Commodore 128 Programmer's Reference Manual page 686

676 COMMODORE 128
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APPENDIX K
PART I—COMMODORE 128 CP/M r (
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This appendix explains each CP/M BIOS, 8502 BIOS and User Function routine and ^
how to call each in Z80 assembly language. This section assumes you already have
some knowledge about Z80 machine language and the basic operations of the CP/M
system. If you need more information about Z80 or CP/M, your local bookstore w
probably has several good reference books about these widely covered subjects. To fully
cover these topics is beyond the scope of this reference guide. See "Suggestions for
Reading" at the end of this guide. I
Part I of this appendix first lists each CP/M BIOS, 8502 BIOS and User Function ^
routine by number. Part II explains how and provides examples to call these routines.
Part III lists the Z80 memory map. J
The format used to describe these routines are as follows: u
a) Function Name "j
b) Input Parameters I
c) Output Parameters
d) Brief Description
e) Other required preparatory/post routines (or additional information) j J
The 8502 BIOS and User Function routines require certain values to be placed into
the Z80 microprocessor registers. In Chapter 5 you learned about the 8502 microproces- rt
sor registers: A, X, Y, Status (PSW), Stack Pointer (S) and Program Counter (PC). The jj
Z80 also has applicable registers. The Z80 registers are named as follows:
A
BC
DE
HL
PSW
IX
IY
PC
SP
(Accumulator)
(Status Word)
(X register)
(Y index register)
(program counter)'
(stack pointer)
Certain registers can be used as a register pair, to represent a 16 bit address, or as C
single 8-bit register. The Z80 has a duplicate set of registers for interrupt processing. (
For more detailed information on the Z80 microprocessor consult the "Sugges
tions for Further Reading." For more detailed information on the CP/M system, refer to
the Commodore 128 System Guide to receive the full set of CP/M Plus documentation, \ j
written by Digital Research Inc., through Commodore. LJ