Converting US LifeForce to JP LifeForce

dbstallman

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Recently I was able to aquire a LifeForce PCB with no sound. After getting the sound issues taken care of (dirty pins on the sound ROM), I got to work on my next task : Changing this version of Salamander/LifeForce to a better one.

For those that aren't familiar, this game had some noticable differences in the three versions of the game. In my opinion, the US LifeForce was the least of these with the JP LifeForce edging out the JP Salamander because if it's Gradius style weapon system.

MAME showed six ROMs needing to be replaced for the JP version : one 27C128, one 27C256, two 27C512s and two mask ROMs (TC531000P) that are 28 pin 1Mbit that I cannot find an EPROM equivalent of.

I have a friend in Japan who had mentioned to me a while back that he purchased a US LifeForce and had it converted to the JP version, so I got in touch with him and asked him what he used to replace those two mask ROMs. Unfortunately I had missunderstood his statement, he had converted his board to the JP Salamander, not LifeForce. :(

Determined, I looked up the pinout for the mask ROM and found that, other than a couple of pins, it was almost the same as a 27C1001/27C010. I have a lot of those sitting around, so I knew I would be able to give it a shot. There was only one problem : the 27C1001s have 32 pins. It was now time to build an adapter. I made a circuit board with a 32 pin socket on the top and two rows of 14 pin extensions on the bottom. I then wired the pins 1 to 1 except for the following : pin 2 on the socket connects to pin 22 on the extension, pin 24 on the socket connects to pin 20 on the extension (pin 22 on the socket also connects to pin 20 on the extension) and pin 32 on the socket connects to pin 28 on the extension. Pins 1, 30 and 31 on the socket are left floating.

When I finished I burned the data and fired up my board with the JP version of LifeForce. Success!

Since I couldn't find this info anywhere else on the net, I figured I would post what I did incase anyone else would like to try the conversion as well.

This is the board with the adapter in the lower left corner :
imag0731v.jpg


Here is a close-up of the adapter :
imag0733vs.jpg


And finally, some pictures of the game in action :
imag0748y.jpg


Observe the Gradius wepon system at the bottom of the screen :
imag0737u.jpg
 
I just noticed that I didn't post a picture of the bottom of the adapter. It might help someone visualize what I did a little more easily.

imag0753s.jpg
 
Too bad you didn't have any 27C301 EPROMs... then you wouldn't have needed to build any adaptor (just need to run a couple wires on each chip).

I believe those two chips just hold graphics data (and the differences between the two versions are probably not significant). What happens if you don't switch them? Does it give you a checksum error and refuse to boot?
 
Too bad you didn't have any 27C301 EPROMs... then you wouldn't have needed to build any adaptor (just need to run a couple wires on each chip).

I believe those two chips just hold graphics data (and the differences between the two versions are probably not significant). What happens if you don't switch them? Does it give you a checksum error and refuse to boot?

27C301s are still 32 pin... The mask ROM sockets are only 28. While there is room for the 32 pin chip to fit (I tried it) and hang over the edge of the socket, there are a couple of disc capacitors that make the chips rest at an angle.

And yes, with the US mask ROMs in place the board reported ROM errors and refused to boot.

Brian.
 
27C301s are still 32 pin... The mask ROM sockets are only 28. While there is room for the 32 pin chip to fit (I tried it) and hang over the edge of the socket, there are a couple of disc capacitors that make the chips rest at an angle.

You can pull those filter caps and mount them on the back side of the board.
 
You can pull those filter caps and mount them on the back side of the board.

I was thinking of doing just that at the beginning. I had tried just bending pins and rewiring the chips at first, but it ended up looking pretty "getto" :
imag0723v.jpg


The only way I could ensure that the chips wouldn't short out was to use some hot glue... I wasn't willing to do that to my board. The adapter seemd like a more reasonable solution.

Brian.
 
I have done this, but I did just bend up the eprom pins and run wires. however I did it somewhat clean by drilling a few holes through the board so no mess.
Next time I do one of these I will go for bank switching both US and JAP versions.

I was thinking of doing just that at the beginning. I had tried just bending pins and rewiring the chips at first, but it ended up looking pretty "getto" :
imag0723v.jpg


The only way I could ensure that the chips wouldn't short out was to use some hot glue... I wasn't willing to do that to my board. The adapter seemd like a more reasonable solution.

Brian.
 
I was thinking of doing just that at the beginning. I had tried just bending pins and rewiring the chips at first, but it ended up looking pretty "getto" :

Yeah, that's not terribly pretty. Using 27C301 is much cleaner though. It shares the pinout of the 28-pin masked ROM and the extra 4 pins hanging over just need to be tied high (using one wire from pin 28 of the socket). That can be stealthily done so there are no unsightly wires.
 
I have done this, but I did just bend up the eprom pins and run wires. however I did it somewhat clean by drilling a few holes through the board so no mess.
Next time I do one of these I will go for bank switching both US and JAP versions.

