Page 2 of 2
Posted: Sat Feb 14, 2009 10:42 am
by tokumaru
coinheaven wrote:do any of the prg or chr pins have to be lifted?
Only the higher address lines I guess, because there is no place for them in board anyway... But it may depend on the kind of chip you are using.
Are you sure you connected everything correctly? Can you post pictures of what you did?
Posted: Sun Feb 15, 2009 2:28 pm
by coinheaven
i was using 2 27c512 chips, so all the pins fit on the board. ill look over it again and put up some pics
Posted: Sun Feb 15, 2009 3:19 pm
by hybrid
its an open bus error preventing the rom from working thanks to Cah4e3
for fixing it.
http://www.geocities.com/hybrid012000/freefall.zip
Posted: Sun Feb 15, 2009 11:01 pm
by marvelus10
I see this kind of went off topic,
Coinheaven what are you trying to reproduce now with this new found information.
Posted: Mon Feb 16, 2009 5:06 pm
by coinheaven
ok, here is what i did:
on 74161 chip:
bent up pins 3,4,5,6,11,12,13,14
then:
connect pin 11 (PRG) to pin 3 (74161)
connect pin 1 (PRG) to pin 14 (161)
connect pin 16 (PRG) to pin 4 (161)
connect pin 17 (PRG) to pin 5 (161)
connect pin 18 (PRG) to pin 6 (161)
connect pin 26 (CHR) to pin 13 (161)
connect pin 27 (CHR) to pin 12 (161)
connect pin 1 (CHR) to pin 11 (161)
is this correct?
Posted: Mon Feb 16, 2009 5:59 pm
by tokumaru
That should work...
Posted: Mon Feb 16, 2009 6:35 pm
by coinheaven
nope didnt work. i think the pin 1 of the CHR and PRG needs to be lifted as does pin 26 and 27 because they are address lines. does that sound right?
Posted: Mon Feb 16, 2009 8:21 pm
by tokumaru
coinheaven wrote:nope didnt work. i think the pin 1 of the CHR and PRG needs to be lifted as does pin 26 and 27 because they are address lines. does that sound right?
Yeah, I assumed they were! The address lines from the ROMs that are connected to the 74161 must be connected
only to the 74161.
Posted: Tue Feb 17, 2009 2:15 am
by coinheaven
ok, ill bend them up and let you know if it works