Hi all:
I want to open this little thread to document an old achievement done by an Spanish technician on the late 90's, whose nick was Dr. Bacterio, sadly the source code can be considered almost lost as it was never released to the public.
As a fellow Amibay member developed his own variant from scratch (see here) It may be useful for further reference.
Here we go, the beast itself:
Next, in detail view of Ramsey pull ups and cut circuit tracks, Note the Ramsey pinns 45 46 are wired to two pullups an the to pin 47 (Ramsey A24 and A25 signals wired to A26) :
Back side, left wire is soldered directly to a track there that was not traced by us yet, right side wire is passed thru a via to underneath the GAL:
Thru via wire goes there on the GAL chip:
Detail of back side SIMM banks wire bridges and pull-up, if my notes are ok to pins 19 and 29 on the simm banks (must be signals A10 & A11 on the SIMMs):
More detailed view of this:
Final notes: This hack is somewhat restrictive in memory configurations as once done only two memory configurations are allowed and both fully autoconfig:
1) The traditional 2X8MB double sided SIMMs to get a total of 16MB (as any other A4000 can do by default).
2) The extended one using 4X16MB single sided SIMMs to get a total of 64MB.
Other configurations are forbidden.
Finally I want to thank two fellow members here than were lately trying to figure out and document more things about this old hack but due to lack of time nothing more was done:
Debvgger (who is also the author of the Pics, used with permission) and Crumb who along me tried to give some more light and unveil a bit more about this epic old achievement.
Hope you'll find it useful.
I want to open this little thread to document an old achievement done by an Spanish technician on the late 90's, whose nick was Dr. Bacterio, sadly the source code can be considered almost lost as it was never released to the public.
As a fellow Amibay member developed his own variant from scratch (see here) It may be useful for further reference.
Here we go, the beast itself:
Next, in detail view of Ramsey pull ups and cut circuit tracks, Note the Ramsey pinns 45 46 are wired to two pullups an the to pin 47 (Ramsey A24 and A25 signals wired to A26) :
Back side, left wire is soldered directly to a track there that was not traced by us yet, right side wire is passed thru a via to underneath the GAL:
Thru via wire goes there on the GAL chip:
Detail of back side SIMM banks wire bridges and pull-up, if my notes are ok to pins 19 and 29 on the simm banks (must be signals A10 & A11 on the SIMMs):
More detailed view of this:
Final notes: This hack is somewhat restrictive in memory configurations as once done only two memory configurations are allowed and both fully autoconfig:
1) The traditional 2X8MB double sided SIMMs to get a total of 16MB (as any other A4000 can do by default).
2) The extended one using 4X16MB single sided SIMMs to get a total of 64MB.
Other configurations are forbidden.
Finally I want to thank two fellow members here than were lately trying to figure out and document more things about this old hack but due to lack of time nothing more was done:
Debvgger (who is also the author of the Pics, used with permission) and Crumb who along me tried to give some more light and unveil a bit more about this epic old achievement.
Hope you'll find it useful.
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