Table of Contents

CPU

ace_mode

The CHARON-VAX emulated CPU is configured with the "ace_mode" parameter.

Two VAX CPU implementations are available: the standard VAX instruction decoder and the optional high performance Advanced CPU Emulation mode ("ACE"). The ACE option optimizes VAX instruction interpretation and significantly improves performance. It also requires approximately twice the host memory to store the optimized code.

ACE optimization is performed dynamically during execution. Since it does not need to write optimized code back to disk, ACE provides its full capability instantly. The optimization does not compromise VAX instruction decoding; CHARON-VAX remains fully VAX hardware compatible and completely transparent to the VAX operating systems and applications.

Both CPU implementations passed the HP VAX Architecture (AXE) tests, the standard qualification for VAX instruction execution correctness.

The default VAX CPU mode is determined by the specific CHARON-VAX product license.

This statement enables ACE mode if the CHARON-VAX license permits it. If this statement is omitted from the CHARON-VAX configuration file and the license permits it, "true" is the default. Otherwise "false" is the default. For test purposes the ACE mechanism can be disabled with:

The CHARON-VAX log file displays the status of the ACE option.ACE mode is disabled when the host system does not meet the minimum physical requirements for operation. If the emulator appears not to run at its normal performance, check the log file for a change in ACE mode and verify that sufficient host resources, especially memory, are available.

RAM

The CHARON-VAX memory subsystem is permanently loaded and has the logical name "ram".

size

Example:

The amount of memory is capped at a maximum, defined in the CHARON license key. If the host system cannot allocate enough memory to map the requested emulated memory, CHARON-VAX generates an error message in the log file and reduces its effective memory size.

The following table lists the values of emulated RAM for various hardware models of virtual VAX systems:

TOY

CHARON-VAX maintains its time and date via the "toy" (time-of-year) component. In order to preserve time and date while a virtual system is not running, the TOY component uses a binary file on the host system to store date and time relevant data. The name of the file is specified by the “container” option of the "toy" component.

container

Example:

The CHARON-VAX time zone may be different from that of the host system. Correct CHARON time relies on the correctness of the host system time to calculate the duration of any CHARON “offline” periods. (i.e. while virtual system is not running). Every time CHARON comes on line it calculates a Delta time (the system time is used if there is no TOY file). Therefore, if the host system time is changed while CHARON is not running, the CHARON time may be incorrect when CHARON is restarted and the CHARON time must be set manually.

ROM

The System Flash ROM file conserves specific parameters between reboots.

container

EEPROM

container

Example: 

Auto boot

CHARON-VAX systems may be configured to boot the operating system automatically at start up.

MicroVAX3100, VAXstation 4000, VAX6310 and VAX 4000

Those models boot automatically if correct boot flags are set (and saved in the VAX console files) using the following command:

halt

MicroVAX II, MicroVAX 3600/3900 and VAXserver 3600/3900 

The ROM of the MicroVAX II, MicroVAX 3600, MicroVAX 3900, VAXserver 3600 and  VAXserver 3900 does not allow the VAX console to accept the command setting "auto-boot". Instead, automatic boot on startup can be specified in the CHARON-VAX configuration file as follows:

bdr boot

VAX66x0

xmi boot