1 files changed, 20 insertions, 2 deletions

diff --git a/isa/decode.cpp b/isa/decode.cpp
index 9563327..c35118b 100644
--- a/isa/decode.cpp
+++ b/isa/decode.cpp
@@ -152,6 +152,24 @@ instruction_context decode(unsigned int dfifb, unsigned int pc, unsigned int bit
                                     ctx.next_pc = (ctx.next_pc & ~07777) | ((ctx.next_pc + 1) & 07777);
                             };
                             break;
+                        case 5:
+                            // KIE set TT_INPUT_INT_ENABLE to the low bit of the accumulator
+                            inst.need_read_acc = true;
+                            inst.write_ctlreg = TT_INPUT_INT_ENABLE;
+                            inst.ef = [](auto &ctx) {
+                                ctx.ctlval = ctx.acc.value() & 3;
+                            };
+                            break;
+                        case 6:
+                            // KRB transfer keyboard buffer to accumulator and clear TTI flag
+                            inst.read_ctlreg = TT_BITS;
+                            inst.need_write_acc = true;
+                            inst.write_ctlreg = TT_BITS;
+                            inst.ef = [](auto &ctx) {
+                                ctx.acc = (ctx.ctlval.value() & TTI_DATA) >> TTI_DATA_SHIFT;
+                                ctx.ctlval.value() &= ~TTI_FLAG;
+                            };
+                            break;
                         default:
                             inst.ef = [bits](auto &ctx) {
                                 std::cerr << "unimplemented IOT KB suboperation " << (bits & 07) << "\n";
@@ -194,7 +212,7 @@ instruction_context decode(unsigned int dfifb, unsigned int pc, unsigned int bit
                             inst.write_ctlreg = TT_BITS;
                             inst.ef = [](auto &ctx) {
                                 auto &x = ctx.ctlval.value();
-                                auto chr = ctx.acc.value() ^ 0x80;
+                                auto chr = ctx.acc.value();
                                 x &= ~TTO_DATA;
                                 x |= (chr << TTO_DATA_SHIFT) & TTO_DATA;
                                 x |= TTO_TX;
@@ -216,7 +234,7 @@ instruction_context decode(unsigned int dfifb, unsigned int pc, unsigned int bit
                             inst.write_ctlreg = TT_BITS;
                             inst.ef = [](auto &ctx) {
                                 auto &x = ctx.ctlval.value();
-                                auto chr = ctx.acc.value() ^ 0x80;
+                                auto chr = ctx.acc.value();
                                 x &= ~TTO_FLAG & ~TTO_FLAG_OLD & ~TTO_DATA;
                                 x |= (chr << TTO_DATA_SHIFT) & TTO_DATA;
                                 x |= TTO_TX;