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  • Joined: 29 Jul 2022
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Making phantasy star with afterburner
Post Posted: Fri Jul 29, 2022 8:03 am
Last edited by crissaegrim_ on Fri Jul 29, 2022 7:50 pm; edited 1 time in total
Hello, I want to make a translated phantasy star but I can´t find any cart with sram. Instead, I found 2 copies of afterburner wich have the same mapper. Is it possible to add a sram chip, the battery, transistor, wirings,etc? I readed here someone moded and added a sram chip to this same cart, but no explanations provided.
Hope someone could help, thanks.
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Post Posted: Fri Jul 29, 2022 7:49 pm
Well, I searched the entire forum of development and find this:

Leonard Silva de Oliveira wrote
Firstly I'd like to report a 315-5235 sighting in the R-Type game cartridge. It consists of the mapper chip (315-5235)
and a 512kb rom that has the same pinout of a 27c4001 eprom. It's mpr code is MPR12002-T. Because the board had
the same pinout of a standard EPROM, I was able to use 128, 256 and 512kbytes EPROMs in it.
And more important, I was able to figure out how to connect a 8kbytes SRAM for backup (Phantasy Star). By doing that,
I discovered function of 3 pins that were unknown in the memory paging chips document from S-8 Dev Team

315-5235

PIN 24 - output pin. goes to SRAM output enable (/OE)
PIN 29 - output pin. goes to SRAM write enable (/WE)
PIN 30 - output pin. goes to SRAM chip enable (/CE)
315-5235 controls a 6264 SRAM (8kbytes). I don't know if it supports 16kb or more of SRAM.
I also had to add a SRAM power watchdog circuit and a lithyum battery in order to keep the data safely written on it.
This cartridge is being used with a ST G27C4001 (512kb) eprom burned with the japanese version of Phantasy Star.
I also used a MX28F1000PD (128kb) and a i28F020 (256b). All of them works perfectly without jumpers, straps and
such stuff ...
I hope I'm being usefull !


In this schematic of JP Phantasy Star there is a transistor named PST592F, does anyone know a replacement? another watchdog type maybe? thanks
[/img]

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Post Posted: Sat Jul 30, 2022 6:11 pm
Analyzing the original circuit , and after a lot of reading, this is my conclussion:

1) The circuit board has OR-dioded both supplies to sram, not so sure what the T529F function is
watchdog diodes.png (3.48 KB)
watchdog diodes.png

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Post Posted: Sat Jul 30, 2022 8:22 pm
Are these two Schottky diodes?
shotky.png (501.57 KB)
shotky.png

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Post Posted: Sat Jul 30, 2022 8:23 pm
2)In theory, it is possible to implement this OR diode logic circuit to manage the added SRAM chip.
watchdog OR.png (17.29 KB)
watchdog OR.png

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Post Posted: Sat Jul 30, 2022 8:27 pm
You can make this a lot faster & easier : use an FRAM (RAMTRON) instead of SRAM + battery.
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Post Posted: Sat Jul 30, 2022 8:33 pm
There is a variant using FET chip. The resistor values seem to be wrong, as a person stated " I would make the pull down higher, like 100K to reduce current through the external line. So, can I make R1 as 10K and R2 as 100K or so? And have V1 as 3.3V instead of 5V? As gate would be higher than source volt, I think it should be ok"
watchdog FET.png (29.21 KB)
watchdog FET.png

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Post Posted: Sat Jul 30, 2022 8:56 pm
ichigobankai wrote
You can make this a lot faster & easier : use an FRAM (RAMTRON) instead of SRAM + battery.


FRAM chips are nonexistent in my contry, instead I do have 4 (maybe 6 if I scavenge them from some famicom clone carts) 61c64 chips ready to use as SRAM for the mod
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Post Posted: Sun Jul 31, 2022 11:17 pm
Well, I'm going to start modding this pcb, as I already checked that I won't need extra pads in the connector edge. The only drawback is the routing of the 28 pin SRAM, but hey, It's worth the result :)

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Post Posted: Thu Apr 06, 2023 10:01 pm
Finally could finish 2 prototypes, both with problems, tested on a megadrive clone console using an adapter (tmee version)

Eprom with SMS power forum translation (spanish):

From the japanese phantasy star schematic:
-sram pin CE1 20 to pin 30 RAM CE
-sram pin 22 OE to pin 34 RD
-sram pin 27 WE to pin 31 WR
-sram pin 26 & pin 28 to diode logic backup/5v

