Author Topic: Serial Port Shenanigans - ArcaOS 5.1.1 on a Lenovo M920t  (Read 936 times)

AmbulatoryCorpse

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Serial Port Shenanigans - ArcaOS 5.1.1 on a Lenovo M920t
« on: January 29, 2026, 12:09:46 pm »
Greetings all, new to the forums here but been in the computing game since I was in grade school a few decades ago.

Anyways, the hardware:
Lenovo M920t (i7-8700 3.2Ghz 16gb)
nvme 1tb drive
sata dvdr
external USR Sportster 33.6k

Burned my ArcaOS iso to phyical media and dropped it in the drive to partition then install - all good, mostly. Save there's no COM1 - instead I have a SERIAL_0 attached to the ISA bus. Right. Well at least it's got the right address and interrupt..

Anyway, since this is primarily for reasons of a nostalgia driven trip to the times of yore when I ran a WWIV 4.24 dial up BBS, I forge on and start playing with SIO v1, which bombs out and requires a little offline surgery of the config.sys to get the system running again. Okay, on to SIO v2. No physical com port at all, 4 uart dummies and 4 vmodems all appear per default settings for SIO though, so progress?

Okay, maybe I need the CSM on to make it play nice? Nope. Same status. Though I did discover that sometimes a cold boot can make it come up properly under SIO v2, but that's more a fluke then a norm.

Anyway, introduction and background out of the way... Anyone have some pointers on where to poke? At present I have no critical data on the system and can do a full system wipe if needed. Also have a couple empty pcie slots that could take a real serial card if there's one that's known to play nice?

Roderick Klein

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Re: Serial Port Shenanigans - ArcaOS 5.1.1 on a Lenovo M920t
« Reply #1 on: January 29, 2026, 12:35:58 pm »
Greetings all, new to the forums here but been in the computing game since I was in grade school a few decades ago.

Anyways, the hardware:
Lenovo M920t (i7-8700 3.2Ghz 16gb)
nvme 1tb drive
sata dvdr
external USR Sportster 33.6k

Burned my ArcaOS iso to phyical media and dropped it in the drive to partition then install - all good, mostly. Save there's no COM1 - instead I have a SERIAL_0 attached to the ISA bus. Right. Well at least it's got the right address and interrupt..

Anyway, since this is primarily for reasons of a nostalgia driven trip to the times of yore when I ran a WWIV 4.24 dial up BBS, I forge on and start playing with SIO v1, which bombs out and requires a little offline surgery of the config.sys to get the system running again. Okay, on to SIO v2. No physical com port at all, 4 uart dummies and 4 vmodems all appear per default settings for SIO though, so progress?

Okay, maybe I need the CSM on to make it play nice? Nope. Same status. Though I did discover that sometimes a cold boot can make it come up properly under SIO v2, but that's more a fluke then a norm.

Anyway, introduction and background out of the way... Anyone have some pointers on where to poke? At present I have no critical data on the system and can do a full system wipe if needed. Also have a couple empty pcie slots that could take a real serial card if there's one that's known to play nice?

Hello,

This is all from the top of my memory. You might be better of using the the PSCOM.SYS driver that comes with Arca Noae LLC. And not SIO2K drivers. Saldy the sources best I can recall are lost and the driver TRAPS are known. Try using PSCOMS.SYS with /F.

Serial_0 is correct. Type mode com1 on a CMD command line that will tell you if the serial port is working.
The CSM should not effect is a serial port works yes or no.

Best regards,
Roderick Klein

AmbulatoryCorpse

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Re: Serial Port Shenanigans - ArcaOS 5.1.1 on a Lenovo M920t
« Reply #2 on: January 29, 2026, 01:11:26 pm »
Indeed csm shouldn't affect, but it can mediate interrupts and I've seen stranger so it was worth poking.

I'm guessing it's less featured and doesn't do fossil?

Martin Iturbide

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Re: Serial Port Shenanigans - ArcaOS 5.1.1 on a Lenovo M920t
« Reply #3 on: January 29, 2026, 05:26:38 pm »
Hello AmbulatoryCorpse, welcome to the forum.

