VOGONS


Using old com ports as usb ports.

Topic actions

First post, by Sphere478

User metadata
Rank Oldbie
Rank
Oldbie

Hey, I was reading around and I found a site (then promptly lost it 🤣) but it’s alright cause it was pretty vague. Anyway there was this idea that since no one uses com ports anymore these days and that they are similar and there are bridge chips that it would be possible to use your com ports as usb ports, though likely very slow ones.

I was interested in learning more about this. Does anyone have any experience with this? I think it would be cool to plug into the com ports, and pop out of the back of the computer as usb ports

🖥Craziest socket 7 build on a 430tx chipset
🖥Dual socket 7 build

Reply 2 of 21, by darry

User metadata
Rank l33t
Rank
l33t
Sphere478 wrote on 2021-01-19, 04:42:

Hey, I was reading around and I found a site (then promptly lost it 🤣) but it’s alright cause it was pretty vague. Anyway there was this idea that since no one uses com ports anymore these days and that they are similar and there are bridge chips that it would be possible to use your com ports as usb ports, though likely very slow ones.

I was interested in learning more about this. Does anyone have any experience with this? I think it would be cool to plug into the com ports, and pop out of the back of the computer as usb ports

Bridge chips that allow running a COM port off a computer's USB port are common and require only a driver for the host OS .

AFAIK, bridge chips that work in the opposite direction (add a USB port through a computer's existing COM port) do not exist and, if they did, would require a custom USB stack on the host OS side, which would have to be written from scratch . And assuming a device of this kind was made and software written for it, the 15KB/sec (and many older COM port UART chips won't even handle a fraction of that) or so max speed of a COM port would make it practically useless, IMHO .

Reply 3 of 21, by mr.cat

User metadata
Rank Member
Rank
Member
darry wrote on 2021-01-19, 05:58:

And assuming a device of this kind was made and software written for it, the 15KB/sec (and many older COM port UART chips won't even handle a fraction of that) or so max speed of a COM port would make it practically useless, IMHO .

Impractically there are some use cases where even lower bitrates would be satisfactory. That's stepping into a territory better served by something like a very low-powered microcontroller, of course.
But these builders, they tend to be quite an imaginative lot, so maybe there's *something*...

A more interesting option might be to use SCSI if that's available.

Reply 4 of 21, by Sphere478

User metadata
Rank Oldbie
Rank
Oldbie
darry wrote on 2021-01-19, 05:58:
Sphere478 wrote on 2021-01-19, 04:42:

Hey, I was reading around and I found a site (then promptly lost it 🤣) but it’s alright cause it was pretty vague. Anyway there was this idea that since no one uses com ports anymore these days and that they are similar and there are bridge chips that it would be possible to use your com ports as usb ports, though likely very slow ones.

I was interested in learning more about this. Does anyone have any experience with this? I think it would be cool to plug into the com ports, and pop out of the back of the computer as usb ports

Bridge chips that allow running a COM port off a computer's USB port are common and require only a driver for the host OS .

AFAIK, bridge chips that work in the opposite direction (add a USB port through a computer's existing COM port) do not exist and, if they did, would require a custom USB stack on the host OS side, which would have to be written from scratch . And assuming a device of this kind was made and software written for it, the 15KB/sec (and many older COM port UART chips won't even handle a fraction of that) or so max speed of a COM port would make it practically useless, IMHO .

Yeah, I was figuring a custom driver would be in order.

But even a low speed usb port would definitely be handy. Especially on systems that don’t have usb probably still fast enough for mice and keyboards

Speaking of, has anyone found a usb isa card yet that works with “not just a thumb drive”

mr.cat wrote on 2021-01-19, 06:22:
Impractically there are some use cases where even lower bitrates would be satisfactory. That's stepping into a territory better […]
Show full quote
darry wrote on 2021-01-19, 05:58:

And assuming a device of this kind was made and software written for it, the 15KB/sec (and many older COM port UART chips won't even handle a fraction of that) or so max speed of a COM port would make it practically useless, IMHO .

Impractically there are some use cases where even lower bitrates would be satisfactory. That's stepping into a territory better served by something like a very low-powered microcontroller, of course.
But these builders, they tend to be quite an imaginative lot, so maybe there's *something*...

A more interesting option might be to use SCSI if that's available.

what do you mean about the scsi? Can you explain?

🖥Craziest socket 7 build on a 430tx chipset
🖥Dual socket 7 build

Reply 5 of 21, by mr.cat

User metadata
Rank Member
Rank
Member

what do you mean about the scsi? Can you explain?

SCSI has the bandwidth to do some more practical things. I was thinking something like these babies (quite costly things!):
http://www.codesrc.com/mediawiki/index.php/SCSI2SD

Last edited by mr.cat on 2021-01-19, 08:27. Edited 1 time in total.

Reply 6 of 21, by Jo22

User metadata
Rank l33t++
Rank
l33t++
Caluser2000 wrote on 2021-01-19, 05:18:

Com ports are still used in idustrial equipment.

And by electronic hobbyists who like to bit-bang. 😀

"Time, it seems, doesn't flow. For some it's fast, for some it's slow.
In what to one race is no time at all, another race can rise and fall..." - The Minstrel

//My video channel//

Reply 7 of 21, by Sphere478

User metadata
Rank Oldbie
Rank
Oldbie
mr.cat wrote on 2021-01-19, 07:08:

what do you mean about the scsi? Can you explain?

