Re: [N8VEM-S100:7702] SD Card Questions

Hi Alex,

then I think my second point becomes the relevant point.

Would it be possible to develop a discrete logic replacement circuit to achieve higher performance and allow continued use of CF media and the current CF media

imaging process with cpmtools.

regards

David

On Thursday, October 1, 2015 at 4:13:20 PM UTC+1, Alexander wrote:

David,

I assume that John is thinking that the bottleneck is the Intel PPI (8255A) interface chip, and not the media. The maximum throughput for this chip is far lower than the theoretical maximums for even basic SD/MMC cards.

- Alex

On Thu, Oct 1, 2015 at 11:05 AM, 'David Fry' via N8VEM-S100 <n8ve...@googlegroups.com> wrote:
John,

Before you develop another flash memory card have you tried using any of the higher end x266 or better CF cards that are designed for SLR photography to see if performance picks up.
I’ve looked at the Kingston website for the basic (White Lilly) 4GB cards and they don’t specify a speed which makes me suspect that they are slow cards,
Whereas the x266 CF card is specified at 40 – 45MB/Sec, and the x600 CF card is specified at 90MB/Sec.

If it does turn out that the 8255 is the bottleneck would it not be worth developing a discrete logic replacement to try and maintain broad compatibility with the existing software (monitor)
Base and CF card imaging process (cpmtools)

Maybe others could comment on the differences between CF media and SD card media in terms of disk layout etc...

Regards

David Fry

From: n8ve...@googlegroups.com [mailto:n8vem...@googlegroups.com] On Behalf Of John Monahan
Sent: 01 October 2015 13:13
To: n8ve...@googlegroups.com
Subject: [N8VEM-S100:7701] SD Card Questions

Hi Josh,
I am toying with the idea of building a dual Micro SD card S100 board. I’m finding that the bottleneck in my 80386/80486 prototypes for MSDOS etc. is the 8255A driven dual IDE/CF board. Did you get the SD card working with CP/M on your 8080 board. Any idea how “fast” it is relative to a CF card for data access. I’m worried the interface is in fact slower that an 8255A. Perhaps a large Flash RAM board would be a better approach. What do you think.

John

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