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Old 23rd Jun 2024, 7:49 am   #1
netdudeuk
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Default 2102 RAM speeds

Hi

I’m looking for some 2102-2s for my Triton build. They seem to the 250ns version. There are plenty of 2102s on eBay but they all seem to be the MM2102AN-4L (450 ns) or 2102AN (350ns) versions. How likely are they to still be fast enough for the video display application ?

Thanks
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Old 23rd Jun 2024, 10:13 am   #2
Phil__G
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Default Re: 2102 RAM speeds

Tim or Ian L would know for sure, I would expect 450s to be fine - the Nascom-1 memory-mapped display used 2102 450s, and my Elekterminal (which uses the same Thompson CSF chip as the Triton) uses 2102 450s.
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Old 23rd Jun 2024, 4:12 pm   #3
Mark1960
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Default Re: 2102 RAM speeds

Intel 2102-2 was 650 ns. You need to refer to manufacturers data sheets to determine access speed from part numbers as they don’t always translate direct to access times.

https://archive.org/details/bitsaver...e/n55/mode/2up
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Old 24th Jun 2024, 2:05 pm   #4
ortek_service
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Default Re: 2102 RAM speeds

Yes, and on Intel A-suffix devices, the extra -n numbers represent different speeds to that on non A-suffix ones.
There is conflicting info on the 'net (Inc. a Wikipedia page on it) on the Triton 8080's Clock speed with both 0.8MHz or the full 2MHz clock-rate being mentioned.
However, if an 8080 instruction takes at least 4 clock cycles, then 650ns should probably be plenty fast enough (IIRC 450ns devices were used in the ZX81 with a more-efficient faster 3.25MHz Z80)
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Old 24th Jun 2024, 6:20 pm   #5
netdudeuk
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Default Re: 2102 RAM speeds

Quote:
Originally Posted by Mark1960 View Post
Intel 2102-2 was 650 ns. You need to refer to manufacturers data sheets to determine access speed from part numbers as they don’t always translate direct to access times.

https://archive.org/details/bitsaver...e/n55/mode/2up
Thanks Mark. I've got my own Intel data sheet

That doesn't even show 650ns parts and the ones with the 2 suffix are both 250ns. I''ve got the PDF and I'd upload it if I could. I'm not sure where I obtained it from.

Regardless, it looks like the 450ns parts should be more than enough, Thanks to everyone else too for their comments.
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Old 24th Jun 2024, 6:50 pm   #6
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Default Re: 2102 RAM speeds

I used original Nat Semi MM2102AN-2L parts which I was lucky enough to source on my repro. I do have some -4 which I believe are slower but, never tried them - I am hoping to use them on my original board as that came denuded of many chips - of course for those who don't know they are the 7 video chips so not so affected by the CPU speed anyway unless you are doing the direct memory mapped screen access.

My original board has the original 7.2Mhz crystal on board. Once it is working I plan to uprate my replica to the 18Mhz which was a common upgrade - hence the confusion on the processor speed as indeed there was a double speed upgrade that came out later - the 7.2 firmware was patched to handle that.
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Old 25th Jun 2024, 1:20 am   #7
ortek_service
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Default Re: 2102 RAM speeds

Quote:
Originally Posted by netdudeuk View Post
>>
I've got the PDF and I'd upload it if I could. I'm not sure where I obtained it from.
>>
Well to upload the pdf, you should just need to click on the 'Paperclip' attachment button, and in the pop-up window click on a 'Choose File' button and navigate to the file.
Finally, you have to remember to click on 'Upload' to attach the selected files before closing the pop-up window.
PDF's upto 4MB are allowed, but I think these (I know images are) may sometimes be compressed down to a smaller size (even if below this), so Zipping PDF-up to preserve original size and attaching that instead / as well, is sometimes useful.
Doing this / with images also saves having to open the ZIP, to preview them.

It may be that as a relatively-new user, you may have to wait until attachments are checked for first few posts, but should be OK after a while / made 10+ as required to access modern-Technology area.
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Old 25th Jun 2024, 7:16 am   #8
netdudeuk
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Default Re: 2102 RAM speeds

Here's my own 2102 data sheet.

Thanks.
Attached Files
File Type: pdf 2102A.pdf (130.8 KB, 81 views)
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Old 25th Jun 2024, 10:08 am   #9
Phil__G
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Default Re: 2102 RAM speeds

Somewhere I have my original 1978 paper 2102 datasheet, its blue IIRC. I'll have a dig.
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Old 25th Jun 2024, 10:44 am   #10
Phil__G
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Default Re: 2102 RAM speeds

Well, seems I remembered the 'blue' part but its an Archer datasheet:

Also, if its of interest for the Triton, I've an original paper Thompson CSF 96364 datasheet - its actually a photocopy, they all were, but its a 1st copy rubber-stamped by Thompson CSF
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File Type: pdf 2102_datasheet.pdf (1.34 MB, 75 views)
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Old 25th Jun 2024, 10:47 am   #11
ortek_service
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Default Re: 2102 RAM speeds

Quote:
Originally Posted by netdudeuk View Post
Quote:
Originally Posted by Mark1960 View Post
Intel 2102-2 was 650 ns. You need to refer to manufacturers data sheets to determine access speed from part numbers as they don’t always translate direct to access times.

https://archive.org/details/bitsaver...e/n55/mode/2up
Thanks Mark. I've got my own Intel data sheet

That doesn't even show 650ns parts and the ones with the 2 suffix are both 250ns. I''ve got the PDF and I'd upload it if I could. I'm not sure where I obtained it from.

Regardless, it looks like the 450ns parts should be more than enough, Thanks to everyone else too for their comments.
Quote:
Originally Posted by netdudeuk View Post
Here's my own 2102 data sheet.

Thanks.
Thanks for adding your datasheet (which originated from a scan by the CapsXpert system - that had been free on the 'net at one point. So no-doubt someone had preserved a copy of that one and put it on a website).

I see it is for the (faster) A-suffix version, where I noted earlier the -suffix numbers (as well as the default speed without any of these) are different (and a bit more logical correspondence to access-speeds on the A-suffix versions.
Although there is also a rarer M2102A type, that is slower-rated to work over the full Mil-Spec temperature range.

Whereas Mark had linked to a scan of the Intel 1975 Data Catalog, that contained both the original 2102 as well as the later, faster, 2102A and also the M2102A. Plus it also contained a single-page summary of the speeds for all of these.
And I've extracted and attached a copy of that summary - along with the 2102(-1,-2,-8) & 2102A(L)(-2,-4) + M2102A(-4,-6) datasheets - for ease of reference.


It would have been a bit clearer if Intel had always put an access-speed suffix on these (rather than default version with no suffix having access-time in the middle, and suffixes only being used for the faster and slower versions).

But as all A-suffix versions are faster than the original 2102-2 (650ns), 2102 (1000ns) or 2102-8 (1500ns), then any of these should be a suitable replacement for those particular 2102 versions (And the 2102A is also faster than original fastest 2102-1 (500ns) - Unless using the slowest M2102A-6 (650ns) Mil-spec temperature range one).

Last edited by ortek_service; 25th Jun 2024 at 11:04 am.
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