32Mbit Multirom 2in1 diagram

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Kayumba
Posts: 246
Joined: Sun Mar 01, 2020 2:36 am

32Mbit Multirom 2in1 diagram

Post by 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. :cry:
I use method of combine two files with command line "copy /b"
Thank for help.
Image
Kayumba
Posts: 246
Joined: Sun Mar 01, 2020 2:36 am

Re: 32Mbit Multirom 2in1 diagram

Post by Kayumba »

Kayumba
Posts: 246
Joined: Sun Mar 01, 2020 2:36 am

Re: 32Mbit Multirom 2in1 diagram

Post by Kayumba »

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
Posts: 252
Joined: Fri Jun 24, 2016 4:20 pm

Re: 32Mbit Multirom 2in1 diagram

Post by poorstudenthobbyist »

Technically A20 and A19, since it's a 16-bit databus, but yep the highest address pins.
Kayumba
Posts: 246
Joined: Sun Mar 01, 2020 2:36 am

Re: 32Mbit Multirom 2in1 diagram

Post by Kayumba »

poorstudenthobbyist wrote: Wed Feb 03, 2021 8:49 am Technically A20 and A19, since it's a 16-bit databus, but yep the highest address pins.
Why technically ?
lidnariq
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Joined: Sun Apr 13, 2008 11:12 am

Re: 32Mbit Multirom 2in1 diagram

Post by 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
Posts: 246
Joined: Sun Mar 01, 2020 2:36 am

Re: 32Mbit Multirom 2in1 diagram

Post by Kayumba »

lidnariq wrote: Wed Feb 03, 2021 4:13 pm 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)

Image
lidnariq
Posts: 11432
Joined: Sun Apr 13, 2008 11:12 am

Re: 32Mbit Multirom 2in1 diagram

Post by lidnariq »

crop_38ce5c6eae8cf7c71d7ed38bd2f56285.jpg
crop_38ce5c6eae8cf7c71d7ed38bd2f56285.jpg (14.85 KiB) Viewed 6762 times
Uh. You might to look more closely at what you wrote.
Kayumba
Posts: 246
Joined: Sun Mar 01, 2020 2:36 am

Re: 32Mbit Multirom 2in1 diagram

Post by Kayumba »

lidnariq wrote: Wed Feb 03, 2021 7:38 pm
crop_38ce5c6eae8cf7c71d7ed38bd2f56285.jpg
Uh. You might to look more closely at what you wrote.
Thats why it not working :lol:

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

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
Posts: 246
Joined: Sun Mar 01, 2020 2:36 am

Re: 32Mbit Multirom 2in1 diagram

Post by 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
Posts: 252
Joined: Fri Jun 24, 2016 4:20 pm

Re: 32Mbit Multirom 2in1 diagram

Post by 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
Posts: 246
Joined: Sun Mar 01, 2020 2:36 am

Re: 32Mbit Multirom 2in1 diagram

Post by Kayumba »

poorstudenthobbyist wrote: Tue Feb 09, 2021 5:49 pm 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
Posts: 252
Joined: Fri Jun 24, 2016 4:20 pm

Re: 32Mbit Multirom 2in1 diagram

Post by poorstudenthobbyist »

Can you put two 32Mbit ROMs on one 27C322?
Kayumba
Posts: 246
Joined: Sun Mar 01, 2020 2:36 am

Re: 32Mbit Multirom 2in1 diagram

Post by Kayumba »

poorstudenthobbyist wrote: Tue Feb 09, 2021 6:14 pm 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?
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