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author Lord-Nightmare <Lord-Nightmare@users.noreply.github.com>2016-09-26 01:29:09 -0400
committer Lord-Nightmare <Lord-Nightmare@users.noreply.github.com>2016-09-26 01:29:44 -0400
commit2639397a9c018913e37956b240408817558ac6a1 (patch)
treee81b4317377b7bff9388331d384ff5caf652cc57
parent85410f9a246f0da3b32d3af0751bd12c3ed13da6 (diff)
fix incomplete info (n/w)
-rw-r--r--src/mame/drivers/superqix.cpp11
1 files changed, 7 insertions, 4 deletions
diff --git a/src/mame/drivers/superqix.cpp b/src/mame/drivers/superqix.cpp
index 52e0ca43819..bc5f6525b3b 100644
--- a/src/mame/drivers/superqix.cpp
+++ b/src/mame/drivers/superqix.cpp
@@ -68,10 +68,13 @@ Super Qix:
The V1.1, V1.2 and US PCBS have two resistors from VCC to GND forming a
voltage divider on top of 7H, the resistor from VCC/Pin 14 to Common is
- 22KOhms, the other resistor is unknown and seems to connect to GND/Pin 7.
- The center of the two resistors connects to one end of a 0.1uf capacitor,
- the other end of the capacitor connects to 7H pin 12.
- This implies some sort of brief/reset pulse generation or filter on pin 12.
+ 22KOhms, the other resistor is also 22KOhms and seems to connect to
+ GND/Pin 7. The center of the two resistors connects to one end of a 0.1uf
+ capacitor and also to 7H pin 4, the other end of the capacitor connects to
+ 7H pin 12.
+ This implies some sort of brief/reset pulse generation or filter on pin 12,
+ or more likely some abuse of the TTL input hysteresis of the 74LS86 IC itself
+ such that transitions of pin 12 cause transitions on pin 4 as well, or similar.
Again, what exactly this accomplishes is unclear without further tracing.
- sqixb2 is a bootleg of sqixb1, with the MCU removed.