CpcAlive is a
programming
environment
Amstrad CPC
compatible
for graphics
 animations
creation.


operation
SmallAsm is a Z80 assembler
for Dos
Cpc basic key words
( English - Español )
Cpc basic error messages
The memory
The Cpc system vectors
Diskettes management
CpcAlive installer for Windows
and for DosBox
CpcAlive Documentation
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Amstrad Cpc Rom code sample with programmable basic instructions (Resident System eXtension)

.org 0C000h

                .db 1                   ; 0C000h     Rom type=BackGround Rom
              
                ; version 1.23
                .db 1                   ; 0C001h      Rom Mark Number
                .db 2                   ; 0C002h      Rom Version Number
                .db 3                   ; 0C003h      Rom Modif Level

                .dw MnemoTb    ; 0C004h    address table of the names which will be
                                           ;                    used to call the routines via the BASIC
                jp RomIni            ; 0C006h     first vector. This vector will be automatically
                                            ;                   called after each Cpc system initialization
                jp command1      ; 0C009h     second vector
                jp command2      ; 0C00Ch     ...

; names table
MnemoTb   .db "ROMIN"        ; |ROMINI   (execute the subrutine "RomIni")
                    .db 049h | 080h         ; "I" or 080h
                    .db "NAME"           ; |NAME1   (execute the subrutine "command1")
                    .db 031h | 080h         ; "1" or 080h
                    .db "NAME"           ; |NAME2   (execute the subrutine "command2")
                    .db 032h | 080h         ; "2" or 080h
                    .db 0                          ; 0=mark "end of table"
; remark:
; The end of each name is indicated by setting the bit 7 on the last letter.
; To call the command, it will be enough to type the name preceded by the sign "vertical bar | ", from the Cpc BASIC interpreter.

 RomIni:           push hl
                         ld hl,IniMes            ; message to be posted with starting (zero terminated)
                         call TxtPost
                         pop hl
                         scf                            ; carry = ok
                         ret

command1:       ld hl,Ok1Mes          ; message to be posted
                          call TxtPost
                          ret

command2:        ld hl,Ok2Mes          ; message to be posted
                           call TxtPost
                           ret

IniMes              .db " Program V1.23",10,13,0
Ok1Mes           .db "OK1",10,13,0
Ok2Mes           .db "OK2",10,13,0

; ** POST TEXT **
; <HL=offset first character of the zero terminated text
TxtPost:           ld a,(hl)
                          inc hl
                          or a                    ; end of message ?
                          ret z                   ; yes>return
                          call 0BB5Ah      ; system vector "Post character"
                          jr TxtPost

.end