Dallas DS1245Y

[Phil__G]

Hi chaps, has anyone bought any recently that work OK at least for 64k, and can recommend a source, PM links please since we don't want to cause upset
Ta - Phil

[Keith956]

I've got a 1225Y, is that any use? Else Mouser sell them (they are not cheap!).

[Phil__G]

Thanks Keith, sorry no 1225 is only 8k. There are plenty of 1245Y's advertised but they ALL appear to be blacktopped so you just dont know what you're buying

[Roninfourseven]

Does the scenario require a brand new device or could you open it up and connect a battery externally?

[Mark1960]

I have just completed a pcb layout for a ram adapter using either a 32 pin dip or smd ram, ds1210, ds1218, ds1312 or bq2201 and one or two CR1025. I’ll be sending the gerbers to JLCPCB later today. It should work with AS6C1008 or similar 0.6” wide ram.

Using 1.27mm pitch pin headers with alternate pins removed to plug into a standard or turned pin 0.6” wide socket.

I can send you the gerbers, but probably best to wait until I test it myself first.

[Realtime]

Originally Posted by Roninfourseven

Does the scenario require a brand new device or could you open it up and connect a battery externally?

Here's one I did about 18 months ago. When you take the plasic cover off you can see the outline of the battery. It's potted-in so I used an old soldering iron bit on a low temperature to remove the potting and eventually the old battery. The battery hole is 14mm diameter and 2.5mm deep, so with a bit of padding it could host a CR1220 as a replacement.

[Phil__G]

Originally Posted by Roninfourseven

...could you open it up and connect a battery externally?

Originally Posted by Realtime

Here's one I did about 18 months ago.

Ah thats where I went wrong, after watching a Youtube vid I bought a diamond hole saw bit specially for the job but didnt have any success in 3 or 4 test chips (scrap 8k ones), I didnt realise the epoxy would melt! Your chip looks like a blacktopped China special, freshly printed

Originally Posted by Mark1960

I have just completed a pcb layout for a ram adapter using either a 32 pin dip or smd ram

That sounds ideal Mark, AS6C1008's are really cheap & readily available.

I tried FRAM some time back, it worked fine on the PICL but not at all on the RC2014 with its 7Mhz clock, or the Southern Cross Z80 at 4Mhz.
Theres a lot of talk of MRAM now but its very expensive as yet.

What I find odd is that there's no 'official' solution - these NVRAM chips are in loads of 30+ year-old equipment but there doesnt appear to be a current, pin-compatible commercial replacement, resulting in a lot of DIY bodges (like mine!) documented on the net

Somewhere I've a genuine AS6C4008 512k x 8 PDIP cmos sram intended for my "SC/MP disk drive" when I get a round tuit
Sadly the hobbyists favourite form factor PDIP is disappearing fast.

Meanwhile there are a lot of DS1245Y's advertised, it would be great if someone had found a source of good ones!

[ortek_service]

Yes, I completely disassembled a (rather-faulty, that kept corrupting other memory location when writing to different ones - but was retaining contents) one using a Temperature-controlled soldering iron to gouge into the Epoxy, which causes it to crumble-away into powder.
This works better than just side-cutters / chiselling away, as easier to remove small amount around the potted-parts, with minimal damage.

Inside was just a thin PCB, with an SMD TSSOP SRAM (Can't recall if there was a readable part number on it), a Dallas DIL8! (but legs bent for SMD) package backup-battery controller and the small Lithium cell.


According to Analog Devices, who bought Maxim-Dallas, this part is still in production in 70/85/100/120ns speed-grades etc. As well as Optional ±5% VCC operating range (DS1245AB) and -40/+85C Industrial-Temperature range *Std. are 0/+70C) versions of some of these.
Plus an SMD version, with a snap-on DS9034PC PowerCap replaceable battery module
https://www.analog.com/en/products/ds1245y.html
- But Manufacturer's standard 1000+ price is listed as $33!

Digikey/ Mouser / Farnell do also stock it at 1+ quantities, with quite a wide-variation in price (Digikey cheapest at £43+VAT), whereas RS no longer stock it.
Any of these much-cheaper than this, on eBay etc, you'd expect to be just old stock (Not uncommon to see 2004 / 2008 etc ones) / previously-used (so 'Freshness seal' hold-off disconnect of battery when new may no-longer be present, thereby draining battery faster). So if they are being faked, then presumably just a similar smaller-capacity one that's been re-marked.

