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Questions about Serial ports

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abruno17

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This is a bit of a dumb question but I thought I’d ask to settle my curiosity. Could I transfer files from a usb stick through an adapter to the serial port and treat it as an external drive of sorts to write floppies?
 
No, since an USB stick is dumb. It has no server running on it that could serve you files over serial.
 
Some development boards for USB mass storage prototyping have serial ports available which sometimes was replicated on the production hardware. I vaguely remember someone doing a serial port terminal into a SD card or USB flash drive controller. It has been more than a decade and I can't find it now so my fallible memory must suffice. Whether any of these could be turned into a product that meets the OP requirements without years of work is beyond me.

Using a HP-50g calculator as a serial port adapter for SD cards would seem excessive though it is a proof of concept. It is portable and 2GB should handle a reasonable number of transfers for a floppy based system.

What are you planning on using on the computer to acquire these files from the serial port? If the system already has a hard drive, transferring files to the hard drive in the usual manner seems easier.
 
abruno17 said:
Could I transfer files from a usb stick through an adapter to the serial port and treat it as an external drive of sorts to write floppies?
Click to expand...
Yes, but performance would be abysmal. Additionally, I am not aware of any standardized protocol to do so on the PC. Custom protocols do exist, e.g. Norton Commander or INTERLNK/INTERSVR, but I don't know whether they have been documented well enough.

Therefore, you need to invent both sides of the equation: A controller speaking both "USB mass storage class" and serial, and PC software implementing the "external drive" using the serial port. It is lots of work, but code for all parts is commonly available. Good luck. :)

I have done something like this before in a CP/M bring-up: Before I had actual storage support working, I used a small self-written Linux terminal program (think "picocom") which intercepted special escape sequences to send and receive sectors from image files. A matching driver in the CP/M BIOS made those files available to CP/M. Performance was somewhat acceptable, but it was never fully reliable. But it worked well enough to develop and test the true storage driver.
 
Serial to USB cables do exist, but they're designed for printers (and maybe a few other devices), but not mass storage. The popular method of transferring files via serial ports would be a laplink cable between two computers (both with serial ports). It's pretty slow, and parallel port transfer is quicker.
 
abruno17 said:
This is a bit of a dumb question but I thought I’d ask to settle my curiosity. Could I transfer files from a usb stick through an adapter to the serial port and treat it as an external drive of sorts to write floppies?
Click to expand...
I think a GoTek would be the best solution. All PCs support at least one floppy. Make images of the floppy on a PC, copy the images to the USB stick and then do a disk copy to get to a real floppy. If you want to copy individual files then perhaps load some DOS TCPIP software, create a SLIP or PPP connection via a serial port. I think the KA9Q software is still around but other solutions exist.
 
Svenska said:
Yes, but performance would be abysmal. Additionally, I am not aware of any standardized protocol to do so on the PC. Custom protocols do exist, e.g. Norton Commander or INTERLNK/INTERSVR, but I don't know whether they have been documented well enough.

Therefore, you need to invent both sides of the equation: A controller speaking both "USB mass storage class" and serial, and PC software implementing the "external drive" using the serial port. It is lots of work, but code for all parts is commonly available. Good luck. :)

I have done something like this before in a CP/M bring-up: Before I had actual storage support working, I used a small self-written Linux terminal program (think "picocom") which intercepted special escape sequences to send and receive sectors from image files. A matching driver in the CP/M BIOS made those files available to CP/M. Performance was somewhat acceptable, but it was never fully reliable. But it worked well enough to develop and test the true storage driver.
Click to expand...
Whilst its not the fastest you can you Kermit to transfer files. I think you can use kermit-2-kermit connections....
 
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