Re: stirring the pot of frustration. the final Xmodem solution.

[Richard Deane]

HI John, please can you give a few details, like the sw config on pi, and the wiring link to your cp/m system.

I used a Pi previously to capture serial printout from CP/M and bridge over the network to a printer network port, worked ok but lacked useful printer emulations.

I now have a dedicated pi running retro-printer ( £50 sw, which has retro printer emulations and a copy protection dongle). That works great.

Richard

On Wed, 30 Jul 2025 at 19:13, John Galt <furba...@gmail.com> wrote:

starting back years ago now i wrote about my frustrating experience with the crop of WIFI modems that have been around for vintage machines.

The big issue i had with them was they were either in TELNET mode or not.

Telnet mode created a block with file transfers where uploads would work but a download would result in communication errors that always terminated the download.

because of various ways around this issue i kind of didn't care and moved on.

Recently i got back around to working on different networking protocols using the altair.

That lead me to wanting to access E-mails using the altair as a terminal with IMP 2.45.

i had still been using the usual array of wifi modems which all stink.

they lock up and flip out with escape codes. most BBS still around use escape codes for the text effects on terminals.

long story short i just got fed up with the constant lock ups with the wifi modem and decided to just directly connect my raspberry pi to the altair duino serial port. 

i would use the pi as the gateway and that would be the end.

little did i know how much of a bottleneck these wifi modems were connecting at 9600 without the wifi modem suddenly everything became the speed of light at real 9600. 

i had been using these wifi modems on other vintage machines with equal annoyance.

using the pi

now i have access to websites, email, image display and Xmodem transfers however i like with out any issues.
and i can connect to all these same Telnet BBS just like with the wifi modem and experience them without issues.

wish i had just done all this years ago but i just thought wifi modems were cute and a nice way to have a modem like the old days.

the pi is the way.

the issue was always these wifi modems and nothing else.

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[John Galt]

I don't know what a sw config means.

If we are talking printers, i have a few different setups for the altair-duino.

I have a serial to parallel converter from B&B that is about 40 years old that uses the 9pin serial on the original altair-pro kit.

The 320 is a parallel printer and i never installed the serial card in it. this also requires a null modem converter.

I have a 192 which has a serial card and in that case it is a direct connection with a 9 to 25 pin serial cable without a null modem converter.

I have an IBM 192 which is parallel and uses a similar setup to the 320.

On the PI itself i have a GPIO to 9 pin serial converter that runs through a serial switch since i have multiple devices sharing a single serial port.

I never heard of Retro-printer before so i looked it up. 

it is not something i need as i use real hardware for output.

The picture of the raspberry pi on top of the 320 printer in my situation had nothing to do with the printer it was just laying on top of the printer when i took the photo due to the cables and power supply needing support for the 9pin serial adapter.

my situation in the original post was discovering the short comings of all retro wifi modems blocking file transfers and throttling baud rates with constant lockup and crashes of the wifi firmware on these types of modems.

the raspberry pi now acts as my wifi modem giving me direct internet access, Mp/m , Cp/net, and a host of other tools to make vintage computer use a pleasure.

I never tried or needed to print to a network printer from the altair.

on the PI GPIO to serial wiring I'm using 3.3v, Ground, TX and RX for the serial converter.

you could also use terminal software to capture printer output. putty or teraterm and a serial to usb or micro usb to usb could be used.

just connect your terminal software as usual with a log file and any serial traffic on the port will be captured by the terminal software and can be output later.

you can also use PIP to send files to the printer and format it using [T] to convert tabs [L],[U] to convert all lower or all uppercase. [N] will add sequential line numbers to each line of output allowing for some python or perl scripts to search information faster.

[Richard Deane]

Sorry, I was too abbreviated. Which software are you using for your use case in the rpi, and how is it configured?

I use mincom on my rpi as terminal to access CP/M systems over direct serial and found that the xmodem UI of minicom has a bug , a mismatch between actual folders and files, and a wrong one would often get selected so actual had completely different name to the one visually selected.

I am always on the lookout for a good serial terminal on linux which handles xmodem file transfer.

Secure CRT is good but too expensive when 30-day eval expires.

cheers

Richard

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[John Galt]

===

Sorry, I was too abbreviated. Which software are you using for your use case in the rpi, and how is it configured?

===

I like Twister O/S its setup with serial login along with Xwindows Gui and telnet, ssh, ftp, i also have various ports to allow MP/M access if i run the Z80 pack.

i have accounts setup for different machines with diffferent shell settings. the Altair uses a Color Xterm configuration as i use the FABGL Ansi Terminal which provides graphics and VT100 capabilities.

from the serial connection i have access to anything i wish.

connection is done from the Altair using IMP, i find it better then using Kermit. Kermit Server is problematic.

For file transfers i have Xmodem, Ymodem and Zmodem installed on the Pi as well. i can do batch transfers if i wish but it is better to use ARC(compression) put everything i want into a single archive then send i over using SX(send xmodem)

configure wise it is just an open system and i can access ports or usually just use the command line and i have all my applications ready to go for each user.

very easy to send files back and forth at proper 9600Baud.

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===

I use mincom on my rpi as terminal to access CP/M systems over direct serial and found that the xmodem UI of minicom has a bug , a mismatch between actual folders and files, and a wrong one would often get selected so actual had completely different name to the one visually selected.

===

I used minicom as well. Its basically a ascii Gui script sitting on top of SX,SY,SZ,RX,RY,RZ utilities, it is buggy and isn't great looking. so i have configured a inhouse BBS where i can manage the files cleaner and have descriptions.

I can pull files back and forth that way or i have a in house FTP as well.  

i made a lot of my own scripts in perl and python to move things around. i have MUTT setup so i can send Gmail from the command line as well works great with the altair and imp.

i also use my Github to move things around. i'm in the process of creating a html portal to my github to make it easy for Elinks and Lynx to access my files from vintage machines.

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===

I am always on the lookout for a good serial terminal on linux which handles xmodem file transfer.

Secure CRT is good but too expensive when 30-day eval expires.

===

everything basically comes back to SX,RX,SY,RY,RZ,SZ for X,Y,Z modem transfers and then various applications sit on top of them.

the issue is trying to manage the files in directories and then trying to archive them in such a way where you can put some blurb about what a file is.

internally a inhouse BBS works great or a inhouse HTML server which i also have.

i have a local HTML in house and since i have no issues with ELinks as a primary browser for text terminals i can use that to manage files as well creating scripts to dynamically change HTML pages.

or just do it by hand if needed.

i have not had the need for high level of protection for xmodem transfers other then putting encryption or password protection when creating an archive that will go out via xmodem.

you get into different ssh with more protections.

[Richard Deane]

Thank you, very useful background

RIchard

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[John Galt]

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