Game works. Saving and pressing reset keeps the save file after reboot. Powering off the console causes the game to stop booting. Removing and reseating the battery solve this, but no save file remains

From Leonard Silva de Oliveira pinout (https://www.smspower.org/forums/1068-3155235SightingCorrectionToMemoryPagingChipsPageFromS8DevTeam#4920):
-SRAM pin 20 (/CE1) to PIN 30
-SRAM pin 22 (/OE) to PIN 24
-SRAM pin 27 (/WE) to PIN 29
-SRAM pin 26 left unconnected, pin 28 to diode logic backup/5v

Game behaves the same as the japanese schematic

Eprom with PS1 american release:

From the japanese phantasy star schematic:
-sram pin CE1 20 to pin 30 RAM CE
-sram pin 22 OE to pin 34 RD
-sram pin 27 WE to pin 31 WR
-sram pin 26 & pin 28 to diode logic backup/5v

Game works. Saving and pressing reset keeps the save file after reboot. Powering off the console causes the save file to be deleted

From Leonard Silva de Oliveira pinout (https://www.smspower.org/forums/1068-3155235SightingCorrectionToMemoryPagingChipsPageFromS8DevTeam#4920):
-SRAM pin 20 (/CE1) to PIN 30
-SRAM pin 22 (/OE) to PIN 24
-SRAM pin 27 (/WE) to PIN 29
-SRAM pin 26 left unconnected, pin 28 to diode logic backup/5v

Game works. Saving and pressing reset keeps the save file after reboot. Powering off the console causes the save file to be deleted

Then I started to think, that a reset signal chip was needed, so took a BA6162 from a genesis cart and connected Vin to vcc cart, BATin to battery 3.3v, Vout to Vcc of sram, Reset to 315-5235 pin 26, CS to pin 20 of SRAM. Now game starts but keeps reseting after a few seconds

At this point, I don´t know what to do next
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Post Posted: Fri Apr 07, 2023 1:12 pm
Here is the last arrangement


FEED32DD-F571-43B1-81C5-3209C7E99A1B.png (412.17 KB)
Attachment fairy
FEED32DD-F571-43B1-81C5-3209C7E99A1B.png

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Post Posted: Sat Apr 08, 2023 2:39 am
Took the thing apart, my guess is something is unconnected or bridged. Next is to compare the connections of 315-5235 to the japanese phantasy star around here (schematic). I dont think this is somewhere in the internet, so I will share it here:

TECTOY afterburner front PBC



TECTOY afterburner back PCB

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Post Posted: Thu Apr 20, 2023 12:02 am
I´m stuck, I can´t make it work correctly
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Post Posted: Sat May 27, 2023 7:47 pm
I´m taking this project againg, the only option is to get a reference diagram of monopoly/penguin land/pantasy star and compare it to my pcb. Anyone have a link or someting to look? Thanks
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Post Posted: Tue Feb 20, 2024 7:36 pm
Tried out yesterday again with another copy, but the same results.
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Making phantasy star with afterburner
Post Posted: Wed Feb 21, 2024 1:49 pm
Interesting thread. It's a little hard to follow in places but try this and see if it works:


Power/battery circuit:

Connect BA6162 pin 1 (GND) to cartridge GND and 3V battery (-ve).

Connect BA6162 pin 4 (Battery power supply) to the 3V battery (+ve).

Connect BA6162 pin 6 (Power supply output) to SRAM pin 28 (Vcc) only.

Connect BA6162 pin 8 (Power supply voltage) to cartridge Vcc.


SRAM:

Connect SRAM pin 20 (/CE1) to 315-5235 Mapper pin 30 (SRAM /CE).

Connect SRAM pin 22 (/OE) to 315-5235 Mapper pin 24 (SRAM /OE).

Connect SRAM pin 26 (CE2) to BA6162 pin 3 (CS output).

Connect SRAM pin 27 (/WE) to 315-5235 Mapper pin 29 (SRAM /WR).


Unused:

Leave BA6162 pin 5 (CSB output) not connected.

Leave BA6162 pin 2 (Reset output) not connected.


Connected this way, when the power rail drops below the battery voltage, the BA6162 will switch the SRAM to battery power and pull CE2 low which will put the SRAM into standby mode.

When power is restored to above battery voltage, the BA6162 will switch SRAM back to the power rail and pull CS to Vcc to enable the SRAM out of standby mode again.
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