Diamond Systems Low-Power PC/104 CPU Board With ZFx86 Processor Failsafe Mode / BIOS Recovery

6.5Failsafe Mode / BIOS Recovery

The ZFx86 failsafe feature consists of a small command interpreter built in to the ZFx86 CPU chip. The ZFx86 contains a ROM with the command interpreter as well as an 8KB RAM. It may be used to power up the system and download the BIOS to recover from situations in which the BIOS accidentally becomes corrupted or erased. The failsafe feature is used in the factory to program the BIOS in new Prometheus-LC boards for the first time.

To enable the failsafe feature when the panel board is not used, install a jumper between pins 1 and 3 of J6 on Prometheus. To enable failsafe feature when the panel board is used, press the ZFIX button on the panel board while pressing and releasing the Reset button (the ZFIX button must be released after the Reset button is released). During the next system reset, the board will power up to the failsafe boot ROM and provide user I/O through COM1. At this point the DSC utility program ZFTERM.EXE may be used to download the BIOS to the board. See the information in the \Utilities\BIOS Recovery folder of the Prometheus-LC files area of the DSC customer CD for instructions on using this program.

6.6Flash Memory

Prometheus-LC contains a 1Mbyte 16-bit wide flash memory chip for storage of BIOS and optional user files. The BIOS occupies the upper 256Kbytes, leaving the rest available for user applications.

6.7Backup Battery

Prometheus-LC contains an integrated RTC / CMOS RAM backup battery. The battery is located adjacent to the PC/104 bus connector J1. This battery has a capacity of 30mAH and will last approximately 2 years in power-off state. The battery is activated for the first time during initial factory configuration and test. Thus the age of the battery can be determined by inspecting the date label on the board.

6.8System Reset

Prometheus-LC contains a chip to control system reset operation. Reset will occur under either of two conditions:

♦User causes reset with a ground contact on the Reset input

♦Input voltage drops below 3.0V.

The ISA Reset signal is an active high pulse with a duration of 200ms.

Prometheus-LC CPU User Manual V1.0 Page 19