So maybe owners of old Test-equipment with these in, are just buying brand-new ones - Getting the Cal. etc. data out of the old one (especially once battery has gone flat!) is probably more of an issue.

Ironically, for the outrageous-price these cost, it does seem surprising that some other company can't make an equivalent compatible one as parts cost can't be more than a few £'s.

[Mark1960]

Attached schematic and layout of the adapter pcb.

I'll create some assembly instructions when I receive the boards.

[Keith956]

Originally Posted by Phil__G

Meanwhile there are a lot of DS1245Y's advertised, it would be great if someone had found a source of good ones!

Hi Phil, As before, Mouser stock them, at a price:

https://www.mouser.co.uk/c/?q=DS1245Y

[ortek_service]

Originally Posted by Keith956

Hi Phil, As before, Mouser stock them, at a price:

https://www.mouser.co.uk/c/?q=DS1245Y

Yes, just under £48 (+VAT) at Mouser for the cheapest (DS1245AB-70+) version, listed amongst those there.
But Digikey list many DS1245Y's, for a bit-cheaper £42(+VAT):
https://www.digikey.co.uk/en/products/filter/memory/memory/7...2aEY8gUa5SwABghtOkECELtLrXC50bBRdIA
With both giving free delivery on orders > £33, IIRC.

[Phil__G]

It sounds a lot, but I think back to the cost of my Nascom-1 16k RAM-A board and Buffer Board - well over £200 in 1980 !!! ...and not too reliable either!!!

[ortek_service]

Yes, even in the Mid-1980's, 128K RAM would generally cost > £50 (That with inflation, is far-more today).
It's just that when you're used to buying GByte DIMM's for a few pounds (Some used with 5yr warranty for only 10p from CeX!), then it doesn't seem very-good value in today's RAM cost-per-Byte prices.

Although it's not really the actual RAM in it that's costing a high-price, but you're paying a very-high price for the privilege of having it sealed with a small back-up cell in a module.

[flyingtech55]

RS seem to have them...not directly but they do have them on their website. As you say, not cheap. Around £27.00p


HTH


Tim(R)

[Phil__G]

Where Tim? the only DS1245Y that comes up for me on RS is marked "unavailable, no longer stocked"
https://uk.rs-online.com/web/p/nvram/1899196

[flyingtech55]

Phil


It was in the 'Show all NVRAM' button listing. It didn't say it was unavailable and even gave the price of £33. However, when I tried to put it in my basket it then said it was unavailable. The entry on the list has now changed to no longer available. Sorry to have given you incorrect information.


I know I got a new Dallas chip for my Tek 'scope from RS but that was a while ago.


Sorry again.


Good luck with your search.


Tim

[flyingtech55]

Seen them on DigiKey but as you say,not cheap.

[Phil__G]

No probs Tim, its a minefield out there
Phil

[ortek_service]

Originally Posted by flyingtech55

Seen them on DigiKey but as you say,not cheap.

Yes, and Digikey seemingly the cheapest for new ones, as I'd previously posted:

Originally Posted by ortek_service

>>
>>
But Digikey list many DS1245Y's, for a bit-cheaper £42(+VAT):
https://www.digikey.co.uk/en/products/filter/memory/memory/7...2aEY8gUa5SwABghtOkECELtLrXC50bBRdIA
With free delivery on orders > £33

An advantage at least of buying ones from there is that they are likely to be recent production/stock
- So should get at least 10yrs life out of them, not costing too much per year usage.
Whereas most of the (Genuine, not re-marked) ones that have come from sellers in China seem to be dated >15yrs ago
- So might not last too-long (even if unused, so battery 'freshness seal' not activated yet) before having to hack the top-off to replace battery.

But still cheapest to DIY your own (especially for >1off) equivalent, that should then be much-easier to replace the coin-cell on.

[Phil__G]

My ex-equipment ones arrived, they're genuine, they test ok on the TL866 and retain ok overnight on a nearly 30 year-old cell!
This is only hobby stuff, nothing important so this is good enough for me.
One day I'll need to dig the old cell out but I'll cross that bridge when I come to it