[sdiy] Substituing M48Z18-100 (equ of DS1225AB-100) with 28 pins DIP small pcb

Joan Touzet music at atypical.net
Mon Apr 26 01:19:40 CEST 2021


They also have a much more limited number of cycles per cell as compared
with SRAM. I believe when I last checked it was on the order of 20k
cycles per cell.

If you're using them as replacement for rarely-modified patches (as on a
cartridge) you're probably fine. I would not recommend them for
replacing general RAM in a synth or computer.

-Joan

On 25/04/2021 18:57, Ullrich Peter via Synth-diy wrote:
> Hi!
> 
> Yes the FRAMs are a nice option... I still want to use them for DX7 and
> Casio-CZ sound cartridges some time.
> 
> The parameter that could be critical is the cycle time in the data sheet.
> But as most synths are quite slow on the memory interface it will work
> in most cases I think.
> 
> Ciao
> Peter
> 
>  
> 
> 
> ------------------------------------------------------------------------
> *Von:* Synth-diy <synth-diy-bounces at synth-diy.org> im Auftrag von
> Jean-Pierre Desrochers <jpdesroc at oricom.ca>
> *Gesendet:* Sonntag, 25. April 2021 22:23
> *An:* 'synth-diy mailing list' <Synth-diy at synth-diy.org>
> *Betreff:* *EXT* Re: [sdiy] Substituing M48Z18-100 (equ of DS1225AB-100)
> with 28 pins DIP small pcb
>  
> 
> I think I’ll go for the FM16W08-SG as suggested by Jason..
> No battery worrying and it seems to fit my needs..
> 28SOIC package mounted on a SOIC to DIP carrier like this one:
> 
> Thanks !
> 
>  
> 
>  
> 
> *De :*Jason Tribbeck [mailto:jason at tribbeck.com]
> *Envoyé :* 25 avril 2021 13:00
> *À :* Jean-Pierre Desrochers
> *Cc :* synth-diy mailing list
> *Objet :* Re: [sdiy] Substituing M48Z18-100 (equ of DS1225AB-100) with
> 28 pins DIP small pcb
> 
>  
> 
> DS1225 does seem to still be available from Farnell:
> https://uk.farnell.com/maxim-integrated-products/ds1225ab-70ind/nv-sram-parallel-64kbit-edip-28/dp/2798716
> <https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fuk.farnell.com%2Fmaxim-integrated-products%2Fds1225ab-70ind%2Fnv-sram-parallel-64kbit-edip-28%2Fdp%2F2798716&data=04%7C01%7CPeter.Ullrich%40kapsch.net%7Ca0274962ed934dbc4e9708d908288bba%7C5f9ce5277e3e4e83a8a4b6c848f85ab5%7C1%7C1%7C637549792517067813%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=9S9O%2Bumo2HbMrepR%2FT2qFerjp9qv2eYW0UX9%2BkH1VDs%3D&reserved=0>
> 
>  
> 
> Or you could look at FRAM, for example Cypress FM16W08-SG :
> https://uk.farnell.com/cypress-semiconductor/fm16w08-sg/f-ram-non-vol-64kbit-soic-28/dp/2772905
> <https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fuk.farnell.com%2Fcypress-semiconductor%2Ffm16w08-sg%2Ff-ram-non-vol-64kbit-soic-28%2Fdp%2F2772905&data=04%7C01%7CPeter.Ullrich%40kapsch.net%7Ca0274962ed934dbc4e9708d908288bba%7C5f9ce5277e3e4e83a8a4b6c848f85ab5%7C1%7C1%7C637549792517067813%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=eTkeZZ09y64lIscjuteMG5C2Fly2%2FEfrVdnXEzie%2BSA%3D&reserved=0>
> 
>  
> 
> I'm pretty sure FRAM can be used in the same way as SRAM.
> 
>  
> 
> On Sun, 25 Apr 2021 at 16:02, Jean-Pierre Desrochers <jpdesroc at oricom.ca
> <mailto:jpdesroc at oricom.ca>> wrote:
> 
>     Hi list,
> 
>     I need to replace a M48Z18-100PCI (8K x 8 battery backed SRAM) in
>     one of my old
>     test equipment. It's dated 1996 so It's inner battery life is ending.
> 
