CpcAlive is a
Amstrad CPC

for graphics


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


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

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

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

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