VOGONS


First post, by torindkflt

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This is more of an "I'm just curious how feasible this would be" thought, as opposed to an "I want to do this and need help" question.

Has anyone here experimented with finding a way to read SD memory cards via the parallel port on old PCs? I imagine it would be a good (albeit slow) way to move bulk files to and from vintage computers that lack USB and networking, provided you didn't use cards larger than 2GB or used an OS that recognizes FAT32.

There is some precedent...I found an old article from 2012 about a guy who did this very thing under Linux. The hardware aspect actually seems relatively straightforward...it's the software that appears to be the most time-consuming and difficult. The question would be, though, how easily such a concept could be applied to DOS and Win9x. The article I mentioned is at http://blog.vinu.co.in/2012/05/attempt-to-mou … nnected-at.html

Just a curiosity on my part, really.

Reply 1 of 18, by emosun

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There's essentially no reason to do this with the advent of CF to IDE adapters. You can just transfer files back and forth that way and have it be faster than parallel.

The only situation where this would apply is a machine that has no ide controller at all , but has a parallel port.

Also , they made parallel cd rom drives and zip drives. So buy an old paralell cd rom drive and swap in a cf card reader to it.

Reply 2 of 18, by torindkflt

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CF cards in an IDE adapter are not hot-swappable though. An SD card reader connected to the parallel port would be. Also, what if you want to copy data from the old computer to a newer one instead of the other way around? I know there are parallel port CD-ROM drives, but I don't think parallel-port CD-R drives exist, at least not ones that a 386 or earlier can run due to the lack of processing power. Parallel port Zip drives are an option, but again you're limited to at most 250MB (750MB parallel Zip drives never existed), where an SD card could do up to 2GB, or more if you have an OS that supports FAT32.

Again, this isn't something I want to actually do, I'm just curious about the feasability and logistics of it since it's proven possible under Linux.

Reply 3 of 18, by cyclone3d

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Well, if it is possible under Linux, it is possible under DOS/Windows.

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Reply 4 of 18, by emosun

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torindkflt wrote:

CF cards in an IDE adapter are not hot-swappable though.

Yeah they are , so long as the computer doesn't seek the drive while it's removed. few people realise you can unplug them so long as the machine doesn't know it's unplugged. then just plug it back in and wait a bit before you access it.

torindkflt wrote:

An SD card reader connected to the parallel port would be. Also, what if you want to copy data from the old computer to a newer one instead of the other way around? I know there are parallel port CD-ROM drives, but I don't think parallel-port CD-R drives exist, at least not ones that a 386 or earlier can run due to the lack of processing power. Parallel port Zip drives are an option, but again you're limited to at most 250MB (750MB parallel Zip drives never existed), where an SD card could do up to 2GB, or more if you have an OS that supports FAT32.

I already said put a cf adapter in a cd drive housing , or did you skim read and not catch that?

Reply 6 of 18, by lolo799

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Similar but for a different format, there have been Compact Flash card adapter for the parallel port sold at retail, like this one that i have, and with DOS drivers working on XT computers:

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Reply 7 of 18, by Ozzuneoj

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Wow Parallel port CF card reader... I could totally use one of those. I had somehow never thought of such a thing.

I just looked them up and I'm seeing a huge price variation and a lot of different models. Not many of them mention DOS though.

How likely is it that they all use generic parts and would all work with the same DOS drivers? I'd love to get one, but I'm not spending a whole bunch of money it, especially if I can't verify DOS compatibility.

EDIT: Also, the biggest question I have would be, what are the REAL system requirements for something like this under DOS?

https://www.ebay.com/itm/DATAFAB-Image-Reader … vUAAOSwwI1ahvqn

I see it lists a 486 33, DOS 5.0 and 8MB of RAM... for a card reader. Is it even remotely possible to attach something like this to a much older computer to transfer the contents of the hard drive? Like, an IBM 5150 for example? That's what I would mainly use something like this for... backing up "large" amounts of data from systems that are limited to floppy disks.

I also have a couple of Parallel port CD burners but I highly doubt they would work for such an old computer due to the complexity of burning data to a CD without it getting corrupt in the process.

Now for some blitting from the back buffer.

Reply 8 of 18, by lolo799

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I'm using mine on a XT with a 8088 cpu, 512k of RAM, DOS 5 and the parallel port of the Hercules compatible card.
That model you linked to is an earlier model but uses the same drivers, so it should work fine on your 5150.
No idea about the models from other brands, like SanDisk ImageMate for example, best way to try would be to find the drivers and see if they run on your machine.

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Reply 9 of 18, by Jepael

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torindkflt wrote:

This is more of an "I'm just curious how feasible this would be" thought, as opposed to an "I want to do this and need help" question.

I have been thinking about it. Requires LPT connector, 5V to 3.3V level translator, external 5V supply input, 3.3V regulator and of course the SD card socket, so the hardware is very simple.

torindkflt wrote:

Has anyone here experimented with finding a way to read SD memory cards via the parallel port on old PCs? I imagine it would be a good (albeit slow) way to move bulk files to and from vintage computers that lack USB and networking, provided you didn't use cards larger than 2GB or used an OS that recognizes FAT32.

The most simple way is to use the SD card in the 1-bit SPI bus mode instead of the native 4-bit SD mode. Many microcontroller projects do this. On PC, it would be quite slow to bit-bang the SPI bus. Transmitting bits is just a matter of setting data output bit, toggling clock bit, reading data input bit, toggling clock bit, for all the data bits that need to be transferred. The bits are framed into bytes of 8 bits and messages of known lengths separated by the usage of chip select line. Another option is to try having a microcontroller between parallel port and SD card to allow for protocol conversion so multiple bits are transmitted per clock from the PC to microcontroller. Then it does not really matter if it is a SD card or USB stick connected as the storage media.

