From 19c1afbe7975603534f9ce9cb3f0ac3966da8f19 Mon Sep 17 00:00:00 2001 From: Jonathan Gevaryahu Date: Thu, 14 Mar 2013 16:27:02 +0000 Subject: [PATCH] s14001a.c: Add note that the four dac test pins are really digital out pins [PlgDavid] --- src/emu/sound/s14001a.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/src/emu/sound/s14001a.c b/src/emu/sound/s14001a.c index 9164b7ddbb4..288de465175 100644 --- a/src/emu/sound/s14001a.c +++ b/src/emu/sound/s14001a.c @@ -53,13 +53,13 @@ labeling. _| |_ ROM CLOCK/CKR <- |_|4 37|_| <- ROM D6 _| |_ - ?DAC TEST? ?? |_|5 36|_| -> ROM A10 + DIGITAL OUT 0 <- |_|5 36|_| -> ROM A10 _| |_ - ?DAC TEST? ?? |_|6 35|_| -> ROM A9 + DIGITAL OUT 1 <- |_|6 35|_| -> ROM A9 _| |_ - ?DAC TEST? ?? |_|7 34|_| <- ROM D5 + DIGITAL OUT 2 <- |_|7 34|_| <- ROM D5 _| |_ - ?DAC TEST? ?? |_|8 33|_| -> ROM A8 + DIGITAL OUT 3 <- |_|8 33|_| -> ROM A8 _| |_ ROM /EN <- |_|9 32|_| <- ROM D4 _| S |_ @@ -102,6 +102,10 @@ which is normally impossible. The later 'version 3' TSI speech board as featured an advertisement in the John Cater book probably also has this feature, in addition to external speech rom banking. +The Digital out pins supply a copy of the 4-bit waveform which also goes to the +internal DAC. They are only valid every other clock cycle. It is possible that +on 'invalid' cycles they act as a 4 bit input to drive the dac. + Because it requires -10V to operate, the chip manufacturing process must be PMOS. /-----------\