Another midway 8080 and pod (space invaders deluxe) question
Have a space invaders deluxe board. Rom tests based on quarterarcade fluke crc's are fine on loop. Game does not run correctly. Ram short fails all over the place. So trying to narrow it down a touch I do a write 0x2000 = 0xff then a read 0x2000. Comes back with 0xFF. Hit loop and it starts to wander all over creation. Thinking I have a bad bit I do some testing. Write 0x01, read & loop is stable=0x01. Same with 0x02, 04, 08, 10, 20, etc etc. In fact everything I tried came back with a good read loop EXCEPT 0xFF. With that value I get random garbage. WTF????? Any ideas on why ram would fail this way? Thanks, David _______________________________________________ Techtoolslist mailing list Techtoolslist@flippers.com http://seven.pairlist.net/mailman/listinfo/techtoolslist FTP site is: ftp://ttl.arcadetech.org/TTL/Test_Equipment Archive site: http://seven.pairlist.net/pipermail/techtoolslist/
On 06/28/2014 11:54 PM, David Shoemaker wrote:
Have a space invaders deluxe board.
Rom tests based on quarterarcade fluke crc's are fine on loop. Game does not run correctly.
Ram short fails all over the place.
So trying to narrow it down a touch I do a write 0x2000 = 0xff then a read 0x2000.
Comes back with 0xFF. Hit loop and it starts to wander all over creation.
Thinking I have a bad bit I do some testing.
Write 0x01, read & loop is stable=0x01.
Same with 0x02, 04, 08, 10, 20, etc etc. In fact everything I tried came back with a good read loop EXCEPT 0xFF. With that value I get random garbage.
WTF?????
Any ideas on why ram would fail this way?
Thanks,
David
Hi David, How about the 'ol AA/55h test? This is similar to my problem with my 8080 pod having trouble resolving FF on a number of ROM locations - read them as other characters - alternating. Do you get the same read value if you loop the read (typo fixed for clarity) for that memory address? John :-#)# -- How to subscribe or unsubscribe from TTL http://seven.pairlist.net/mailman/listinfo/techtoolslist _______________________________________________ Techtoolslist mailing list Techtoolslist@flippers.com http://seven.pairlist.net/mailman/listinfo/techtoolslist FTP site is: ftp://ttl.arcadetech.org/TTL/Test_Equipment Archive site: http://seven.pairlist.net/pipermail/techtoolslist/
Comes back with 0xFF. Hit loop and it starts to wander all over creation.
From highest to lower probability, based on my experience. YMMV:
1) bus fight with ROM or I/O bus 2) bus transceiver(s) bad 3) genuine RAM problem 4) I/O control latch problem 5) incorrect clock phasing or enable signal threshold between the even and odd RAM banks 6) other
Any ideas on why ram would fail this way?
They reportedly could suffer physical damage if the -5V (or was it the +12V) was not properly supplied. Not sure the exact failure mechanism was at the die level. Alex ---- ayeckley@elektronforge.com www.elektronforge.com _______________________________________________ Techtoolslist mailing list Techtoolslist@flippers.com http://seven.pairlist.net/mailman/listinfo/techtoolslist FTP site is: ftp://ttl.arcadetech.org/TTL/Test_Equipment Archive site: http://seven.pairlist.net/pipermail/techtoolslist/
Maybe a sync problem (video system butting heads with processor---wouldn't happen in normal use). On Jun 30, 2014 2:12 PM, "Alex Yeckley" <ayeckley@sierralobo.com> wrote:
Comes back with 0xFF. Hit loop and it starts to wander all over creation.
From highest to lower probability, based on my experience. YMMV:
1) bus fight with ROM or I/O bus 2) bus transceiver(s) bad 3) genuine RAM problem 4) I/O control latch problem 5) incorrect clock phasing or enable signal threshold between the even and odd RAM banks 6) other
Any ideas on why ram would fail this way?