The biggest task is to write the PC software really. Obviously the PC knows nothing about SD cards being connected to LPT ports, so you can't boot from it, unless you have a boot rom that can present the SD interface as hard drive. The boot rom can be written of course, but then the problem is where to put the boot rom, perhaps program it into a flash chip and put it into a network card boot rom socket.

Another option is to make a DOS driver for the device so when driver is loaded in config.sys, it can access the SD card and present it as some drive, much like Zip drives or CD-ROM drives. The downside is you still can't boot from it, and you are limited to DOS understanding the partition table and file system on card (unless it's mounted as kind of image, which is also doable, but DOS 6.22 still can't use partitions larger than 2GB and drives larger than 8GB).

Third option is to just not let DOS know about the card at all, only write a software (menu driven like Norton Commander or the like) to browse the card and copy files to/from floppies or harddrives seen by DOS. Then it does not matter if the card is FAT32 or whatever as long as the copying software can understand it.

If the card is not on parallel port directly, but accessed through a microcontroller, it could be made to emulate DOS interlink through parallel or serial port so no DOS software would be needed.
Also the microcontroller could look like a BBS so file transfers with any modem terminal programs are possible, albeit at 115kbps only.

Reply 11 of 18, by Ozzuneoj

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lolo799 wrote:

I'm using mine on a XT with a 8088 cpu, 512k of RAM, DOS 5 and the parallel port of the Hercules compatible card.
That model you linked to is an earlier model but uses the same drivers, so it should work fine on your 5150.
No idea about the models from other brands, like SanDisk ImageMate for example, best way to try would be to find the drivers and see if they run on your machine.

Where could I find DOS drivers for these kinds of devices? My Google-Foo is failing me on this one.

Now for some blitting from the back buffer.

Reply 12 of 18, by Ozzuneoj

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Ozzuneoj wrote:
lolo799 wrote:

I'm using mine on a XT with a 8088 cpu, 512k of RAM, DOS 5 and the parallel port of the Hercules compatible card.
That model you linked to is an earlier model but uses the same drivers, so it should work fine on your 5150.
No idea about the models from other brands, like SanDisk ImageMate for example, best way to try would be to find the drivers and see if they run on your machine.

Where could I find DOS drivers for these kinds of devices? My Google-Foo is failing me on this one.

Anyone?

I got a generic CF to parallel reader for dirt cheap, and I'd like to see if any DOS drivers for similar devices work with this one.

Now for some blitting from the back buffer.

Reply 13 of 18, by Jo22

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Ozzuneoj wrote:

Anyone?

I got a generic CF to parallel reader for dirt cheap, and I'd like to see if any DOS drivers for similar devices work with this one.

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Good luck! 😀

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Reply 14 of 18, by SquallStrife

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derSammler wrote:

In case someone didn't notice: I attached a driver for that already a few posts ago. It also includes a readme-file telling you how to inferface the SD card to the parallel port.

Legend! 😀

People get philosophical about these types of solutions sometimes.

What I like about the parallel port SD option is that I don't need to get inside the computer to add it, and I can just build one unit to share between systems.

It annoys me that this forum occasionally gets into the "Why do X when we already have Y?" mindset. More choices to suite more usage scenarios is always a good thing.

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Reply 15 of 18, by Ozzuneoj

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Thanks for the link Jo22!

I can't believe it, but I was able to get this thing working in DOS with the drivers that came on the disk, even though it only mentions Windows 95 and NT support!

I'll post more info about this thing later, and I'll upload the driver too. It was incredibly easy to set up! I just plugged it into the Parallel port on my Everex EV659 Micro Enhancer Deluxe (EGA + Parallel card) that's in my IBM 5150 with a 286 upgrade card. I copied the CDISK.exe and CDISK.sys files from the install floppy to a blank 720k disk, ran CDISK.exe from the floppy on the IBM and it installed everything without any problems whatsoever. It works perfectly! I'm backing up all of the files from my DOS installation now, using the 16MB CF card that came with my first digital camera. I definitely need a 32MB card though, since the 16MB is actually smaller than the 20MB hard drive in my 5150, so it has to be done in two parts.

Anyway, I'm blown away by the simplicity of this... I thought it'd be a nightmare. I will make another thread about it later, with pics of the device, pics of the circuit board inside and the drivers I used.

Now for some blitting from the back buffer.

Reply 16 of 18, by Great Hierophant

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derSammler wrote:

In case someone didn't notice: I attached a driver for that already a few posts ago. It also includes a readme-file telling you how to inferface the SD card to the parallel port.

This would be a useful solution for owners of system with a crippled parallel port like the Tandy 1000s. With very few exceptions their built-in ports are always missing a signal necessary for things like Parallel Port Zip Drives, Ethernet adapters and CF readers and SCSI adapters. The driver does not appear to use any "missing signals" (except perhaps for the original Tandy 1000/A/HD).

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Reply 17 of 18, by 4xtx

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Great Hierophant wrote on 2018-03-18, 21:02:
derSammler wrote:

In case someone didn't notice: I attached a driver for that already a few posts ago. It also includes a readme-file telling you how to inferface the SD card to the parallel port.

This would be a useful solution for owners of system with a crippled parallel port like the Tandy 1000s. With very few exceptions their built-in ports are always missing a signal necessary for things like Parallel Port Zip Drives, Ethernet adapters and CF readers and SCSI adapters. The driver does not appear to use any "missing signals" (except perhaps for the original Tandy 1000/A/HD).

Interested to understand if you did a follow-up on this one?

I've got one of the very few use-cases that makes sense for a parallel port storage, so all this type of info is valuable 😀

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