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Author Topic: EPROM/Flash ROM/SRAM expansions (Read 29192 times)

Online Zozosoft

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Re: EPROM/Flash ROM/SRAM expansions
« Reply #120 on: 2014.June.12. 10:26:51 »
The hardest part removing the old socket. I putted old dead ceramic EPROM to the socket as heat dissipator :-) Without it the metal pins are melt the plastic part of the socket.
Firstly I removed most of soldering tin from the pins with desoldering pump. Then heated by hot air gun and pulled the EPROM which are pulled the socket.Carefully pull it until all pins are free moving.

Online gflorez

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Re: EPROM/Flash ROM/SRAM expansions
« Reply #121 on: 2014.June.12. 15:44:42 »
Good old times without SMD chips (not counting Nick and Dave...).

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Re: EPROM/Flash ROM/SRAM expansions
« Reply #122 on: 2014.June.13. 10:35:21 »
Here is the picture of the Z80 and Flash ROM. I shielded the cables, as you can see.

Online Zozosoft

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Re: EPROM/Flash ROM/SRAM expansions
« Reply #123 on: 2014.June.13. 10:41:44 »
Thanks! Both Z80 are totally same, see the date code!

Online Zozosoft

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Re: EPROM/Flash ROM/SRAM expansions
« Reply #124 on: 2014.June.13. 10:50:08 »
Anyway: I already found similar faulty Z80 CPUs (later another two found). All produced in Philippines.

I'm very curious about this make the mystic problems with your upgraded MICROTEAM card?

Online gflorez

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Re: EPROM/Flash ROM/SRAM expansions
« Reply #125 on: 2014.June.13. 11:33:55 »
But keep in mind that it worked fine until I started modifying the Microteam. Only a simple coincidence?

Online gflorez

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Re: EPROM/Flash ROM/SRAM expansions
« Reply #126 on: 2014.June.13. 11:36:58 »
And still working fine alone...

Online Zozosoft

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Re: EPROM/Flash ROM/SRAM expansions
« Reply #127 on: 2014.June.13. 11:49:11 »
Probably some incompatibility with modern components?

The faulty ones also have a crazy bugs, for example: can read/write I/O ports, can read memory, but at write memory some bits have random values.

Online gflorez

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Re: EPROM/Flash ROM/SRAM expansions
« Reply #128 on: 2014.June.13. 12:06:13 »
It can be.



We are not so bad..., at least we know that with a modern and faster CPU it works perfectly...!

Online Zozosoft

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Re: EPROM/Flash ROM/SRAM expansions
« Reply #129 on: 2014.June.16. 12:42:49 »
Very-very strange but found solution for gflorez's "disk operation crashing" problem!

I tried many different CPUs, it is change the effect, for example with NEC or ST CPU frozzen before the "ENTERPRISE" screen...
With new CMOS CPU are little more stable but not perfect...

And found the problem also exist with one unmodified MICROTEAM card (no SRAM and FLASH ROM), DIR A: crashing...

Finaly I putted back the original EXOS ROM, and disk worked!
then burned EXOS 2.4 to EPROM, and also worked!

Then the problem will be the FLASH chip? Tried with AM29F040, and working!

So, something very strange incompatibility with Winbond and SST chips :eek: :| :shock:

Now I'm ordering 128K AMD or MX chips and will check it.

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Re: EPROM/Flash ROM/SRAM expansions
« Reply #130 on: 2014.June.16. 16:33:25 »
I don't know why but at the end I also returned  to insert the original EXOS Rom and still had the same random errors.

Is the Microteam still under warranty? :ds_icon_cheesygrin:

Online Zozosoft

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Re: EPROM/Flash ROM/SRAM expansions
« Reply #131 on: 2014.June.26. 10:40:38 »
Quote from: Zozosoft
Now I'm ordering 128K AMD or MX chips and will check it.
The ordered AMD chips have arrived. Now testing...
« Last Edit: 2014.June.26. 15:19:11 by szipucsu »

Online gflorez

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Re: EPROM/Flash ROM/SRAM expansions
« Reply #132 on: 2016.November.23. 14:18:30 »
I have replaced successfully your Winwond  W29C011A with an AMD  AM29F010B on my old EP.

Can a Z84C0020PEC work at 4MHz as a direct replacement for the stock Z80A?

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Re: EPROM/Flash ROM/SRAM expansions
« Reply #133 on: 2016.November.23. 14:20:43 »
Can a Z84C0020PEC work at 4MHz as a direct replacement for the stock Z80A?
Yes!

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Re: EPROM/Flash ROM/SRAM expansions
« Reply #134 on: 2016.November.30. 17:07:46 »
The chips arrived.