diff options
author | Lord-Nightmare <Lord-Nightmare@users.noreply.github.com> | 2016-09-26 01:29:09 -0400 |
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committer | Lord-Nightmare <Lord-Nightmare@users.noreply.github.com> | 2016-09-26 01:29:44 -0400 |
commit | 2639397a9c018913e37956b240408817558ac6a1 (patch) | |
tree | e81b4317377b7bff9388331d384ff5caf652cc57 | |
parent | 85410f9a246f0da3b32d3af0751bd12c3ed13da6 (diff) |
fix incomplete info (n/w)
-rw-r--r-- | src/mame/drivers/superqix.cpp | 11 |
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. |