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RG fixed a bug in the Vavasour emulator clock2 module. clock2 is now of type Sbrtn instead of Systm. clock.asm has been modified to link to this type.
author boisy
date Sat, 17 Jul 2004 12:20:31 +0000
parents 7af4d12008f4
children 27e85b681dab
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; m6809
;
; $Id$
;
; Edt/Rev  YYYY/MM/DD  Modified by
; Comment
; ------------------------------------------------------------------
;          2004/05/17  Boisy G. Pitre
; Started.

           .title  Motorola 6809 Definitions

; Motorola 6809 Register Definitions
R$CC     ==      0          ; Condition Codes register
R$A      ==      1          ; A Accumulator
R$B      ==      2          ; B Accumulator
R$D      ==      R$A        ; Combined A:B Accumulator
R$DP     ==      3          ; Direct Page register
R$X      ==      4          ; X Index register
R$Y      ==      6          ; Y Index register
R$U      ==      8          ; User Stack register
R$PC     ==      10         ; Program Counter register
R$Size   ==      12         ; Total register package size


; Condition Code Definitions
Entire   ==     0b10000000  ; Full Register Stack flag
FIRQMask ==     0b01000000  ; Fast-Interrupt Mask bit
HalfCrry ==     0b00100000  ; Half Carry flag
IRQMask  ==     0b00010000  ; Interrupt Mask bit
Negative ==     0b00001000  ; Negative flag
Zero     ==     0b00000100  ; Zero flag
TwosOvfl ==     0b00000010  ; Two's Comp Overflow flag
Carry    ==     0b00000001  ; Carry bit
IntMasks ==     IRQMask+FIRQMask
Sign     ==     0b10000000  ; sign bit