; CATIIMRT.mu Diablo Port Audio Terminal MRT for Alto II
; Last modified by L. Stewart December 29, 1979 8:47 PM
; to include call to AudioTest. Mouse code returns to TX0,
; added TASK to mouse code

; CPDispMRT.mu -- MRT modified to run on CommProc-based Alto Gateway
;and to accompany rewritten display microcode (GateDisplay.mu)

; **** Memory Refresh task ****
; This is the MRT for Alto IIs with Extended Memory (16K chips).
; It is modified to abolish the Interval Timer and eliminate CLOCKTEMP, and
; do away with cursor processing (now done by the cursor task itself).
; (Actually, there is nothing about this MRT that has anything directly to
; do with the CommProc, but it is named CPMRT to distinguish it from
; EIAMRT, which is specialized to the EIA board.)

!17,20,TX0,TX6,TX3,TX2,TX8,TX5,TX1,TX7,TX4,,,,,,,;

!1,2,NOCLK,CLOCK;

$MTEMP$R25;
$R37$R37;
$REFIIMSK$7777;

; This version assumes MRTACT is cleared by BLOCK, not MAR← R37
; R37 [4-13] are the low bits of the TOD clock
; R37 [8-14] are the refresh address bits
; Each time MRT runs, four refresh addresses are generated, though
; R37 is incremented only once. Sprinkled throughout the execution
; of this code are the following operations having to do with refresh:
;MAR← R37
;R37← R37 +4NOTE THAT R37 [14] DOES NOT CHANGE
;MAR← R37 XOR 2TOGGLES BIT 14
;MAR← R37 XOR 200TOGGLES BIT 8
;MAR← R37 XOR 202TOGGLES BITS 8 AND 14

MRT:MAR← R37;**FIRST REFRESH CYCLE**
SINK← MOUSE, BUS;MOUSE DATA IS ANDED WITH 17B
MRTA:L← T← -2, :TX0;DISPATCH ON MOUSE CHANGE
TX0:NOP, :AudioTest;Call Audio code.
ATDone:T← R37;INCREMENT CLOCK
T← 3+T+1;IE. T← T +4.
L← REFIIMSK AND T;ZERO HIGH 4 BITS
R37← L; STORE UPDATED CLOCK
T← 2;NO STATE AT THIS POINT IN PUBLIC REGS
MAR← R37 XOR T,T← R37;**SECOND REFRESH CYCLE**
L← REFZERO AND T;ONLY THE CLOKCK BITS, PLEASE
SH=0, TASK;TEST FOR CLOCK OVERFLOW
:NOCLK;[NOCLK,CLOCK]
NOCLK:T ← 200;
MAR← R37 XOR T;**THIRD FEFRESH CYCLE**
T← 2 OR T, BLOCK;CLEARS WAKEUP REQUEST FF
MAR← R37 XOR T;**FOURTH REFRESH CYCLE**
TASK;
:MRT;END OF MAIN LOOP
; Memory Refresh Task (cont’d)

CLOCK:MAR← CLOCKLOC;R37 OVERFLOWED.
NOP;
L← MD+1;INCREMENT CLOCK IM MEMORY
MAR← CLOCKLOC;
MTEMP← L, TASK;
MD← MTEMP, :NOCLK;

;AFTER THIS DISPATCH, T WILL CONTAIN XCHANGE, L WILL CONTAIN YCHANGE-1

TX1:L← T← ONE +T, :M00;Y=0, X=1
TX2:L← T← ALLONES, :M00;Y=0, X=-1
TX3:L← T← 0, :M00;Y=1, X=0
TX4:L← T← ONE AND T, :M00;Y=1, X=1
TX5:L← T← ALLONES XOR T, :M00;Y=1, X=-1
TX6:T← 0, :M00;Y=-1, X=0
TX7:T← ONE, :M00;Y=-1, X=1
TX8:T← ALLONES, :M00;Y=-1, X=-1

M00:MAR← MOUSELOC;START THE FETCH OF THE COORDINATES
MTEMP← L;YCHANGE -1
L← MD+ T;X+ XCHANGE
T← MD;Y
T← MTEMP+ T+1;Y+ (YCHANGE-1) + 1
MTEMP← L, L← T;
T← R37;Save R37 for use as temp
MAR← MOUSELOC;NOW RESTORE THE UPDATED COORDINATES
R37← L, L← T;
MD← MTEMP;
MD← R37, TASK;
R37← L, :TX0;Restore R37