I always wanted to interact with someone that has more knowledge on OS/2 BBS, since I want to organize the stuff on HobbesArchive:
- http://hobbesarchive.com/?path=%2fpub%2fos2%2fserver%2fbbs
and
- http://hobbesarchive.com/?path=%2fpub%2fos2%2futil%2fBBS
...and even if it is possible document you journey to serial-model BBS in ArcaOS.

Like Roderick said, type "mode com1" on the command line to see what it shows and let us know.

Your "ThinkCentre M920 Tower" seems to have serial port, and the external USR Sportster 33.6k should work there. It is also interesting that this is the first ArcaOS UEFI installation that I seen with someone trying to make a serial modem to work on it.

Regards

« Last Edit: January 29, 2026, 07:56:51 pm by Martin Iturbide »
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AmbulatoryCorpse

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Re: Serial Port Shenanigans - ArcaOS 5.1.1 on a Lenovo M920t
« Reply #4 on: January 29, 2026, 09:07:37 pm »
Hello AmbulatoryCorpse, welcome to the forum.

Thanks much. Glad to make everyones acquaintance.


I always wanted to interact with someone that has more knowledge on OS/2 BBS, since I want to organize the stuff on HobbesArchive:
- http://hobbesarchive.com/?path=%2fpub%2fos2%2fserver%2fbbs
and
- http://hobbesarchive.com/?path=%2fpub%2fos2%2futil%2fBBS

Well I was dos, desqview, win 3.11 and win 95. Licensed and modified WWIV 4.23 - 4.24. Always wanted to try os/2, but couldn't get my youthful hands on a copy at the time.

Looks like a decent challenge - it would be nice to have a proper decent OS/2 BBS scene.


...and even if it is possible document you journey to serial-model BBS in ArcaOS.

I'm terrible about keeping notes - however having an open discussion and solving problems in a forum can definately contribute to having documentation - other peoples documentation efforts for thier BBS projects has informed some of this.


Like Roderick said, type "mode com1" on the command line to see what it shows and let us know.

Well that works in the 4os/2 window, so at least we're seeing that far. Gives me status for the port and lets me change speed, parity, etc.


Your "ThinkCentre M920 Tower" seems to have serial port, and the external USR Sportster 33.6k should work there. It is also interesting that this is the first ArcaOS UEFI installation that I seen with someone trying to make a serial modem to work on it.

Figured it should work, presuming AN has kept the driver stack up well enough. Getting basic WWIV 4.24 up on a physical com port should be easy enough presuming the intervening layers are working. Other things will require fossil support be set up at some layer or other - SIO just bakes it in as it's really built for BBS use.

I do have other modems to hook up and play with, so a multi-port rs232 serial interface is planned, perhaps even a multi modem pcie card.. dunno, very much a for fun project that
mostly gets prodded at night. I would love to have copies of BBS in general, WWIV in specific, file archives - have a few, always open to more.

The fun parts will be getting vmodems working beside the hardware in the multi node setup - since SIO looks abandoned and I don't see any modern replacements available in the os/2 world - though there are plenty on windows now - and figuring out an outbound telnet/rlogin gateway door.


Doug Clark

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Re: Serial Port Shenanigans - ArcaOS 5.1.1 on a Lenovo M920t
« Reply #5 on: February 01, 2026, 06:58:00 pm »
Quote
Also have a couple empty pcie slots that could take a real serial card if there's one that's known to play nice?

I am running a Quatech ESCLP-100  8 port PCI serial card on a Ryzen 5 / MSI system.  It requires a StarTec PEX1PCI1  PCI to PCIe adapter to work on my system.  Quatech has drivers for OS/2 and DOS - which are claimed to be drop-in replacements for the IBM Com drivers.  It works with a serial "keyboard" that I have, but does not work with my graphic/drawing tablets - I think the reason is the driver for the tablets expects a certain interrupt and address and with PCI/PCIe cards those are assigned at boot up.

The Quatech driver also requires CSM - it will load with pure UEFI but complains during boot up that it cannot communicate with the serial card.

I am not familiar with FOSSIL so cannot say what the relationship between FOSSIL and a COM port / COM port driver will be.

AmbulatoryCorpse

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Re: Serial Port Shenanigans - ArcaOS 5.1.1 on a Lenovo M920t
« Reply #6 on: February 02, 2026, 12:17:34 am »
am not familiar with FOSSIL so cannot say what the relationship between FOSSIL and a COM port / COM port driver will be.