They reportedly could suffer physical damage if the -5V (or was it the +12V) was not properly supplied. Not sure the exact failure mechanism was at the die level.
Alex ---- ayeckley@elektronforge.com www.elektronforge.com
_______________________________________________ Techtoolslist mailing list Techtoolslist@flippers.com http://seven.pairlist.net/mailman/listinfo/techtoolslist FTP site is: ftp://ttl.arcadetech.org/TTL/Test_Equipment Archive site: http://seven.pairlist.net/pipermail/techtoolslist/
_______________________________________________ Techtoolslist mailing list Techtoolslist@flippers.com http://seven.pairlist.net/mailman/listinfo/techtoolslist FTP site is: ftp://ttl.arcadetech.org/TTL/Test_Equipment Archive site: http://seven.pairlist.net/pipermail/techtoolslist/
I had this same problem on an Atari Hercules/Superman Board, I could read/write the ram, but when I did a loop random reads would fly across the screen., turned out to be a clocking issue ( I posted the repair on KLOV and VillageBBS ) I don't think midway 8080 boards use different speed clocks between ram and rom read/writes -----Original Message----- From: Techtoolslist [mailto:techtoolslist-bounces@flippers.com] On Behalf Of Rodger Boots Sent: Monday, June 30, 2014 9:45 PM To: ayeckley@sierralobo.com; Technical Tools Mail List Subject: Re: [Techtoolslist] Another midway 8080 and pod (space invaders deluxe) question Maybe a sync problem (video system butting heads with processor---wouldn't happen in normal use). On Jun 30, 2014 2:12 PM, "Alex Yeckley" <ayeckley@sierralobo.com> wrote:
Comes back with 0xFF. Hit loop and it starts to wander all over creation.
From highest to lower probability, based on my experience. YMMV:
1) bus fight with ROM or I/O bus 2) bus transceiver(s) bad 3) genuine RAM problem 4) I/O control latch problem 5) incorrect clock phasing or enable signal threshold between the even and odd RAM banks 6) other
Any ideas on why ram would fail this way?
They reportedly could suffer physical damage if the -5V (or was it the +12V) was not properly supplied. Not sure the exact failure mechanism was at the die level.
Alex ---- ayeckley@elektronforge.com www.elektronforge.com
_______________________________________________ Techtoolslist mailing list Techtoolslist@flippers.com http://seven.pairlist.net/mailman/listinfo/techtoolslist FTP site is: ftp://ttl.arcadetech.org/TTL/Test_Equipment Archive site: http://seven.pairlist.net/pipermail/techtoolslist/
_______________________________________________ Techtoolslist mailing list Techtoolslist@flippers.com http://seven.pairlist.net/mailman/listinfo/techtoolslist FTP site is: ftp://ttl.arcadetech.org/TTL/Test_Equipment Archive site: http://seven.pairlist.net/pipermail/techtoolslist/ _______________________________________________ Techtoolslist mailing list Techtoolslist@flippers.com http://seven.pairlist.net/mailman/listinfo/techtoolslist FTP site is: ftp://ttl.arcadetech.org/TTL/Test_Equipment Archive site: http://seven.pairlist.net/pipermail/techtoolslist/
On 06/30/2014 7:00 PM, William Stillwell wrote:
I had this same problem on an Atari Hercules/Superman Board, I could read/write the ram, but when I did a loop random reads would fly across the screen., turned out to be a clocking issue ( I posted the repair on KLOV and VillageBBS )
I don't think midway 8080 boards use different speed clocks between ram and rom read/writes
Hi William, Do you mind posting a short copy of your Atari Superman/Hercules solution here so it can be found in a search? Thanks, John :-#)#
-----Original Message----- From: Techtoolslist [mailto:techtoolslist-bounces@flippers.com] On Behalf Of Rodger Boots Sent: Monday, June 30, 2014 9:45 PM To: ayeckley@sierralobo.com; Technical Tools Mail List Subject: Re: [Techtoolslist] Another midway 8080 and pod (space invaders deluxe) question
Maybe a sync problem (video system butting heads with processor---wouldn't happen in normal use). On Jun 30, 2014 2:12 PM, "Alex Yeckley" <ayeckley@sierralobo.com> wrote:
Comes back with 0xFF. Hit loop and it starts to wander all over creation.
