of the
VME address bits are provided directly (from the 486DX2), and the remaining 8 (for an
A24 access) bits must come from somewhere else. Six of them come from this register. Bit
7 of this register is used as VME address bit 21, bit 6 as VME address bit 20, ..., and bit 2
as VME address bit 16.
The two low-order bits are reserved RAM bits. On writes, assign them the value 0. For
compatibility with EPC-1, this register is aliased at I/O port addresses 8132, 8134, and 8136.

ID Registers (8140h and 8141h)

ID Register, lower
ID Register, upper
This read-only register adheres to the VXIbus specification. It defines the EPC-6A as a
message-based device and the manufacturer as RadiSys Corporation.

Device Type Registers (8142h and 8143h)

Device Type Reg, lower
Device Type Reg, upper
This register adheres to the VXIbus specification. The first four bits of the upper half
denote that the EPC-6A maps into a 4 MB range in the A24 space when used as a slave.
The remaining ROM bits define the EPC-6A as having a model code of 4044.

Status/Control Registers (8144h and 8145h)

Status/Control Reg, lower
Status/Control Reg, upper
This register adheres to the VXIbus specification and also contains EPC-6A specific bits.
SRIE
RELM
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If set, the flash memory is accessible. If clear, writes to the flash data register
have no effect and reads from it return an unpredictable value.
1
1
1
0
SRIE RELM
SLE
SYSRESET input enable. If set, assertion of VME SYSRESET generates a
reset of the EPC-6A. One use of this bit is having EPC-6A software reset other
VME devices (via bit SYSR) without resetting the EPC-6A.
Bus release mode. If set, the bus release mode is ROR (release on request);
otherwise it is the VXI RONR "fair requester" mode (request on no request).
Altering this bit via the VME-mapped location of this register has no effect.
VMEbus address bits 21–16
1 1 0 1
0 0 0 1
1 0 0 1
0 0 1 1
ARBPRI RDY PASS NOSF
1 SYSR SYSF ARBM
Appendix C: Registers
res res
1 0 0
1 1 1
1 0 0
1 1 1
RSTP
1 1 1
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