Fossil is a standrd that developed in the BBS world to deal with multi port serial cards. It's a shim layer between the OS COM ports and multi-line BBS software. As long as one can identify the port and interrupt for a serial port the fossil driver can connect with it and provide communications via int14 for up to 254 serial ports.

When running DOS software, like WWIV, under OS/2 one has the option of loading a dos level fossil driver in the VDM. SIO provides an os/2 native and virtualized version of the X00 fossil driver that lives outside of the VDM space in the the OS memory space - it's just a more resource efficient way of doing things.

Not that I have to worry about resources in this case, but still, old habits. :)

Anyway, while I would _prefer_ to be able to use the built in port, with sio to save resources - there's other options. I can load the dos level version of X00 and depend on the more modern drivers getting COM1 into the VDM. I could also just abandon COM1 in favor of a pci mutliport card on a pcie bridge.

SIO v2 introduced it's pci support, so in theory I could get it to interact with the native com port on it's PCI home instead of at its dummy isa address, but i'd have to find it in the hardware tables and figure out how to teach sio where it's at.

I can make sio not attempt to service com1, and have validated that I can do hardware com1 with 6 vmodems via fossil - with all 7 acessable from the VDM. I do need to get com1 on fossil for doors and network packet handling though.

My rough plan is to use the built in port, along with 6 vmodems from sio, and a local only node to eat up my original 8 node WWIV 4.x license.

Doug Clark

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Re: Serial Port Shenanigans - ArcaOS 5.1.1 on a Lenovo M920t
« Reply #7 on: February 03, 2026, 06:14:57 pm »
Thanks for the FOSSIL overview.

I am a little confused by the vmodem vs physical modem stuff, but I have a very wild, shot in the dark, suggestion.  Try switching on CSM AND limiting your system to a single processor and see if SIO will run.  To limit to a single processor add /MAXCPU=1 to the ACPI.PSD line in CONFIG.SYS, e.g.

PSD = ACPI.PSD /MAXCPU=1

The reason I suggest this is the COM.SYS on my AOS 5.1 system is dated 8/3/2002 and SIO2K was released 6/6/2002, so they were both revised/released about the same time, suggesting that maybe the issue isn't in the COM stack/driver/interface but rather someplace else.

One processor should still be fast enough to handle multiple BBS "lines" - after all people were running multi-line BBS on machines before there were multi-core processor machines.

AmbulatoryCorpse

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Re: Serial Port Shenanigans - ArcaOS 5.1.1 on a Lenovo M920t
« Reply #8 on: February 04, 2026, 11:43:11 am »
Thanks for the FOSSIL overview.

I am a little confused by the vmodem vs physical modem stuff, but I have a very wild, shot in the dark, suggestion. 

The sio package includes a serial port emulator service (vmodem.sys) and a telnet server (vmodem.exe). Between them they can create around 250 virtual serial ports that interact with bbs software to handle guests from the internet parallel to actual physical phone lines. Default it provides 4, effectively emulating a 4 port multi serial card with modems.


Try switching on CSM AND limiting your system to a single processor and see if SIO will run.  To limit to a single processor add /MAXCPU=1 to the ACPI.PSD line in CONFIG.SYS, e.g.

PSD = ACPI.PSD /MAXCPU=1

The reason I suggest this is the COM.SYS on my AOS 5.1 system is dated 8/3/2002 and SIO2K was released 6/6/2002, so they were both revised/released about the same time, suggesting that maybe the issue isn't in the COM stack/driver/interface but rather someplace else.

One processor should still be fast enough to handle multiple BBS "lines" - after all people were running multi-line BBS on machines before there were multi-core processor machines.


At this point I'm pretty sure what I'm running into is sio trying to use things that aren't present in the modern LPC bus, but would be present in the ISA bus that the OS says it's talking to. I think proper fixes could be someone writing a replacement for (parts of) sio or someone writing an updated ISA driver that can recognize LPC emulating ISA then fix up other things. I'm trying to make sense of technical information beyond me, so yeah.

At any rate I will try apci and orther suggestions when I next have time.