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Hello!
I want to make a 512K SRAM Developer Cart with the Phantasy Star Cartridge. I want to use the KM684000 chip for this. Is this possible? Can you *please* provide me with some information about that? (pin-out's, board schematic, mapping). I have just built the SMS Reader, a 32K and a 256K SRAM Cart which all works fine but now I want to go on to the next step and build a "big" 512K Cart with Savegame possibility. Please help me, I'm a bloody newbie... :-(

PS: for Mike G. - I want to say THANK YOU for showing us all how to build the SMS Reader; what a GREAT tool! Keep on with the good work!

Thomas from Austria

The only difference between a 256kB SRAM DIL and a 512kB SRAM DIL is the 512k has A18 connected to pin 1 where the 256k has a N.C. so if you've built the 256k cart, then you can easily build the 512k cart.

let us know if you need more info.

a s out.

Quote

> The only difference between a 256kB SRAM DIL and a 512kB SRAM DIL is the 512k has A18 connected to pin 1 where the 256k has a N.C. so if you've built the 256k cart, then you can easily build the 512k cart.

Actually, the way I did the 256K cart in the SMSReader tutorial was to use a sandwich of 2 128K chips. The 256K chips aren't as easily available (or anywhere near as cheap) and I wanted to keep the parts cost below GBP £15.

This also means that the 512K cart with 512K SRAM chip is much easier to build than the 256K cart as shown in the tutorial, since there's no need for the sandwiching technique.

Mike

Quote

> I want to make a 512K SRAM Developer Cart with the Phantasy Star Cartridge. I want to use the KM684000 chip for this. Is this possible? Can you *please* provide me with some information about that? (pin-out's, board schematic, mapping). I have just built the SMS Reader, a 32K and a 256K SRAM Cart which all works fine but now I want to go on to the next step and build a "big" 512K Cart with Savegame possibility. Please help me, I'm a bloody newbie... :-(

> PS: for Mike G. - I want to say THANK YOU for showing us all how to build the SMS Reader; what a GREAT tool! Keep on with the good work!

Cheers! Here's the pinout of the KM684000 512K SRAM:






     +--()--+


 A18 | 1  32| Vcc


 A16 | 2  31| A15


 A14 | 3  30| A17


 A12 | 4  29| /WE


  A7 | 5  28| A13


  A6 | 6  27| A8


  A5 | 7  26| A9


  A4 | 8  25| A11


  A3 | 9  24| /OE


  A2 |10  23| A10


  A1 |11  22| /CE


  A0 |12  21| I/O7


I/O0 |13  20| I/O6


I/O1 |14  19| I/O5


I/O2 |15  18| I/O4


 Vss |16  17| I/O3


     +------+

Fortunately, in the Phantasy Star cartridge, there's already a battery circuit present for the existing 8K SRAM to hold saved games. Also, there's no chip sandwiching required, so this cart should be a breeze in comparison to the 256K one. I would implement the cart as follows. (Note: I'd desolder the battery before commencing work on the board, and solder it back once you're finished.)

All of this assumes that your Phantasy Star cartridge has a separate 315-5235 mapper, *not* an integrated ROM with the mapper built in. If your Phantasy Star cart *doesn't* have a 315-5235, stop reading now and find one which does! ;-)

1) Lift pins 32, 29, 22 and 1 of the SRAM and trim them back. Solder the remaining pins into the corresponding ROM holes on the board.

2) Get a 4011 quad NAND gate IC. Connect pin 14 (Vcc) of the 4011 to pin 28 of the existing 8K SRAM chip (a 6164 or 6264), and pin 7 of the 4011 to ground.

3) Connect the remaining pins of the 4011 as follows:

Pin 1: Pin 26 of the 8K SRAM
Pin 2: Pin 4 of the 4011
Pin 3: Pin 22 of the 512K SRAM
Pins 5 and 6: Pin 33 of the 315-5235 mapper IC
Pins 8, 9, 12, 13: Pin 14 of the 4011

4) Connect pin 9 of the 315-5235 to pin 1 of the 512K SRAM. Connect pin 32 of the 512K SRAM to pin 28 of the 8K SRAM.

5) Connect the Write Protect switch as described in the 256K tutorial, with the exception that the pin labelled "to pin 1 of 7673" should be connected to pin 28 of the 8K SRAM.

That's it - just check the connections, reconnect the battery, test the voltages, then off you go.

Mike

Mike you are GREAT! Thank you for this helpful Information!
Unfortunately I have this "looser" cartridge WITHOUT the separate Mapper but I'll get another. This shouldn't be a real problem.

Thomas
www.senoner.at

A dream came true! Now I have a full working 512K SRAM Cartridge! Yeah! Saving is possible, even with Phantasy Star Gaiden! Cool! Thank you for your help!

