Anyway to a MultiGame cartridge ?

[bastien]

Hi
I want to make a multi-game cartridge for sega genesis.
I think i will make it with an Eprom type 27c322 (4Mo).

I have already make a lot of home-made cartridge based on real Genesis PCB with a pirated roms in an Eprom, for exemple this :







( i have made another of it : Monster World IV Fr , Phantasy Star III FR , ect .... )

but now i would make a multi-game cartridge.

So My question is
do you have a rom with a special menu for it ?

or is it possible to use bankswitch method with the reset button for changing game ? ( do you have a shema or a method ).

That's all for now and oh excuse my bad english

[Shiru]

I've seen unlicensed multi-game cartridge for SMD with meny only once, all other (tons of) multi-game carts had game switching by reset.

I don't have ready-to-use schematic, but it must be very simple - couple of triggers or binary counter (depends from how many games you need to switch), input to reset, outputs to top address lines of the ROM. It is about 1-2 low-intergration ICs.

[bastien]

ok thanks for the answer .
i want switch 4 game so 1 per Mo ( 1-1-1-1) for 32Mbit.
i have found this :

http://www.raphnet.net/electronique/gen ... t_cart.png

but it's for flash 2x 512k..

can you draw me a little shema ?

[Shiru]

You could do almost the same, except you should use two outputs of 74LS90 instead of one. As you can see, it first output (QA) goes (through jumper) to A18, thus every reset switches between top and bottom half of the ROM. 2x512K does not matter, these are 8-bit ROM's, so you can think about them as single 512 16-bit KWords.

As you want to have four games, you'll need to connect QA and QB of 74LS90 to two higher A lines of your ROM. Size and type of ROM does not matter. In this case every reset will switch between four parts of same size of the whole ROM.

[bastien]

ok but for adapt an Eprom 27c322( for 32 MBit game 4x1Mo ) i already use A18, A19 and A20:



-A18 ---> cartridge B7
-A19 ---> cartridge B8
-A20 ---> pin5 74HCC00 ( for game with Sram ) or B9 cartridge

[Shiru]

Without SRAM you need to simply disconnect A19 and A20 of ROM from any other lines, and connect them (A19 and A20) to 74LS90 outputs. With SRAM it is more difficult, can't answer without having the schematics how the SRAM connected (never actually looked into that).

[bastien]

i think i will make one without Sram for the beginning.
ok if i draw a shema you can talk me if it's correct ?

[Shiru]

Yes, no problem.

[bastien]

question
do i need to redirect a thread: cartridge port to Multigame cartridge for the "reset" ?
or i can adapt just a classical sega cartridge ( 40 or 42 pin maskrom) ?

here is my first shéma but i have made nothing for the reset button ...:

[bastien]

Shiru ?
could you help me ?

[Shiru]

Sorry, missed your answer.

Didn't get your question, though. Pin 14 of 74LS90 should be connected with B27 of the cartridge slot. I don't know what the classical sega cartridge is, the original cartridges were uncommon here, and they were of all sorts (J,U,E, etc).

[TmEE co.(TM)]

if I have a bunch of tiny games, I'd have a game selector, and I'd use the !Time singal to manage stuff... of course it will mess everything up if a game thingks it needs to use SRAM

[bastien]

Sorry, missed your answer.

Didn't get your question, though. Pin 14 of 74LS90 should be connected with B27 of the cartridge slot.

Hmm ok but if i put my thread is it ok ?:



So Pin14 74LS90 to the B27 connector of the PCB
I think there is no more différencies between JUE PCB just the game in the Maskrom are différent.
And sure for An Sram game the schema isn't correct

Are you Ok with this ?

[HardWareMan]

You making an Reset based switching multigame cartrige? Ok, I'll help you.
First, you choosed 74xx90 for switching high address bits. It is an BCD counter and you do not properly set it's operational mode. It countains one separate trigger, wich has CLK input (CKA) and output (Qa) and 3-bit counter, wich has input (CKB) and three outputs (Qb, Qc and Qd).
Second, there 2 types of reset signals: R0.0 + R0.1 (logical AND) and R9.0 + R9.1 (logical AND). R0 sets counter to 0 (all outputs sets to 0) and R9 sets it to 9 (Qa=1, Qb=0, Qc=0 and Qd=1). So, to allow counter step up on every CLK high-to-low change you must connect R0 and R9 to ground (GND).
Third, with your schema you will never get Qb changes, becouse it not belong to CKA input. So, you must connect CKB to Qa, or use CKB as input and Qb + Qc as high address signals.

I hope it helps you.

Example 1:
14 => B27
12 => 1
12 => A19
9 => A20
5 => VCC
2 => GND
3 => GND
6 => GND
7 => GND
10 => GND

Example 2:
1 => B27
9 => A19
8 => A20
5 => VCC
2 => GND
3 => GND
6 => GND
7 => GND
10 => GND

[bastien]

Ok

First thank you very munch for helping me hardware Man :

but i have a little thing i don't understand :

-I want to use an Eprom type 27c322 and for put this in the original PCB i must redirect A18 ( to B7) , A19 ( to B8 and to pin 12 exemple 1 ) and A20 ( to B9) but i also must use this pin for make the reset based switching multigame cartrige...

-

Example 1:
14 => B27
12 => 1
12 => A19
9 => A20
5 => VCC
2 => GND
3 => GND
6 => GND
7 => GND
10 => GND

Example 2:
1 => B27
9 => A19
8 => A20
5 => VCC
2 => GND
3 => GND
6 => GND
7 => GND
10 => GND

Thanks you very much for your exemple is it for 4x 1Mo ?

Excuse me for my bad english , and another thanks for help me.

Finally i will remake my shéma so i think this is correct for the 4x1Mo with a switch per 1mo ( four 1Mo game ):