SD Keiji Blader Repro Issues

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Ice Man
Posts: 530
Joined: Fri Jul 04, 2014 2:34 pm

Re: SD Keiji Blader Repro Issues

Post by Ice Man » Sat Jan 25, 2020 1:57 am

Ah, damn, I don't have any of these ICs available right now except 74'139, 74'157 but not a problem, I can order them.
Will test it after they arrive and report back if it worked. Thanks!

Ice Man
Posts: 530
Joined: Fri Jul 04, 2014 2:34 pm

Re: SD Keiji Blader Repro Issues

Post by Ice Man » Sat Jan 25, 2020 11:30 am

Just to make sure. Would this work? I wasn't really sure about the 74'138 at all.
Attachments
a17.png

lidnariq
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Location: Seattle

Re: SD Keiji Blader Repro Issues

Post by lidnariq » Sat Jan 25, 2020 12:41 pm

Yeah, that's right.
My diagram sneakily put 74'138 pins 1-6 in order from top to bottom.
It's not necessary to hook up A8 to the 74'138, but R/W and A8 are literally the only two low signals on register access.

Are pins 60 and 62 driven? If not, do they have over/undervoltage protection diodes?

Here's a random weird thought: What if D6 and D7 are swapped on the X1-017 but the X1-017 actually did support 256KB? Then attempting to dump 256KB would fail, because the external hardware would be writing to the wrong bits.

Seems like a long shot, though.

Ice Man
Posts: 530
Joined: Fri Jul 04, 2014 2:34 pm

Re: SD Keiji Blader Repro Issues

Post by Ice Man » Sat Jan 25, 2020 12:54 pm

I think pin 60 and 62 were both low but I can test those 2 pins tomorrow and see again to make sure.

If D6 and D7 were swapped, the dump wouldn't verify for the first 128K at all. Would it?
After all, D0-D7 and A0-A12 are used for the internal 5K RAM of the X1-017 afaik.

lidnariq
Posts: 9379
Joined: Sun Apr 13, 2008 11:12 am
Location: Seattle

Re: SD Keiji Blader Repro Issues

Post by lidnariq » Sat Jan 25, 2020 1:34 pm

Pin numbers are arbitrary for RAMs - as long as the data got into the RAM the same way it got out, it doesn't matter whether it's A5 or A9, or D0 or D5. But it does raise the valid point that CHR A16 and A17 would have to be swapped too, and I believe you established it isn't.

Ice Man
Posts: 530
Joined: Fri Jul 04, 2014 2:34 pm

Re: SD Keiji Blader Repro Issues

Post by Ice Man » Tue Jan 28, 2020 6:46 am

ICs came today and soldered everything together.
Game is working. PRG is dumping fine, too!
Now to get it back in the shell somehow, XD.

Thanks so much, lidnariq!

Also, Pin 60 and 62 were low during my tests. I have no idea what their purpose is.
Attachments
tv.jpg
pcb.jpg
m82.png

Ice Man
Posts: 530
Joined: Fri Jul 04, 2014 2:34 pm

Re: SD Keiji Blader Repro Issues

Post by Ice Man » Tue Jan 28, 2020 8:50 am

And since I don't want to solder spaghetti every time I have made an adapter in KiCAD quickly.
This one will just be put on the X1-017 back side and soldered on the needed holes (or all if you want).
Attachments
prg-a17.png

lidnariq
Posts: 9379
Joined: Sun Apr 13, 2008 11:12 am
Location: Seattle

Re: SD Keiji Blader Repro Issues

Post by lidnariq » Tue Jan 28, 2020 11:39 am

Ice Man wrote:
Tue Jan 28, 2020 6:46 am
Also, Pin 60 and 62 were low during my tests. I have no idea what their purpose is.
Given that we don't know how to generate an IRQ, I wonder if the silicon inside the X1-017 is just really buggy.

One odd thought, kind of the flip side of what I suggested, is that maybe PRG A17 is broken but PRG A18 works fine. Eh...

I wonder if would be practical to integrate the PCB into the PRG ROM rework and just have one graft that handled everything instead of needing multiple separate bits of rework.

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