Target (Keil C166)

Xtal (MHz)

Specifies the CPU clock of your device. In most cases this value is identical with the XTAL frequency.

Memory Model

Specifies the C166 compiler memory model. For starting new applications the default SMALL is a good choice.

Operating System

You may use an real-time operating system (RTOS) in your application. Keil offers different versions:

• Advanced RTX166 is a very efficient RTOS which supports preemptive task switching, message and signal passing, semaphores and much more. It includes a Flash File System and extensive TCP/IP support.
• RTX166 Tiny is part of the PK166 Professional Developers Kit and runs on low memory (single-chip systems).
• RTX166 Full is now replaced by Advanced RTX166 and show be not used for new designs. The selection is available for backwards compatibility.

Data Threshold

Allows you to optimize the memory model settings by locating small objects to more optimal memory types. This is useful for the memory models LARGE, HLARGE or COMPACT, HCOMPACT. The default is near, 6 which locates all variables that require not more than 6 bytes to the near memory. Examples for reasonable entries are:

• sdata 10: locate variables with size < 10 Bytes to sdata space. This is typically the XRAM space in a 166 device. Other variables without explicit memory space are in the huge space.
• near 6, idata 2, bdata 2: locate variables with size < 2 Bytes to idata, bit-field structs with single bit members to bdata and variables with size < 6 Bytes to near. Other variables without memory type are in huge.

Use On-chip ...

Specify the usage of the on-chip components which are typically enabled in the CPU startup code. Make sure that the dialog settings are identical with the startup file.

Near Memory

Enlarge RAM and ROM space for fast variable access with 16-bit addresses. It resizes the C166 groups NDATA (RAM) and NCONST (ROM).

External Memory

Specify all external memory areas of the target hardware. RAM is for memory that stores variables. ROM is for areas that store constants and program code (typical EPROM or Flash memory). The information is used to derive linker/locater settings. In addition, you need to configure the CPU startup code to generate the required chip select signals in your hardware.

When testing with Monitor-166 your program code will run in RAM space, but in this dialog you need to specify ROM, otherwise your application has no memory for constants and program code.