Hardware Reference
In-Depth Information
Figure 12.7
Internal arrangement of the Analogue Devices AD7569 8-bit
analogue I/O system
Software
The software for the speech enunciator can usefully take advantage of the mixed
language interface which is provided within the Microsoft suite of programming
languages. Time critical routines (such as those which drive the ADC and DAC)
can be written in assembly language while those which deal with disk filing and
screen displays can be quickly and easily developed in QuickBASIC.
The assembly language module shown below is responsible for the recoding
and playback process. These routines are liberally commented and should thus
be reasonably self-explanatory (Chapter 5 provides more details of assembly
language programming).
.MODEL
MEDIUM
.STACK
100H
.CODE
; This routine records data from the ADC in a
; 128k byte buffer - starting at 70000H
; Registers used: AX,BX,CX,CX,DX,DI,DS
; Parameters passed: 16-bit delay in stack frame
; Parameter returned: none
PUBLIC Rec
Rec PROC
PUSH BP
; save old base pointer
MOV
BP,SP
; set stack frame pointer
