ESWAT/Golden Axe De-suicide/Conversion

I had been searching for a Golden Axe PCB for a while and after being pipped at the post every time one came up for sale, I saw on UKVAC that alpha1 had an ESWAT for sale.  cmonkey had also posted in the thread to say that this PCB could be converted to Golden Axe so I asked cmonkey if it was an easy conversion (by which I meant no soldering) and he confirmed it was, so I grabbed it.

The ROM board is the 171-5797.  The conversion was seemingly easy, grab the decrypted program ROMs from Porchy's website, burn the other ROMs from MAME, change the jumpers according to the MAME driver (which according to the MAME file are for ROM size) and your done.

I looked at the MAME driver (segas16b.c) and the details for Golden Axe (lines 635-669) showed a differing number of ROMs to the Golden Axe ROM file.  On further inspection the ROM numbers for row B matched those of Shinobi and not Golden Axe (Row A matched Golden Axe).  I spoke to cmonkey who confirmed that the MAME driver was incorrect.  I wanted to burn the ROMs as per the MAME driver to see what would happen, but cmonkey talked me out of this (I might still do it).

I burnt the ROMs, using 27c020's for IC's 1-2 and 9-14 and 27c010's for IC's 19-21 and 6.  I changed the jumpers and it seemingly worked.  However The sound was wrong and the background graphics were missing from level 3 onwards.  At first I thought it was the ROMs however I checked the ROMs and all were fine, I then replaced all the ROMs in case one was faulty but no change.  I wondered if the board was faulty however it worked perfectly as ESWAT.

cmonkey suggested speaking to Porchy and Porchy said to try different program ROMs in case the encryption removal had failed on one of the dumps.  I tried all the variants of the program ROMs and no change.  Porchy then suggested that maybe all the dumps may not be working as testers may not have checked past level 2, however cmonkey built a version of MAME from source specifically for these dumps to test and confirmed that they were working fine all the way through.

Another ESWAT board came up for sale so I grabbed it in case it was a problem with the board.  The new ESWAT arrived and the problem still existed!

I had my suspicions that the issue was down to the use of JEDEC ROMs for the video/audio so ordered some from China and I am currently waiting for them to turn up.  I then saw an original Golden Axe up for sale on UKVAC, it had a very high res picture, so I could zoom in.  The jumpers were the same - good, looked at the ROMs and IC's 19-21 and 6 had non-JEDEC Roms (m27c1000).  Soon after a Golden Axe conversion came up for sale, again jumpers the same and IC's 19-21 and 6 were again non-JEDEC (27c301).  Realising that when my non-JEDEC ROMs will turn up it will solve the issue, I messaged cmonkey and Porchy to break the good news.

cmonkey came back and said maybe the jumpers also decide the ROM type.  I had thought of this before but the MAME file says S1-S16 configure ROM sizes and my multimeter is elsewhere so hadn't checked.  Looking around I found a diode tester and thought I would try it.  I tested the pins closest to the ROMs and got funny results.  I assumed this was because i was using a diode tester.  I then tested the pins furthest away from the ROMs and BINGO!  Jumpers S1 and S2 were both connected to Pin 2 of the Video ROM, Jumper S5 and S6 were both connected to Pin 24.  I then checked all the jumpers and these are the results:

Jumpers S1-S6 : IC's 19-21
S1: A16 to Pin 2 (short for JEDEC ROMs, open for non-JEDEC ROMs)
S2: OE to Pin 2 (open for JEDEC ROMs, short for non-JEDEC ROMs)
S3: ROM size 1mbit (short for Golden Axe, open for ESWAT)
S4: ROM size 2mbit (open for Golden Axe, short for ESWAT)
S5: A16 to Pin 24 (open for JEDEC ROMs, short for non-JEDEC ROMs)
S6: OE to Pin 24 (short for JEDEC ROMs, open for non-JEDEC ROMs)
 
Jumpers S7-S10 : IC's 9-14 and 22-23 (all 2mbit)
S7: OE to Pin 24 (short for JEDEC ROMs, open for non-JEDEC ROMs)
S8: A16 to Pin 24 (open for JEDEC ROMs, short for non-JEDEC ROMs)
S9: A16 to Pin 2 (short for JEDEC ROMs, open for non-JEDEC ROMs)
S10: OE to Pin 2 (open for JEDEC ROMs, short for non-JEDEC ROMs)

Jumpers S11-S16 : IC's 6-7
S11: A16 to Pin 2 (short for JEDEC ROMs, open for non-JEDEC ROMs)
S12: OE to Pin 2 (open for JEDEC ROMs, short for non-JEDEC ROMs)
S13: ROM size 1mbit (short for Golden Axe, open for ESWAT)
S14: ROM size 2mbit (open for Golden Axe, short for ESWAT)
S15: A16 to Pin 24 (open for JEDEC ROMs, short for non-JEDEC ROMs)
S16: OE to Pin 24 (short for JEDEC ROMs, open for non-JEDEC ROMs)

IC's 1-2 Don't appear to have any jumpers connected so are always JEDEC ROMs.

Hopefully this will help someone in repairing/de-suiciding/converting an ESWAT/Golden Axe.

It also means that in theory, it is possible to have a dual ESWAT/Golden Axe by bank selecting the ROMs with remote jumpers for S3/S4 and S13/S14, but that is a project for someone else.

Many thanks to both cmonkey and porchy for helping me getting this resolved.


Edited by simonden - 06 March 2015 at 8:08pm