jakethompson1 wrote on 2022-06-24, 03:28:

You got me to dig out my serial/parallel cables and do a test. It's no comparison. If you can find a "bridge" machine with a rea […]
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Delphius wrote on 2022-06-24, 01:58:

I just tried a similar config with nocrtscts, and still no luck. My vb is running ubuntu 18.04 and my raspberry pi 3b+ is running the newest version of raspberry os. I have tried two different vintage machines, both of them being socket 7 so maybe related. One is an AN430TX chipset with 233mmx, and the other is my HP Omnibook 800CT. Both seem to do the same thing when using epppd. What is strange is I didn't seem to have any issues using the trumpet socket either. Maybe I will try disabling some cache or something to see if that helps. I also have a 486-75 dx laptop that I could try it on just to see if there is a hardware difference. I will also note that I have tested the serial ports between the an430tx and omnibook in dos via doom / duke3d so I know it works as well.

You got me to dig out my serial/parallel cables and do a test. It's no comparison. If you can find a "bridge" machine with a real parallel port as I have, I doubt you want to keep messing with serial...

I'm using a Panasonic Toughbook CF-51 on the Linux side and a Cyrix 486DX2/80 on the DOS side.

Parallel
Linux side:

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1modprobe -r lp
2modprobe plip
3ifconfig plip0 inet 172.16.0.1 pointopoint 172.16.0.2 netmask 255.255.255.0 up
4ifconfig plip0 arp

DOS side:

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1plip 0x60 7 0x378

FTP transfer with mTCP ftp client, speed: 2532352 bytes in 64.295 seconds (38.477 KBytes/sec)

Serial
Linux side: pppd /dev/ttyS0 172.16.0.1:172.16.0.2 crtscts noauth -detach debug
DOS side: epppd com2 115200 crtscts

FTP transfer with mTCP ftp client, speed: mTCP ftp client, 2532352 bytes in 253.715 seconds (9.765 KBytes/sec)

Parallel is even faster on my 386DX-40, probably fewer memory/cache wait states. And that machine has an 8250 serial and it was so frustratingly slow I gave up trying.

I would be very interested in trying this as an option. I have a few XP laptops around that might be good for that, but I might even have a mini pc with a parallel that could be used.

jakethompson1 wrote on 2022-06-24, 03:39:

Delphius wrote on 2022-06-24, 03:33:

Still going to test it some more, and make sure everything actually routes correctly. But everything seems to be happy now. I am wondering if there is a work around for this, as it would be nice not to have to keep the cache disabled.

No way, cache should have nothing to do with it. I'm guessing power cycling instead of hot-plugging the serial cable might make a difference though...

What kind of speed are you getting for something simple like ftp?

That's really what it is I have confirmed it. I have been trying to get that to work with the cache enabled for at least a couple of weeks. I have tried several different combinations of pppd settings and nothing has worked. With cache disabled, it connects immediately no issues every time. With cache back on, not a single connection. I will test this on the omnibook as well but I am pretty certain of the results. Pinging google is fine so far, I will let you know with FTP.

I have confirmed this is the same with the Omnibook 800CT which is running at 166mmx. With the external cache enabled epppd.exe will not initialize connection. With external cache disabled, it connects immediately with no issues.

This is good news in that the method still works and provides a way of getting TCP/IP connection via serial, but can also be limiting for connecting it to kali / dali for use in multiplayer IPX games like doom, duke3d, war2, etc. Ethernet is still an option for me, but I was hoping to find something that wasn't reliant on PCI hardware and working packet drivers. Maybe there is still a work around for this, or PLIP and parallel is the better way to go for that particular application.

You could also try SLIP instead of PPP.

I would have never disabled the cache, and thus have never figured this out. So clearly the timing loop in EPPPD is broken if it is speed dependent. But that doesn't make sense to me either, because any reasonably written serial code will ensure the UART buffer has space before trying to send another byte.

EPPPD has a debug version (EPPPDD - larger file size and an extra 'D'), and there are several versions of it floating around. You might want to try both of those options.

