Intel MCS 51 - Page 321

intel.
83C152 HARDWARE DESCRIPTION
mode_logic (n) :
if (DCONnindicates
if (DCONnindicates
{
if (demand-flag
else return O;
)
if (DCONnindicates
(
if (SARII= SBUF
if (DARn= SBUF
burst-mode) return 1;
extern_demand-mode)
= 1) return 1;
SP-demand.mode)
.AND. RI
= 1) return
.AND. TI
= 1) return
1;
1;
if (sARn = RFIFO .AND. RFNE= 1) return 1;
if (DARII=TFIFO .AND. TFNF=l .AND.
previous-cycle = instruction_cycle) return 1;
else return O;
)
if (DCONnindicates alt-cycles_mode)
{
if (DCONmindicates .NOT. alt-cycles-mode
.OR.
GOm = O)
{
if (previous_cycle = instruction_cycle’
return 1;
else return O;
1
if (previous-cycle
= instruction-cycle
.AND. previousdma-cycle = .NOZ. DNAII)
return 1;
1
return O;
end mode-logic(n) ;
Figure4.13.DMAModeLogic
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