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author | 2019-10-18 12:48:02 -0400 | |
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committer | 2019-10-18 12:49:18 -0400 | |
commit | ee76056937b75f981cd8f1a9bc467e2392dd18ab (patch) | |
tree | fc28266cfebba7eb1394abbfb029876416e6547b | |
parent | 697dfa9fac769726c136c9c487bb3d47b7d07f56 (diff) |
adc0804: Further note (nw)
-rw-r--r-- | src/devices/machine/adc0804.cpp | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/src/devices/machine/adc0804.cpp b/src/devices/machine/adc0804.cpp index ad39b1d8e81..aad5b88ffb3 100644 --- a/src/devices/machine/adc0804.cpp +++ b/src/devices/machine/adc0804.cpp @@ -26,6 +26,13 @@ multiple other devices are also clocked through pin 19, which yields the output of the internal Schmitt trigger clock circuit. + The ADC0804's INTR semaphore output reflects not the actual busy + state of the converter (as EOC does on the ADC0808) but an + internal flip-flop attached to it. This flip-flop is reset by + pulling either RD or WR active low; therefore, INTR will never + toggle if RD is tied to GND to keep the data outputs continuously + active. + **********************************************************************/ #include "emu.h" |