new storage interface

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Karl Albert Brokstad

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Jul 26, 2021, 2:02:09 PMJul 26
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Hi
I have just received a new SD to IDE interface.
This works as an direct replacement for the CF adapter on my storage modules.
I have tested it briefly and it appear to be working well.
The SD cards are reported with correct size in ROMWBW.
And as SD cards are more well behaved than CF cards this is very promising.
Karl

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Screen Shot 2021-07-26 at 19.38.33.png

Matthew Barrick

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Jul 26, 2021, 4:16:31 PMJul 26
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Did you test it with SDHC/larger cards? Curious as to how big it will work with.

Karl A. Brokstad

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Jul 26, 2021, 4:25:57 PMJul 26
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I have briefly tested with cards up to 64gb, but I think Romwbw/ cpm will only allow 16 partitions at 8 mb.

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On 26 Jul 2021, at 22:16, Matthew Barrick <dna...@gmail.com> wrote:

Did you test it with SDHC/larger cards? Curious as to how big it will work with.
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Wayne Warthen

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Jul 26, 2021, 4:59:06 PMJul 26
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On Monday, July 26, 2021 at 1:25:57 PM UTC-7 Karl Albert Brokstad wrote:
I have briefly tested with cards up to 64gb, but I think Romwbw/ cpm will only allow 16 partitions at 8 mb.

Probably a good opportunity to clarify the maximum storage supported by RomWBW.

Actually, the RomWBW storage drivers support up to 20GB. 😊  However, there are other constraints that are involved in real use.

The RomWBW OSes (CP/M, ZSDOS, etc.) handle a maximum of 256 8MB slices.  This means that a single storage device could have as much as 2GB of CP/M storage.  However, it is possible to place a FAT12/16/32 partition after the CP/M storage which could easily occupy the full remainder of the storage.

I think that Karl is referring to yet another constraint.  Specifically, the CP/M and workalike OSes use a maximum of 16 drive letters (A-P) which matches Karl's comments.  This is a constraint of the OSes, so nothing RomWBW can really do about it.  With one slice per drive letter, this comes out to a maximum of 128MB of CP/M storage available at one point.  Accessing the other slices of the 256 requires using the ASSIGN command to remap the drive letters as desired.

I know folks will quickly remind me that some CP/M replacement OSes (e.g., ZSDOS) do support a single drive letter with more than 8MB.  However, RomWBW wishes to ensure compatibility of the underlying storage across all the OSes, so it uses the lowest common denominator which is 8MB.

Clear as mud?

-Wayne

PauldB

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Jul 28, 2021, 11:47:30 AMJul 28
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Hi Karl,

That's a nice and easy way to get an SD card interface on RC2014!

I have one of those IDE-to-SD card adapters but haven't been able to use it because I haven't found a source for the 44 pin female connector. Where did you find the connector?

Paul

Karl A. Brokstad

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Jul 28, 2021, 2:06:41 PMJul 28
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Hi Paul 
I got them on eBay. 
44pin 2inch female IDE header 

 Steve Cousins has implemented SD interface using i2c.

Karl

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On 28 Jul 2021, at 17:47, PauldB <pakt...@gmail.com> wrote:


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PauldB

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Jul 28, 2021, 4:50:20 PMJul 28
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Not easy to find this 2.0mm pitch female header, but did finally find it on ebay.

In case anyone else is looking for this connector, this is the one I found (super long url so I won't post it):

Seller: win-hezhu
Item description: 10x Pitch 2.0mm 2mm 2x22 Pin 44 Pin Female Double Row Straight Pin Header Strip

Bill Shen

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Jul 28, 2021, 7:19:16 PMJul 28
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With the standard 1.6mm thick pc board, you can slide the 2x22 2mm male header over the corresponding 2x22 contact fingers and achieve reliable connections without soldering the pins.  I have many boards working for months with such temporary arrangement.
  Bill

PauldB

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Jul 29, 2021, 10:02:35 AMJul 29
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Thanks, Bill. I'll give that a try.

Paul

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