From highest to lower probability, based on my experience. YMMV:
1) bus fight with ROM or I/O bus 2) bus transceiver(s) bad 3) genuine RAM problem 4) I/O control latch problem 5) incorrect clock phasing or enable signal threshold between the even and odd RAM banks 6) other
Any ideas on why ram would fail this way? They reportedly could suffer physical damage if the -5V (or was it the +12V) was not properly supplied. Not sure the exact failure mechanism was at the die level.
Alex ---- ayeckley@elektronforge.com www.elektronforge.com
-- How to subscribe or unsubscribe from TTL http://seven.pairlist.net/mailman/listinfo/techtoolslist _______________________________________________ Techtoolslist mailing list Techtoolslist@flippers.com http://seven.pairlist.net/mailman/listinfo/techtoolslist FTP site is: ftp://ttl.arcadetech.org/TTL/Test_Equipment Archive site: http://seven.pairlist.net/pipermail/techtoolslist/
Posted... Hopefully it goes thru, it had pictures in it. Link is here: http://www.villagebbs.com/forum/index.php/topic,24850.msg205478.html#msg2054 78 -----Original Message----- From: Techtoolslist [mailto:techtoolslist-bounces@flippers.com] On Behalf Of John Robertson Sent: Tuesday, July 01, 2014 2:33 AM To: Technical Tools Mail List Subject: Re: [Techtoolslist] Another midway 8080 and pod (space invaders deluxe) question On 06/30/2014 7:00 PM, William Stillwell wrote:
I had this same problem on an Atari Hercules/Superman Board, I could read/write the ram, but when I did a loop random reads would fly across the screen., turned out to be a clocking issue ( I posted the repair on KLOV and VillageBBS )
I don't think midway 8080 boards use different speed clocks between ram and rom read/writes
Hi William, Do you mind posting a short copy of your Atari Superman/Hercules solution here so it can be found in a search? Thanks, John :-#)#
-----Original Message----- From: Techtoolslist [mailto:techtoolslist-bounces@flippers.com] On Behalf
Of
Rodger Boots Sent: Monday, June 30, 2014 9:45 PM To: ayeckley@sierralobo.com; Technical Tools Mail List Subject: Re: [Techtoolslist] Another midway 8080 and pod (space invaders deluxe) question
Maybe a sync problem (video system butting heads with processor---wouldn't happen in normal use). On Jun 30, 2014 2:12 PM, "Alex Yeckley" <ayeckley@sierralobo.com> wrote:
Comes back with 0xFF. Hit loop and it starts to wander all over creation.
From highest to lower probability, based on my experience. YMMV:
1) bus fight with ROM or I/O bus 2) bus transceiver(s) bad 3) genuine RAM problem 4) I/O control latch problem 5) incorrect clock phasing or enable signal threshold between the even and odd RAM banks 6) other
Any ideas on why ram would fail this way? They reportedly could suffer physical damage if the -5V (or was it the +12V) was not properly supplied. Not sure the exact failure mechanism was at the die level.
Alex ---- ayeckley@elektronforge.com www.elektronforge.com
-- How to subscribe or unsubscribe from TTL http://seven.pairlist.net/mailman/listinfo/techtoolslist _______________________________________________ Techtoolslist mailing list Techtoolslist@flippers.com http://seven.pairlist.net/mailman/listinfo/techtoolslist FTP site is: ftp://ttl.arcadetech.org/TTL/Test_Equipment Archive site: http://seven.pairlist.net/pipermail/techtoolslist/
participants (5)
-
Alex Yeckley -
David Shoemaker -
John Robertson -
Rodger Boots -
William Stillwell