Mercurial > hg > Members > kono > nitros9-code

changeset 2929:8629f64b7dd3

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
rominfo: Disable autostart interrupt signal from ROMPak For autostarting ROM cartridges the expansion port CART input is taken to CB1 on PIA1 in order to trigger FIRQ. If we don't disable this input on the PIA we will get FIRQ's all the time. Bit 0 of CRB (control register B) defines whether the CB1 input will trigger IRQB MPU interrupt on the PIA. (IRQA and IRQB are connected to FIRQ on the 6809)
author Tormod Volden <debian.tormod@gmail.com>
date Sat, 18 Jan 2014 21:44:44 +0100
parents 4ec45bc24278
children e93ace49362e
files level1/modules/rominfo.asm
diffstat 1 files changed, 4 insertions(+), 0 deletions(-) [+]
line wrap: on
line diff
--- a/level1/modules/rominfo.asm	Sat Jan 18 10:12:28 2014 +0100
+++ b/level1/modules/rominfo.asm	Sat Jan 18 21:44:44 2014 +0100
@@ -147,7 +147,11 @@
          clr   -2,x
          bitb  2,x
 
+         IFNE  ROMPak
+         lda   #$36                    inhibit ROMPak autostart FIRQ
+         ELSE
          lda   #$37
+         ENDC
          sta   PIA1Base+3
 
          lda   PIA0Base+3