SCSI has the bandwidth to do some more practical things. I was thinking something like these babies (quite costly things!):
http://www.codesrc.com/mediawiki/index.php/SCSI2SD

that’s kinda neat. Looks like a scsi to sd card adapter? What is the little usb port for? Programming it?

🖥Craziest socket 7 build on a 430tx chipset
🖥Dual socket 7 build

Reply 8 of 21, by mr.cat

User metadata
Rank Member
Rank
Member
Sphere478 wrote on 2021-01-19, 18:24:
mr.cat wrote on 2021-01-19, 07:08:

what do you mean about the scsi? Can you explain?

SCSI has the bandwidth to do some more practical things. I was thinking something like these babies (quite costly things!):
http://www.codesrc.com/mediawiki/index.php/SCSI2SD

that’s kinda neat. Looks like a scsi to sd card adapter? What is the little usb port for? Programming it?

It's for updating firmware. I don't think you can you use it to write any actual data.
In the 90s many UNIX workstations used SCSI, so this is a perfect solution for them.

Reply 9 of 21, by adalbert

User metadata
Rank Member
Rank
Member

Raspberry Pi Zero costs 5$ and has USB port, you can pair it with RS232 to TTL converter and connect it to PC... then you can do anything you want with scripts/software (which obviously would be the most difficult part).

Reply 10 of 21, by Errius

User metadata
Rank l33t
Rank
l33t

Computers are still made with serial ports but not parallel ports. Does nobody use those anymore?

“I like to dissect PCs. Don't you know I'm utterly insane?"

Reply 11 of 21, by Sphere478

User metadata
Rank Oldbie
Rank
Oldbie
Errius wrote on 2021-01-20, 05:02:

Computers are still made with serial ports but not parallel ports. Does nobody use those anymore?

i haven’t in ages

🖥Craziest socket 7 build on a 430tx chipset
🖥Dual socket 7 build

Reply 12 of 21, by Pierre32

User metadata
Rank Oldbie
Rank
Oldbie
Errius wrote on 2021-01-20, 05:02:

Computers are still made with serial ports but not parallel ports. Does nobody use those anymore?

Weirdly I picked up an old laptop the other week that has a parallel port, but no serial port! (Toshiba Tecra M3).

I still use parallel ports, because I have a parallel CF reader. Pretty handy for moving files between different era machines in a pinch. Parallel Port Compact Flash card reader for very old PCs

Reply 13 of 21, by Sphere478

User metadata
Rank Oldbie
Rank
Oldbie
Pierre32 wrote on 2021-01-20, 06:59:
Errius wrote on 2021-01-20, 05:02:

Computers are still made with serial ports but not parallel ports. Does nobody use those anymore?

Weirdly I picked up an old laptop the other week that has a parallel port, but no serial port! (Toshiba Tecra M3).

I still use parallel ports, because I have a parallel CF reader. Pretty handy for moving files between different era machines in a pinch. Parallel Port Compact Flash card reader for very old PCs

neat! Don’t I remember parallel hard drives were a thing also? Can you boot to them?

🖥Craziest socket 7 build on a 430tx chipset
🖥Dual socket 7 build

Reply 15 of 21, by Error 0x7CF

User metadata
Rank Member
Rank
Member

You can "boot" Windows 3.11 on one if you put DOS on the main bootable drive and Windows on the external.
Might be able to do something similar with 9x but I'm not positive.

Old precedes antique.

Reply 16 of 21, by Pierre32

User metadata
Rank Oldbie
Rank
Oldbie
Error 0x7CF wrote on 2021-01-20, 08:18:

You can "boot" Windows 3.11 on one if you put DOS on the main bootable drive and Windows on the external.
Might be able to do something similar with 9x but I'm not positive.

Hmm. "Installing Windows 3.11 to a parallel port CompactFlash card" is a Youtube video that hasn't been done yet 😁

Reply 17 of 21, by Sphere478

User metadata
Rank Oldbie
Rank
Oldbie
Error 0x7CF wrote on 2021-01-20, 08:18:

You can "boot" Windows 3.11 on one if you put DOS on the main bootable drive and Windows on the external.
Might be able to do something similar with 9x but I'm not positive.

That makes sense. You’d basically be using dos as a boot loader

Yes. Someone needs to make a video 🤣

🖥Craziest socket 7 build on a 430tx chipset
🖥Dual socket 7 build

Reply 18 of 21, by Errius

User metadata
Rank l33t
Rank
l33t

Sorry for dragging this off topic

How do PCI/PCIe parallel port cards work? Do they require special drivers? Can you use them in DOS?

“I like to dissect PCs. Don't you know I'm utterly insane?"

Reply 19 of 21, by Jo22

User metadata
Rank l33t++
Rank
l33t++
Errius wrote on 2021-01-22, 03:06:

Sorry for dragging this off topic

How do PCI/PCIe parallel port cards work? Do they require special drivers? Can you use them in DOS?

Yes, I think. PCI-based LPT ports require special drivers that make the legacy ports appear ($3BC, $378, $278).
Otherwise, DOS programs themselves have to be modified, I'm afraid.

Edit : PCI-based LPT ports use $DF00-$DF07, I think.
Edit: Marked addresses as hex ($) to avoid confusion.

"Time, it seems, doesn't flow. For some it's fast, for some it's slow.
In what to one race is no time at all, another race can rise and fall..." - The Minstrel

//My video channel//