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AuthorTopic: Headless Computing  (Read 1661 times)

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Offline trekiej

Headless Computing
« on: March 14, 2021, 03:52:42 AM »
Hello.
I was looking around the Internet and saw some computers that did not have a keyboard, mouse and monitor.
These are the minicomputer and mainframe types.

How can I find out more on how to connect to these machines?
Some of these had rs232 connections and needed, I believe, a VT100 terminal to communicate with them.

I did see some vt100 software on aminet and would like to try this with an Amiga and a PC or some other combination.
The other could be raspberry pi.
Is this any good for an Amiga 600?

I noticed that win98 has a telecom program. Is this usable?
Thanks.
Amiga 2000 Forever :)
Welcome to the Planar System.
 

Offline Pat the Cat

Re: Headless Computing
« Reply #1 on: March 14, 2021, 07:19:38 AM »
Good primer on hardware here;-

https://www.best-microcontroller-projects.com/how-rs232-works.html

Individual Amigas vary a bit in terms of maximum speed they can handle. 19200 is usually OK, some will go 38400 even with no fast RAM.

If the Amiga is running a lot of tasks, it might not be able to keep up.

The simplest connection is to swap pins 2 and 3 on the cable between machines, blob 4 and 5 pins on both machines (handshaking pins) and connect pin 7 between both machines (GND). That's on a 25 pin connector found on every Amiga.

The "HyperTerminal" program on Win98 can indeed be used, you have to select which COM port is in use on the PC side. The snag with the PC side is finding a machine which runs Win98 AND has a serial port. These can be 9 pin serial on PCs rather than 25 pin, but they are compatible in terms of voltage levels and timing (just use different pins).

This is for connecting very locally, ie in the same room. If you want to connect over the phone lines instead, to a remote computer, each machine needs to have a modem. And you don't swap the pins going to the modem, it handles the data swapping itself.

Typically a terminal emulator program on a computer (like NComm or Zterm on the Amiga) can also transfer files. The transmitting computer (the sourrce of the files) you point and click at a file using the menus, and the receiving end usually picks that up and starts receiving.

If you type on one keyboard, the text appears at the other end. To see what you have type, you usually have to select "local echo".
« Last Edit: March 14, 2021, 07:27:06 AM by Pat the Cat »
"To recurse is human. To iterate, divine."

A1200, Vanilla, Surf Squirrel, SD Card, KS 3.0/3.z, PCMCIA dev
A500, Vanilla, A570, Rev 5, KS 1.2/1.3 Testbench system
Rasp Pi, UAE4ARM, 3D laser scanner, experimental, hoping for AmigaOS4Arm, based on Watterott Fabscan Pi
 

Offline Pat the Cat

Re: Headless Computing
« Reply #2 on: March 14, 2021, 07:24:37 AM »
You can get a similar effect by using a 25 pin D connector on an Amiga serial port with pin pairs, 2 joined to 3, 4 joined to 5.

The Amiga thinks it's talking to something which is echoing back, when really it's talking to itself.

This is a cheaper way to test the serial port is working. An Amiga with a not working serial port doesn't report errors - it just doesn't WORK on serial.
"To recurse is human. To iterate, divine."

A1200, Vanilla, Surf Squirrel, SD Card, KS 3.0/3.z, PCMCIA dev
A500, Vanilla, A570, Rev 5, KS 1.2/1.3 Testbench system
Rasp Pi, UAE4ARM, 3D laser scanner, experimental, hoping for AmigaOS4Arm, based on Watterott Fabscan Pi
 

Offline trekiej

Re: Headless Computing
« Reply #3 on: March 14, 2021, 08:36:18 AM »
I guess the terminal is used to write code that is compiled by the server.
The output is the terminal, tape, disk, or printer.
Amiga 2000 Forever :)
Welcome to the Planar System.
 

Offline Pat the Cat

Re: Headless Computing
« Reply #4 on: March 14, 2021, 10:52:47 AM »
Not really. Most of the time when you connect to a remote computer, the first thing it asks for is a user name and password.

Back in the 50s-70s you'd type in your credentials, then send a load of punched cards or tape stream to a remote main frame for processing. It would be scheduled up as a batch job together with a load of other processor requests, and minutes, hours or even days later you'd get a response back. Typically a program would run in a fraction of a second (or more likely, be rejected because it contained typos).

Way before disks were invented. First there were punched cards, then paper tape, then magnetic tape.

Then micro chips became a big thing, so you could put the processor in the same unit as the keyboard and screen / printer (at first they didn't have CRT screen even). Hence the term "TeleTYpe" or TTY, Ever heard of PuTTY? Or ssh logging into a Pi?

Then wireless got invented so you didn't even need the cables anymore.
"To recurse is human. To iterate, divine."

A1200, Vanilla, Surf Squirrel, SD Card, KS 3.0/3.z, PCMCIA dev
A500, Vanilla, A570, Rev 5, KS 1.2/1.3 Testbench system
Rasp Pi, UAE4ARM, 3D laser scanner, experimental, hoping for AmigaOS4Arm, based on Watterott Fabscan Pi
 

Offline trekiej

Re: Headless Computing
« Reply #5 on: March 14, 2021, 05:00:46 PM »
I know Linux has a bunch of tty.
I do not have first hand experience with this, it sounds familiar.
Amiga 2000 Forever :)
Welcome to the Planar System.
 

Offline trekiej

Re: Headless Computing
« Reply #6 on: March 20, 2021, 04:55:57 AM »
I guess I could find a 68000 sbc and hook it up to a parallel port. This could be a co-processor of a sort.
Other computers definitely makes this obsolete. 
Amiga 2000 Forever :)
Welcome to the Planar System.
 

Offline Pat the Cat

Re: Headless Computing
« Reply #7 on: March 20, 2021, 02:04:43 PM »
I guess I could find a 68000 sbc and hook it up to a parallel port. This could be a co-processor of a sort.
Other computers definitely makes this obsolete.

... The parallel port is not a serial port. :o

You could in theory wire up a lot of "obsolete" tech to a serial port. Like, CNC gear for precision shaping metal. in theory you can talk to a 3d printer or similar Arduino powered hardware, the snag is that pretty much all of them are set to use higher serial speeds (115200 or higher) than the standard Amiga serial port can handle.
"To recurse is human. To iterate, divine."

A1200, Vanilla, Surf Squirrel, SD Card, KS 3.0/3.z, PCMCIA dev
A500, Vanilla, A570, Rev 5, KS 1.2/1.3 Testbench system
Rasp Pi, UAE4ARM, 3D laser scanner, experimental, hoping for AmigaOS4Arm, based on Watterott Fabscan Pi
 

Offline trekiej

Re: Headless Computing
« Reply #8 on: March 20, 2021, 11:08:31 PM »
Yes, I know that it is not. :)
edit:
I was throwing that one in as another way to communicate.
« Last Edit: March 20, 2021, 11:25:44 PM by trekiej »
Amiga 2000 Forever :)
Welcome to the Planar System.
 

Offline QuikSanz

Re: Headless Computing
« Reply #9 on: March 21, 2021, 02:59:46 AM »
 The IOBlix can handle 500Kb/sec on Zorro2. Should do some work, does on my printer.

Almost 500k on the serial too  ;)
« Last Edit: March 21, 2021, 03:55:52 AM by QuikSanz »
 

Offline trekiej

Re: Headless Computing
« Reply #10 on: March 21, 2021, 09:57:08 PM »
Thanks everyone, I will study this later.
It is just a hobby.
Amiga 2000 Forever :)
Welcome to the Planar System.