Configuration

A number of software flags can be set/cleared to modify the behaviour of the ZLoader/ZIOS. These flags are accessed via the ZLoader C command. Each flag is a boolean value represented in the UI as a YES/NO value. Flags are stored in the RTC NVRAM and so will persist over power cycles.

Typical output from the C command:

> c
00 Install OS:           YES
01 Break handler:        YES
02 Debugger:             YES
03 VT100:                YES
04 Ignore VDU:           NO

The first column is the ID for that parameter and is used to change the value. This is followed by a human readable name and then the value. Current flags are:

ID	Nam	Description
0	Install OS	If YES then when starting an application ZIOS will install service drivers and reserve the top 512 bytes of the first application page for drivers. If not set then the application is responsible for all aspects of hardware control. ZIOS is effectively removed.
1	Break Handler	If YES and Install OS is on then ZIOS will monitor console input for a special break character. For a serial console that will be control C. For the Omega keyboard this will be the F5 key. [Note 1]
2	Debugger	If YES then ZLoader will add support for breakpoints and other debug features [Note 1]
3	VT100	For the Omega keyboard YES tells the driver to translate key presses into their equivalent VT100 codes. If NO then Wordstar key sequences are returned. This value can also be changed via the ZLoader KBD command.
4	Ignore VDU	For systems with both the video and PIO cards. Ignored otherwise. By default if these cards are present ZIOS will install application driver to send data to/from these cards. This isn't always useful and setting this value to YES will cause the console aspects of ZIOS to direct all I/O to/from the serial port.

More flags may be added in future. For reference the flags are stored in the first byte of non-volatile RAM in the i2c connected realtime clock chip. If you don't have the chip installed or there is no battery then configuration changes will be lost on a system restart (reset or power cycle).

Note 1 these flags are only useful when using the ZLoader application for development, using the build in debugger.

Note 2 the NVRAM flag value is ignored for applications loaded from an SDCard via the BOS command. In this case the flag byte in the process description is used in preference to the NVRAM stored value.