ZBasicRef - page 68 of 172

ZBasic Language Reference

ZX Microcontroller Family

3.8.1 CPU Registers

ZX-24, ZX-40, and ZX-44 Registers

The pre-defined CPU registers for the ZX-24, ZX40 and ZX-44 match those available on the ATmega32

CPU and all are Byte values. Discussion of the use of these registers is beyond the scope of this

document. See the Atmel documentation for a full description. Also, be advised that modifying some of

these registers may severely alter the behavior of the control program, possibly even rendering it

The register value may be accessed by using the register name, from the table below, prefixed by the

keyword Register, e.g. Register.PortC.

CPU Registers for mega32-based ZX Models

Some CPU registers are 16-bit values that have register names in the table above corresponding to the

high and low bytes. For convenience of access, the following UnsignedInteger register names are

available. When reading and writing to these registers, the control program ensures that the high and low

bytes are accessed in the correct order as required by the CPU. Note that UBRR cannot be supported

because the high and low bytes are not adjacent in the I/O address space.

Because the ZX microcontrollers are implemented using a more powerful CPU, some registers available

in BasicX don’t actually exist on the ZX CPU but there are equivalent registers. For compatibility, both

the original register name and the actual register name are supported on similar ZX models. For new

applications, the new register names should be used.

BasicX Register

¹ The serial port baud rate control register is

16-bits wide in the mega32 CPU. The upper

bits are referred to as UBRRH.