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Author Topic: EPROM/Flash ROM/SRAM expansions (Read 27621 times)

Offline Zozosoft

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Re: EPROM/Flash ROM/SRAM expansions
« Reply #135 on: 2016.December.01. 08:19:32 »
The chips arrived.
Looks good!
If my memory test will detect as CMOS Z80 then these are not fakes. The 1992 date code looks good. Chinese fakes have few years old date code.

Offline gflorez

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Re: EPROM/Flash ROM/SRAM expansions
« Reply #136 on: 2016.December.01. 09:14:56 »
There aren't traces of manipulation, the pins perfectly aligned, aparently not inserted.

Offline gflorez

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Re: EPROM/Flash ROM/SRAM expansions
« Reply #137 on: 2016.December.19. 12:03:41 »
Definitively the two chips are CMOS, but I still have to weld some components.

Offline gflorez

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Re: EPROM/Flash ROM/SRAM expansions
« Reply #138 on: 2017.January.20. 12:35:58 »
What happens when two(or more) instances of the same Rom are found on the memory map?

Edit: it seems to work on the emulator.
« Last Edit: 2017.January.20. 12:50:19 by gflorez »

Offline Zozosoft

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Re: EPROM/Flash ROM/SRAM expansions
« Reply #139 on: 2017.January.20. 13:03:45 »
EXOS have a ROM equality check.

Offline gflorez

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Re: EPROM/Flash ROM/SRAM expansions
« Reply #140 on: 2017.January.20. 14:58:18 »
Is that check original or introduced by you?

One question more: does it check also the version?

I already know a similar behaviour of EXOS when managing new drivers.
« Last Edit: 2017.January.20. 16:18:32 by gflorez »

Online SlashNet

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Re: EPROM/Flash ROM/SRAM expansions
« Reply #141 on: 2017.December.26. 08:39:07 »
I extract from old videocard this chip.
It can be useful for installing into cartridge (I have 1 free socket) or into EP?
I'm not very good in hardware.

Offline gflorez

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Re: EPROM/Flash ROM/SRAM expansions
« Reply #142 on: 2017.December.26. 10:38:20 »
That chip is called OTP-ROM(one-time programmable), essentially the same chip as EPROM. From factory it comes empty of information, ready to burn, but as it doesn't have a transparent window to apply U-V rays to the circuits, it can't be erased.

You can't use it on EP, as it comes with incompatible code.
« Last Edit: 2017.December.26. 10:43:32 by gflorez »

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Re: EPROM/Flash ROM/SRAM expansions
« Reply #143 on: 2017.December.26. 10:45:01 »
Thanks.

I wanted to know if that chip can be programmable and it electrically compatible.
Now I understand.


« Last Edit: 2017.December.26. 10:53:04 by SlashNet »

Offline Zozosoft

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Re: EPROM/Flash ROM/SRAM expansions
« Reply #144 on: 2017.December.26. 11:45:14 »
I'm not sure now, but I have something similar chip which is Winbond 27EE... compatible, these are electricaly eraseable EPROMs.
Will look about it when I'm at home.

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Offline gflorez

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Re: EPROM/Flash ROM/SRAM expansions
« Reply #146 on: 2017.December.26. 14:05:15 »
The data sheet says it is OTP.

On the other side, a 64Kb EPROM is only usable for the internal EXOS 2.4 hack or for a 1 socket cartridge, but not for a two sockets cartridge, as the total  addressable memory is only 64Kb and supposedly you have 16KB already occupied by the Basic ROM.
« Last Edit: 2017.December.26. 14:19:42 by gflorez »

Offline Zozosoft

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Re: EPROM/Flash ROM/SRAM expansions
« Reply #147 on: 2017.December.28. 13:45:46 »
but I have something similar chip which is Winbond 27EE... compatible, these are electricaly eraseable EPROMs.
Found it, It is a another thing: ASD AE27E256

And I also have a AMIC A276308A, and yes it is OTP. My one empty at the first half (32K), this can be used for EP, just need Pin 1 connected to GND :-)

Quote
64Kb EPROM is only usable for the internal EXOS 2.4 hack or for a 1 socket cartridge, but not for a two sockets cartridge, as the total  addressable memory is only 64Kb and supposedly you have 16KB already occupied by the Basic ROM.

For a two socket cartridge possible solutions: use only partialy the 64K EPROM.
Or hack the cartridge: connect directly the CART signal to EPROM CE (and also the required address lines), and use only one socket. Or done this for both socket, and put a switch for EPROM selection.

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Re: EPROM/Flash ROM/SRAM expansions
« Reply #148 on: 2017.December.28. 18:05:28 »
Thank you for the information.

It will be useful for me at next year.