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Author Topic: [how to] convert HVC-UNROM to UOROM  (Read 11928 times)
famifan
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« on: June 10, 2012, 05:30:05 PM »

hey there!

the board i will use HVC-UNROM-03 from Hector'87

http://wiki.nesdev.com/w/index.php/UOROM <-- here you can find very confusing ascii picture of mapper (but maybe it's just me and i don't understand the picture until i've reversed the actual board's mapper schematic on the sheet of paper)

i'm finished with a little reseach on UNROM/UOROM schematic and now it is clear to me what i need to do to perform the $SUBJ

i'm going to recreate what i've researched in real hardware and publish some usefull information here if i've succeeded.

is anybody else interested in that? or is it so clear, easy and obvious for everyone to do this without any help?  Question-Mark Block
=====
UPD:
so, finally i've made 'battle kid' repro from HVC-UNROM.
if you know some other good UOROM games, plz let me know!

have any question? feel free to ask!

thank for reading && happy board converting!
« Last Edit: June 11, 2012, 01:31:08 PM by famifan » Logged
80sFREAK
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« Reply #1 on: June 10, 2012, 10:25:30 PM »

Just do it. It will be for Famicom, not for NA, not for S16 and not for ND.
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jpx72
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« Reply #2 on: June 11, 2012, 10:13:58 AM »

I'm not sure if I understand it correctly but if you are going to do a manual on how to convert UNROM to UOROM then I'm highly interested!!! Starman
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80sFREAK
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« Reply #3 on: June 11, 2012, 11:33:47 AM »

Oh LOL, just went thru some links. That's EPIC.
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famifan
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« Reply #4 on: June 11, 2012, 12:55:55 PM »

k
let's start with the schematics.

as you can recognize HVC-UNROM lacks D3 bit decoding circuit and that is all the differences between HVC-UNROM and UOROM. And all unused input mapper pins are connected to VCC and outputs are connected to nothing ("Not connected" aka NC).

so in order to add this circuit you need to :
1) disconnect unused #6 pin of 74xx161 from VCC
2) disconnect two unused #9, #10 pins of 74xx32 from VCC
3) solder a junction between #9 pin and any of #12, #2, #5 pins of 74xx32. So in the result those pins (#2, #5, #12, #9) should be connected all together.
4) connect #11 pin of 74xx161 to #10 pin of 74xx32
5) connect #6 pin of 74xx161 to D3 pin of ROM
6) connect #8 pin of 74xx32 to A17 pin of ROM

i've cut those pins by half and soldered wires to the remaining part of the pins. The convertion to UOROM is complete!

NOTE: don't forget about the mirroring! (as i did and got strange graphical glitches)
NOTE2: if you swap the wires connected to #9 and #10 pins of 74xx32 the assembling would a bit be easier and this is completely safe.
« Last Edit: June 11, 2012, 01:27:29 PM by famifan » Logged
jpx72
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« Reply #5 on: June 11, 2012, 05:15:43 PM »

Great work! Thanks for sharing the info! Those UOROM donors are so scarce....
BTW Guardian Legend!
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number47
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« Reply #6 on: May 15, 2015, 05:34:50 AM »

Sorry for necroposting.
I don't know if anyone cares, but yesterday I managed to convert UN1ROM to UNROM.
Now my former Senjou no Ookami board has the PRG maskrom from Dragon Quest 2 board.
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HVC-Man
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« Reply #7 on: May 17, 2015, 03:01:05 AM »

Have any of you tried UNROM to AOROM? NESdev has instructions for it and it didn't work on a regular HVC-UNROM board for me.

UNROM -> AOROM conversion (mapper 7):
Bend up pins 1, 2, 24, 30 and 31
remove '32 chip
cut track to pin 6 of '161
Solder pin 2 to pin 13 of '161 (A16)
Solder pin 18 to pin 6 of '161 (D4)
Solder pin 24 to GND (OE)
Solder pin 30 to pin 12 or '161 (A17)
Bridge gap between pins 10 and 11 where '32 was (A14)
Bridge gap between pins 3 and 13 where '32 was (A15)
remove solder gap for either V or H
Solder NES pin 22 (CIRAM A10) to pin 11 of '161
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number47
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« Reply #8 on: May 22, 2015, 09:20:55 PM »

Just wasted two days to figure out this instruction is faulty.

You can't bridge 3 and 13, because it shorts A17 and A15.
Bridging 3 and 4 makes a lot more sense - it connects A15 pin 14 on '161 (according to http://www.raphnet.net/electronique/nes_cart/rom.txt scroll down to NES-AOROM)

Now I managed to trace the bug in this tutorial. My Battletoads from UNROM board is alive!

So the REAL guide of transforming UNROM to AOROM is as follows:

UNROM -> AOROM conversion (mapper 7):
Bend up pins 1, 2, 24, 30 and 31
remove '32 chip
cut track to pin 6 of '161 (I cut the leg as near to the board as possible and bended up)
Solder pin 2 to pin 13 of '161 (or hole 1 of removed chip '32)
Solder pin 18 to pin 6 of '161
Solder pin 24 to GND (OE)
Solder pin 30 to pin 12 of '161 (or hole 13 of removed chip '32)
Bridge gap between pins 3 and 4 where '32 was
Bridge gap between pins 5 and 6 where '32 was
remove solder gap from either V or H
solder middle tab of V/H pads to pin 11 of '161
Edit: one more thing - solder pins 31 and 32 to hole 28
« Last Edit: July 19, 2017, 10:21:28 AM by number47 » Logged
HVC-Man
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« Reply #9 on: May 23, 2015, 12:46:10 AM »

I tested your corrected instructions with Battletoads & Double Dragon, it works! Thanks so much for figuring out what was wrong.
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KCRX85X
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« Reply #10 on: July 15, 2016, 09:20:51 PM »

Hi there I also tried to make a Battletoads & Double Dragon and Wizards & Warriors 3 with this instruction but I keep getting glicthing graphics.

Iv tried 2 different UN boards and 2 different games.

Edit:

And I noticed I was tired yesterday and did connect a cable in the wrong place... on both boards... so I can also verify that the UN to AO convert works!
« Last Edit: July 16, 2016, 06:55:42 PM by KCRX85X » Logged
Kabazorro
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« Reply #11 on: July 16, 2017, 02:37:00 PM »

Hello everyone this is my first message in the group, I came looking for help, try to follow all the steps to convert unrom to aorom, but I did not understand the part of Solder middle tab of V / H pads to pin 11 of '161 , I also noticed a mistake, I solder pin 31 and 32 eprom in pin or hole 26 and it was in pin 28, and I fix it. I leave a photos to see if someone helps me, the game I want to do is rc pro am 2, memory I use eprom is AM27c020.

If someone can respond with scheme, or a photo of your game would be great because sometimes the translation I do is not good and causes me conflict.

Greetings to all and forgive my bad English.
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number47
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« Reply #12 on: July 16, 2017, 06:50:35 PM »

I see your problem - you are using a NES cartridge. Mirroring is a bit different. You have to remove all the solder that is marked with yellow and connect the wire to the solderpad that is connected to the pin that is marked with the red line.

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Kabazorro
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« Reply #13 on: July 16, 2017, 07:44:49 PM »

Hi, pin 21 CHR / RD? I thought that maybe it was in pin 22 Ciram A10
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number47
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« Reply #14 on: July 17, 2017, 03:23:42 AM »

Sorry for drawing with offset - yes mirroring is CIRAM A10.
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