Delphius, What exactly made you decide to turn off the cache and try epppd again ?

I thought I saw another thread yesterday mentioning the cache disabling but I can't find it anymore.

Alternate toss all Nullmodem Cable Stuff and "Second Machine"

Buy ESP8266 Module, MAX2323 Module, Jumper wires
and connect both together
(VCC, GND, RX/TX "cross")

Flash Slipmodem Firmware.
Configure Access Point. (Telnet to ESP8266.. does not work with mbrutmans Telnet client)
Load 8250 Packet Driver (SLIP)
Go Online over ESP8266 (Acting as Slip Router) connected to Serialport of Retro PC.

For Example:
https://www.ebay.de/itm/255283221941
https://www.ebay.de/itm/284103777744
note 2 Diodes 1N4001 are needed to drop 5V to at least 3,6V.
5V -->|-->|-- 3,6V ESP/MAX232..
Or use Voltage Regulator, or find MAX2323 Module with 3,3V Output

Sigh ... Those devices *do* work with the mTCP Telnet. You have to set echoing and get the carriage return/line feed/new line character combination correct.

Rich at the TheOldNet provides the specific settings with his devices using the https://github.com/martin-ger/esp_slip_router firmware. He instructs you to use Alt-E and Alt-N first in the Telnet client to turn on local echoing and set the correct newline sequence.

jakethompson1 wrote on 2022-06-24, 16:25:

You could also try SLIP instead of PPP.

Interesting I will see what options are available for SLIP.

mbbrutman wrote on 2022-06-24, 16:33:

I would have never disabled the cache, and thus have never figured this out. So clearly the timing loop in EPPPD is broken if it is speed dependent. But that doesn't make sense to me either, because any reasonably written serial code will ensure the UART buffer has space before trying to send another byte.

EPPPD has a debug version (EPPPDD - larger file size and an extra 'D'), and there are several versions of it floating around. You might want to try both of those options.

Ok sounds good I will try and do some debugging and see if I can find out more information. I will also try version dosppp05 which is the only other version I have found so far. Maybe it is a bug in 06 or I might just get lucky with 05.

weedeewee wrote on 2022-06-24, 16:44:

Delphius, What exactly made you decide to turn off the cache and try epppd again ?

I thought I saw another thread yesterday mentioning the cache disabling but I can't find it anymore.

The main difference I was seeing between people who were reporting it working or not was generation / speed. I had literally tried everything else I could think of and was pretty much given up. It's funny because the thought of the cache was at the back of my mind for a while so it wasn't until I had no other options that I thought to check.

My AN430TX is from a Sony PCV-100 and the bios is pretty limited. But it gives me an option to Disable System Cache, and a Deturbo option right next to it. The deturbo description says that it slows down the CPU, but does not specify that it turns off CPU cache but I assume that's what it does. Either of those options alone will make it work, but both of them on together is a no go.

The Omnibook just has one option and its pretty much just called Disable System Cache. Both computers respond exactly the same.

matze79 wrote on 2022-06-24, 21:10:

Alternate toss all Nullmodem Cable Stuff and "Second Machine" […]
Show full quote

Alternate toss all Nullmodem Cable Stuff and "Second Machine"

Buy ESP8266 Module, MAX2323 Module, Jumper wires
and connect both together
(VCC, GND, RX/TX "cross")

Flash Slipmodem Firmware.
Configure Access Point. (Telnet to ESP8266.. does not work with mbrutmans Telnet client)
Load 8250 Packet Driver (SLIP)
Go Online over ESP8266 (Acting as Slip Router) connected to Serialport of Retro PC.

wifimodem1.jpg
wifimodem2.jpg

For Example:
https://www.ebay.de/itm/255283221941
https://www.ebay.de/itm/284103777744
note 2 Diodes 1N4001 are needed to drop 5V to at least 3,6V.
5V -->|-->|-- 3,6V ESP/MAX232..
Or use Voltage Regulator, or find MAX2323 Module with 3,3V Output

This is cool and I would definitely consider this as an option too.