I might convert it furter to the Salamander Special Prize Version : www.youtube.com/watch?v=_mZEM4U5eOE

I snagged the ROMs from here : http://gamestone.co.uk/gradius/forumvb/showpost.php?p=23859&postcount=4

The game is a hacked reverse engineer of the special version made by someone in Japan. I will have to make another riser/adapter for the sound ROM (it was the same for the current conversion), but I am interested in trying it out.

If I like it enough, I will double up the EPROMS sizes and make a bank switching version between those two.

Also, I didn't think I was blazing any new ground doing this conversion but when I searched on info about it there seemed to only be a lot of discussion about how the mask ROMs make it really difficult or impossible. I figured I would put this out there to help the next person.

Brian.
 
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27C301s are still 32 pin... The mask ROM sockets are only 28.

[ Free Tech note ;-) ]

1Mb masked roms (ie. not programmable ) can access 1Mb of data using 28 pins.

Standard (JEDEC) 1Mb (programmable) eproms (27c010, 27c1001)
need at least one extra pin for programming so they can not fit on a 28 pin package.
So "programmable" 1Mb eproms need 32-pins (...there is no such thing as a 30-pin eprom... ;-)

Also, the standard JEDEC pin-out uses one of the 4 "extra" pins ( 28 pins Vs. 32 ),
for A16 (which is the high-address bit ) on pin #2 .

But because there was a demand for "mask-compatible" eproms,
(ie. moving A16 to match the 28-pin mask roms )
some manufacturers (not many...) created these.

Notably Hitachi 27c301, and SGS/Thompson and NEC 27c1000. (*)
(...these are both 32-pin eproms but are
compatible substitutes for 28-pin 1Mb mask roms )

[ (*) NB. Pretty much any "1000" eproms (ie. 27c1000, 54c1000, etc)
are MASK-compatible eproms. EXCEPT for MX chips.
For whatever reason the MX27c1000 is a standard JEDEC = 27c1001
... that screwed me up for awhile... ]

These "mask-compatible" eproms swap the A16 and OE signals on Pin #2 and Pin #24
so that the data pin matches the 28-pin mask rom.

The 4 "extra" pins (which would stick out of a 28-pin socket ) are :

#1 : VPP (programming voltage pin : not used in game play, should be tied low [GND])
#2 : ~OE (Output Enable : should be tied low [GND] to enable)
#31 : ~PGM (programming enable pin: Low to enable , ...So tie High [+5V] )
#32 : VPP ( +5V power . Obviously needs to be tied high )


Hope this helps...

Cheers,
Steph
www.Hobbyroms.com
 
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The 4 "extra" pins (which would stick out of a 28-pin socket ) are :

#1 : VPP (programming voltage pin : not used in game play, should be tied low [GND])
#2 : ~OE (Output Enable : should be tied low [GND] to enable)
#31 : ~PGM (programming enable pin: Low to enable , ...So tie High [+5V] )
#32 : VPP ( +5V power . Obviously needs to be tied high )

A couple corrections (according to the datasheet):

VPP should be tied to VCC (+5V) for normal Read operation.
Pin 32 is VCC (typo! :D )
So you can tie them all high, with the exception of the Output Enable, which is active low (this old ROMref.txt incorrectly shows it as active high).
 
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Well, it looks like I needed to do a little more actual repairing on this PCB.

I had the board running in on of my JAMMA setups while I replaced the power supply in the test bench system. I got the new switcher installed and fired up another board to make sure all was well now. After a couple of successfull games of Raiden II, I turned around and was greeted with this :
imag0758ld.jpg


It was at this point that I realised I hadn't heard the attract sound for LifeForce for about 5 minutes. Since I had seen something like this while I was building the adapter, I wasn't too concerned. This is the intial RAM/ROM test screen, but if it cannot read the character ROMs (the two that needed the adapter) it stops with something like this.

I adjusted the adapter to ensure it was getting good contact on the pins but the screen didn't get any better. After about 15 minutes of working with it, I decided to just put the US ROMs back in. Unfortunately, I was greeted with the exact same screen.

I broke out the logic probe and found some funny signals at the LS245 at location 19B. Piggybacking an new 245 on top of it gave me this :
imag0759j.jpg


Better, but still not quite right. :/ A little more probing found another LS245 acting up, the one at 17D. These two buss controllers are connected to the program ROMs and character ROMs respectively. Another piggybacked new 245 and I now got :
imag0761s.jpg


Back in business!! Hooray!

Here are the two new chips installed in sockets (the old ones were made by everyone's favorite manufacturer, Fairchild):
82701649.jpg


Now to get to work on converting it to the "Salamander Special Prize Version" :D

Brian.
 
Sorry guys....

I have scoured through all my picture archives and have been unable to find these images.

I'll try to get some new ones together or just write up an entire tutorial about the conversion.

The only real problem I have right now is this : a friend wanted me to do the same to his PCB. Since I was planning to make the conversion on my own board 4-way selectable with US Lifeforce, JP Lifeforce, Salamander and the Salamander Special Prize version I just moved the adapters over to his PCB to save time on his conversion. I don't have my original adapters any longer. I have something similar that I am working on for the other conversion, though.

I'll get something up this week.

Brian.
 
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