32Mbit Multirom 2in1 diagram

[Kayumba]

Hello,

Can somebody share schematic diagram for 32Mbit Multirom EPROM 2in1 ?
I tried to use 74HC74 flip-flop chip for 2 games x 16Mbit with this diagram but it doesn't work.
I use method of combine two files with command line "copy /b"
Thank for help.

[poorstudenthobbyist]

https://thepoorstudenthobbyist.com/2020 ... -overview/

[Kayumba]

https://thepoorstudenthobbyist.com/2020 ... -overview/

Thank you!

[Kayumba]

https://thepoorstudenthobbyist.com/2020 ... -overview/

So, if i get right...
- For 2X16mbit on one 322 eprom: use adress pin A21
- For 4X8mbit on one 322 eprom: use adress pin A21 and A20

Is that right?

[poorstudenthobbyist]

Technically A20 and A19, since it's a 16-bit databus, but yep the highest address pins.

[Kayumba]

Technically A20 and A19, since it's a 16-bit databus, but yep the highest address pins.

Why technically ?

[lidnariq]

The datasheet for the 27C322 calls those pins A19 and A20.

But in a machine using a 68000, those same pins are connected to 68k A20 and A21.

[Kayumba]

The datasheet for the 27C322 calls those pins A19 and A20.

But in a machine using a 68000, those same pins are connected to 68k A20 and A21.

I tried to do for 4in1 (4x8Mbit) like that, but it's doesn't work ...
Why? Is there something wrong?

For LoROM :
A21=> pin 42 (27C322)
A20=> pin 1 (27C322)

[lidnariq]

crop_38ce5c6eae8cf7c71d7ed38bd2f56285.jpg (14.85 KiB) Viewed 2219 times

Uh. You might to look more closely at what you wrote.

[Kayumba]

crop_38ce5c6eae8cf7c71d7ed38bd2f56285.jpg

Uh. You might to look more closely at what you wrote.

Thats why it not working

Here is corrected visual schematic for 27C322 LoROM / HiROM with 74HC74 flip-flop chip:


How about SAVES ?
Will it works to save game progress ?
If for example, I have one file with 2 games that each of ONE need SRAM 6264 (8kB), can I keep ONE SRAM 6264 for two games?
Or better to put bigger SRAM, like 62256 ?

[Kayumba]

I I will use 2in1 multirom,
How to do if both 2 games will using 64K SRAM CHIP ?
Will it work with one ?

[poorstudenthobbyist]

Apply the same method in the multicart article to the SRAM. It holds data in the same way as a ROM does (it just gets erased if power is removed).

[Kayumba]

Apply the same method in the multicart article to the SRAM. It holds data in the same way as a ROM does (it just gets erased if power is removed).

Ok,
but Will it be good enough one SRAM 64 for two games that each one need 64 ?

[poorstudenthobbyist]

Can you put two 32Mbit ROMs on one 27C322?

[Kayumba]

Can you put two 32Mbit ROMs on one 27C322?

No.
I talking about 2 games x 16Mbit = 32 Mbit (27C322 Multirom)

But each 16Mbit game need 6264 SRAM.
If on my board I will keep one 6264 SRAM, I dont know how each game will save data, will it be good enough space for each one?