>     Yeah even after 25 years it still keeps its data.. (!!!)
> 
>     It's a 28 pins 600mil DIP package.
> 
>      
> 
>     The specs say it is full Dallas DS1225 compatible.
> 
>     There are many sites who show how to hack a DS1225 package
>     to disconnect the inner battery tabs and connect small leads
>     to an external battery keeping the still working SRAM.
> 
>     This for example:
> 
>     https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&ved=2ahUKEwiDl_DKzZnwAhVdElkFHZaBCTsQFjABegQIAhAD&url=http%3A%2F%2Fworldphaco.com%2Fuploads%2FTEKTRONIX_2465b_OSCILLOSCOPE_CALIBRATION___REPOWERING_THE_DS1225.pdf&usg=AOvVaw1WP8nMcsFuEALX2uMw2rP1
>     <https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.google.com%2Furl%3Fsa%3Dt%26rct%3Dj%26q%3D%26esrc%3Ds%26source%3Dweb%26cd%3D%26ved%3D2ahUKEwiDl_DKzZnwAhVdElkFHZaBCTsQFjABegQIAhAD%26url%3Dhttp%253A%252F%252Fworldphaco.com%252Fuploads%252FTEKTRONIX_2465b_OSCILLOSCOPE_CALIBRATION___REPOWERING_THE_DS1225.pdf%26usg%3DAOvVaw1WP8nMcsFuEALX2uMw2rP1&data=04%7C01%7CPeter.Ullrich%40kapsch.net%7Ca0274962ed934dbc4e9708d908288bba%7C5f9ce5277e3e4e83a8a4b6c848f85ab5%7C1%7C1%7C637549792517077806%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=yRkTS7GyqaWRIcExGkwmVejxd4OUdd3JnLQ5uaLsP8w%3D&reserved=0>
> 
> 
>     Since my chip is a M48Z18-100PCI it does not have the same
>     potted packing of a genuine DS1225 (should it ??) so dremeling it
>     to reach the battery tabs would be quite hazardous..
> 
>      
> 
>     *So here is my question:*
> 
>     I'd like to build a small 28 pins 600mils DIP pcb
>     who would contain a 8Kx8 SRAM with battery controller IC
>     the same way the inside DS1225 does it:
> 
>     DS1218 and DS2064 are now obsolete ICs so this would not be a good
>     choice..
> 
>      
> 
>     A company called Glitch Works has this type of new substitute IC
>     available:
> 
>     https://www.tindie.com/products/glitchwrks/glitch-works-gw-1225-1-dallas-ds1225-replacement/
>     <https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.tindie.com%2Fproducts%2Fglitchwrks%2Fglitch-works-gw-1225-1-dallas-ds1225-replacement%2F&data=04%7C01%7CPeter.Ullrich%40kapsch.net%7Ca0274962ed934dbc4e9708d908288bba%7C5f9ce5277e3e4e83a8a4b6c848f85ab5%7C1%7C1%7C637549792517077806%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=rucOTTgO5gSJ1wlmNte3NrRIO2kN5Kog%2B7O9Y1M3Lfo%3D&reserved=0>
> 
>     But for me $51.00US including shipping to Canada is too expensive..
> 
>     But the idea of a small 28 pins DIP pcb module is a good one..
>     Building it would be fun too !
> 
>     I’m not an engineer and cannot figure out the DS1225 read/write
>     needs to be taken care of
>     choosing the right components. Any 8Kx8 SRAM with a 100ns
>     acquisition should do
>     but the choice of a good battery controller IC and the adequate
>     connections between both IC’s
>     and the 28 DIP pins to behave exactly like a M48Z18 or DS1225
>     exceeds my knowledge..
> 
>     Can you help with some possible IC’s and some easy wirings linking
>     them ?
> 
>     Many thanks !
> 
>      
> 
>      
> 
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> -- 
> 
> Confucius says: Man with problem who thinks solution is regular
> expression now has two problems.
> 
>     */s/two/many/*
> 
> 
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