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Z80: In INTACK cycle, force 0xFF onto the databus

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This commit is contained in:
David Banks 2018-09-30 12:29:08 +01:00
parent cbebb0e11d
commit 6fcb3077eb
1 changed files with 8 additions and 1 deletions
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9
chip-z80/support.js
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@ -110,7 +110,14 @@ var state = 0;
var last_rd_done = 1;
function handleBusRead(){
if(!isNodeHigh(nodenames['_rd'])){
if(!isNodeHigh(nodenames['_m1']) && !isNodeHigh(nodenames['_iorq'])) {
// Interrupt acknownledge cycle, force 0xFF onto the bus
// In IM0 this is seen as RST 0x38
// In IM1 this is ignored
// In IM2 this is used as the low byte of the vector
// TODO: ideally this "vector" would be a configurable parameter
writeDataBus(0xff);
} else if(!isNodeHigh(nodenames['_rd'])){
var a = readAddressBus();
var d = eval(readTriggers[a]);
if(d == undefined)