[Techtoolslist] Fluke 9010 and Gorf / Wizard of War etc.

[William Stillwell]

Most of the time Memory Protection is just there to protect the memory on
power up/down for saving High Scores, sounds like they added some control
logic to enable/disable writing to memory instead of using a voltage check.

William Stillwell ~ Hammy



On Mon, Mar 28, 2022 at 1:54 AM <davids at oz.net> wrote:

> So I dug into the schematic some more. And I realized that the
> 0xD000-0xD080
> range isn't 1 entire 2114 range.  And proved it by removing the X21 ram and
> trying the fluke writing to D100 which gives an error.
>
> This is controlled through the U1 (NOR) -> U8 (OR) pair.  And U1 is fed by
> the U9 latch and the U8 or gate by way of X33 jumper block.
>
> I pulled the x33 jumper block and was able to test the ram from D000-Dfff
> with the fluke.  So X33 removal disables the memory protection.
>
> Put in a dip switch in place of the hardwire jumper pack and verified that
> turning off switch 7 did the same.  This is the connection from pin's 7 and
> 10.
>
> So there you go a way to work around the "memory protection" feature of
> these boards for testing.  This also should mean that the watch dog can
> just
> be ignored in the fluke settings instead of having to pull the Q10
> transistor.
>
> I haven't tried the game operation without this jumper block in place but I
> don't know what it is actually doing in the first place.
>
> Looking at the way this latch does work after EVERY write to the protected
> memory resets the latch, so before every write to protected memory you have
> to disable the protection.  This is not something the fluke will be able to
> do as part of memory testing.  But pulling the jumper block for testing and
> reinstalling after should be fine.
>
> David
>
> -----Original Message-----
> From: Techtoolslist <techtoolslist-bounces at flippers.com> On Behalf Of John
> Robertson via Techtoolslist
> Sent: Sunday, March 27, 2022 7:20 PM
> To: techtoolslist at flippers.com
> Cc: John Robertson <jrr at flippers.com>
> Subject: Re: [Techtoolslist] Fluke 9010 and Gorf / Wizard of War etc.
>
> On 2022/03/26 10:07 p.m., davids at oz.net wrote:
> > Working on a stack of these boards.  There is no watch dog disable but
> > it is an easy enough thing to do by removing Q10 (the WD then can't
> toggle
> reset).
> >
> >
> >
> > With the Fluke connected
> >
> > I can run UUT and game will run fine
> >
> > I can test the Video Dram from 0x4000-0x7FFF no problem.
> >
> > I can test the cpu SRam from 0xD080-0xDFFF no problem.
> >
> >
> >
> > The cpu SRam from 0xD000-0xD07F though give a data error when trying
> > to write to it.
> >
> >
> >
> > >From the mame memory map it shows that ram 0xD000-0xD03F is
> > >protected_ram (I
> > think this is a typo because it is blocked for me to 7F).
> >
> >
> >
> > Looking though the tech tools list history I saw mention from Kev in
> > 2004 that there is a section of the ram that has a latch attached to
> > reset.  I think that is the protected ram mentioned in the memory map.
> >
> >
> >
> > The map also says address 0xA55B controls the protection.
> >
> >
> >
> > Looking at the gorf schematic page 63 (the rom/ram board) I can see
> > the latch Kev mentioned.
> >
> >
> >
> > U9:11 (74LS74) controls the chip select for X21 / X22.  And this is
> > tied to reset so would clear if the WD were to kick (but I have
> > disabled it)
> >
> >
> >
> > This is in turn fed by U10:9 (74LS133) which takes in a bunch of
> > address / control lines and's them and inverts.  So if anything isn't
> > set it will output false.
> >
> >
> >
> > One of those intputs (pin 4) is from U16:13 a MC14078 (8 input NOR).
> > Ensuring that a bunch of other things are not set which gives us a
> > enable latch of A55B.
> >
> >
> >
> > Problem I am having is one of the inputs to U16 is pin 5 which it IORQ!.
> >
> >
> >
> > When I try to write to A55B with fluke to latch that the memory
> > protect, IORQ! Is always high.  So U16:13 is low, which make U10 fail the
> and.
> >
> >
> >
> > I verified IORQ! Is working (I can run the UUT) and see it toggle.
> >
> >
> >
> > Reading the spec's on the Z80 control signals I think that should be
> > pulled low whenever the CPU is doing a write.  But it's not when doing
> > so from the fluke.
> >
> >
> >
> > I could jumper U10:4 to ground in some manner but would rather
> > understand what is happening.
> >
> >
> >
> > Ideas?
> >
> >
> >
> > Thanks,
> >
> > David
>
> Isn't IORQ! only active when you are above FFFFh? Very rusty on Z80 coding,
> and looking through the Osborne's Some Real Micros isn't helping my memory.
>
> Check section 7 starting around page 7-16
>
> John :-#)#
>
> --
>                   John's Jukes Ltd.
> 7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3 Call (604)872-5757
> (Pinballs, Jukes, Video Games)
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>   "Old pinballers never die, they just flip out"
>
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