--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/os9/level2/clock.asm	Mon Jul 23 16:07:12 2018 +0900
@@ -0,0 +1,117 @@
+********************************************************************
+* Clock - OS-9 Level One V2 Clock module
+*
+* $Id: clock.asm,v 1.1.1.1 2001/02/21 23:30:52 boisy Exp $
+*
+* NOTE:  This clock is TOTALLY VALID for ALL DATES between 1900-2155
+*
+* Ed.    Comments                                       Who YY/MM/DD
+* ------------------------------------------------------------------
+* 5      Tandy/Microware original version
+* 6      Modified to handle leap years properly for     BGP 99/05/03
+*        1900 and 2100 A.D.
+
+         nam   Clock
+         ttl   OS-9 Level One V2 Clock module
+
+         ifp1
+         use   defsfile
+         endc
+
+usefirq  equ 0
+
+tylg     set   Systm+Objct
+atrv     set   ReEnt+rev
+rev      set   $01
+edition  set   $06
+TimerPort set  $ffb0
+
+         mod   eom,name,tylg,atrv,ClkEnt,size
+
+size     equ   .
+
+name     fcs   /Clock/
+         fcb   edition
+
+SysTbl   fcb   F$Time
+         fdb   FTime-*-2
+         fcb   F$STime
+         fdb   FSTime-*-2
+         fcb   $80
+
+
+       ifeq  usefirq-1
+ClockFIRQ 
+         leas  -1,s
+         pshs  d,dp,x,y
+         lda   8,s
+         ora   #$80       Entire flag
+         pshs  a
+         stu   8,s
+         jmp   [$FFF8]
+       endc
+ClockIRQ 
+         ldx   #TimerPort
+         lda   ,x
+         bita  #$10
+         beq   L00AE
+L00AE    leax  ClockIRQ1,pcr
+         stx   <D.SvcIRQ
+         jmp   [D.XIRQ]   Chain through Kernel to continue IRQ handling
+ClockIRQ1
+         inc   <D.Sec     go up one second
+         lda   <D.Sec     grab current second
+         cmpa  #60        End of minute?
+         blo   VIRQend    No, skip time update and alarm check
+         clr   <D.Sec     Reset second count to zero
+VIRQend
+         ldx   #TimerPort
+         lda   #$8f
+         sta   >TimerPort
+         jmp   [>D.Clock]
+
+TkPerTS  equ   2
+
+ClkEnt   equ   *
+         pshs  cc
+         orcc  #FIRQMask+IRQMask       mask ints
+         leax  >ClockIRQ,pcr
+         stx   <D.IRQ
+       ifeq usefirq-1
+         leax  >ClockFIRQ,pcr
+         stx   $FFF6     must be a RAM
+       endc
+* install system calls
+         leay  >SysTbl,pcr
+         os9   F$SSvc
+         ldd   #59*256+TkPerTS last second and time slice in minute
+         std   <D.Sec     Will prompt RTC read at next time slice
+         stb   <D.TSlice  set ticks per time slice
+         stb   <D.Slice   set first time slice
+         lda   #TkPerSec  Reset to start of second
+         sta   <D.Tick
+
+         ldx   #TimerPort
+         ldb   #$8f     start timer
+         stb   ,x
+         puls  pc,cc
+
+* F$Time system call code
+FTime    ldx   #TimerPort
+         ldb   #$04
+         stb   ,x
+         leax  1,x        Address of system time packet
+RetTime  ldy   <D.Proc    Get pointer to current proc descriptor
+         ldb   P$Task,y   Process Task number
+         lda   <D.SysTsk  From System Task
+         ldu   R$X,u
+STime.Mv ldy   #6         Move 6 bytes
+FMove    os9   F$Move
+         rts
+
+FSTime   clrb
+         rts
+
+         emod
+eom      equ   *
+         end