Справочник Пользователя для Jameco Electronics 2000

The Rabbit is highly code compatible with the Z80 and Z180, and it is easy to port non I/O 
dependent code. The main areas of incompatibility are instructions that are concerned with 
I/O or particular hardware implementations. The more important instructions that were 
dropped from the Z80/Z180 are automatically simulated by an instruction sequence in the 
Dynamic C assembler. A few fairly useless instructions have been dropped and cannot be 
easily simulated. Code using these instructions should be rewritten.

The following Z80/Z180 instructions have been dropped and there are no exact substi-
tutes.

Most of these op codes deal with I/O devices and thus do not represent transportable code. 
The only opcodes that are not processor I/O related are 

, 

, 

, 

, 

, 

, 

, and 

. 

 is not a practical op code. The codes that are concerned 

with decimal arithmetic, 

, 

, and 

, could be simulated, but the simulation is very 

inefficient. (The bit in the status register used for half carry is available and can be set and 
cleared using the 

and 

 instructions to gain access.) Usually code that 

uses these instructions should be rewritten. The instructions 

, 

, 

, and 

 

are repeating compare instructions. These instructions are not very useful because the scan 
stops when equal compare is detected. Unequal compare would be more useful. They are 
difficult to simulate efficiently, so it is suggested that code using these instructions be 
rewritten, which in most cases should be quite easy.

The following op codes are dropped.

The remaining 

 instructions are kept, but the interrupt vector is relocated to a variable 

location the base of which is established by the EIR register. 

 can be simulated by a 

call instruction, but this is not done automatically by the assembler since most of these 
instructions are used for debugging by Dynamic C.

The following instruction has had its op code changed.