Thomas
www.senoner.at

Author	Message
Thomas Guest	Phantasy Star Cartridge Posted: Thu May 02, 2002 6:59 pm
Thomas Guest	Hello! I want to make a 512K SRAM Developer Cart with the Phantasy Star Cartridge. I want to use the KM684000 chip for this. Is this possible? Can you please provide me with some information about that? (pin-out's, board schematic, mapping). I have just built the SMS Reader, a 32K and a 256K SRAM Cart which all works fine but now I want to go on to the next step and build a "big" 512K Cart with Savegame possibility. Please help me, I'm a bloody newbie... :-( PS: for Mike G. - I want to say THANK YOU for showing us all how to build the SMS Reader; what a GREAT tool! Keep on with the good work! Thomas from Austria

asynchronous Joined: 14 Aug 2000 Posts: 742 Location: Adelaide, Australia	Posted: Fri May 03, 2002 2:01 am
	The only difference between a 256kB SRAM DIL and a 512kB SRAM DIL is the 512k has A18 connected to pin 1 where the 256k has a N.C. so if you've built the 256k cart, then you can easily build the 512k cart. let us know if you need more info. a s out.

Mike G Joined: 21 Apr 2000 Posts: 598 Location: Newcastle upon Tyne, England	Posted: Fri May 03, 2002 5:31 pm
	Quote > The only difference between a 256kB SRAM DIL and a 512kB SRAM DIL is the 512k has A18 connected to pin 1 where the 256k has a N.C. so if you've built the 256k cart, then you can easily build the 512k cart. Actually, the way I did the 256K cart in the SMSReader tutorial was to use a sandwich of 2 128K chips. The 256K chips aren't as easily available (or anywhere near as cheap) and I wanted to keep the parts cost below GBP £15. This also means that the 512K cart with 512K SRAM chip is much easier to build than the 256K cart as shown in the tutorial, since there's no need for the sandwiching technique. Mike

Mike G Joined: 21 Apr 2000 Posts: 598 Location: Newcastle upon Tyne, England	Posted: Fri May 03, 2002 6:09 pm
	Quote > I want to make a 512K SRAM Developer Cart with the Phantasy Star Cartridge. I want to use the KM684000 chip for this. Is this possible? Can you please provide me with some information about that? (pin-out's, board schematic, mapping). I have just built the SMS Reader, a 32K and a 256K SRAM Cart which all works fine but now I want to go on to the next step and build a "big" 512K Cart with Savegame possibility. Please help me, I'm a bloody newbie... :-( > PS: for Mike G. - I want to say THANK YOU for showing us all how to build the SMS Reader; what a GREAT tool! Keep on with the good work! Cheers! Here's the pinout of the KM684000 512K SRAM: +--()--+ A18 \| 1 32\| Vcc A16 \| 2 31\| A15 A14 \| 3 30\| A17 A12 \| 4 29\| /WE A7 \| 5 28\| A13 A6 \| 6 27\| A8 A5 \| 7 26\| A9 A4 \| 8 25\| A11 A3 \| 9 24\| /OE A2 \|10 23\| A10 A1 \|11 22\| /CE A0 \|12 21\| I/O7 I/O0 \|13 20\| I/O6 I/O1 \|14 19\| I/O5 I/O2 \|15 18\| I/O4 Vss \|16 17\| I/O3 +------+ Fortunately, in the Phantasy Star cartridge, there's already a battery circuit present for the existing 8K SRAM to hold saved games. Also, there's no chip sandwiching required, so this cart should be a breeze in comparison to the 256K one. I would implement the cart as follows. (Note: I'd desolder the battery before commencing work on the board, and solder it back once you're finished.) All of this assumes that your Phantasy Star cartridge has a separate 315-5235 mapper, not an integrated ROM with the mapper built in. If your Phantasy Star cart doesn't have a 315-5235, stop reading now and find one which does! ;-) 1) Lift pins 32, 29, 22 and 1 of the SRAM and trim them back. Solder the remaining pins into the corresponding ROM holes on the board. 2) Get a 4011 quad NAND gate IC. Connect pin 14 (Vcc) of the 4011 to pin 28 of the existing 8K SRAM chip (a 6164 or 6264), and pin 7 of the 4011 to ground. 3) Connect the remaining pins of the 4011 as follows: Pin 1: Pin 26 of the 8K SRAM Pin 2: Pin 4 of the 4011 Pin 3: Pin 22 of the 512K SRAM Pins 5 and 6: Pin 33 of the 315-5235 mapper IC Pins 8, 9, 12, 13: Pin 14 of the 4011 4) Connect pin 9 of the 315-5235 to pin 1 of the 512K SRAM. Connect pin 32 of the 512K SRAM to pin 28 of the 8K SRAM. 5) Connect the Write Protect switch as described in the 256K tutorial, with the exception that the pin labelled "to pin 1 of 7673" should be connected to pin 28 of the 8K SRAM. That's it - just check the connections, reconnect the battery, test the voltages, then off you go. Mike

Thomas Guest	Posted: Sat May 04, 2002 10:26 am
Thomas Guest	Mike you are GREAT! Thank you for this helpful Information! Unfortunately I have this "looser" cartridge WITHOUT the separate Mapper but I'll get another. This shouldn't be a real problem. Thomas www.senoner.at

Thomas Guest	Posted: Mon May 13, 2002 12:23 pm
Thomas Guest	A dream came true! Now I have a full working 512K SRAM Cartridge! Yeah! Saving is possible, even with Phantasy Star Gaiden! Cool! Thank you for your help! Thomas www.senoner.at

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