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per
July 26th, 2008, 01:38 PM
Is it possible to just hook up any old computer (like the Altair 8800) to a modern computer through a RS-232 cable (and a terminal emulation program like 'hypertrm' or 'terminal'), or do you need some other stuff like a modem?

I don't plan to use this info (except for maybe transfering stuff to my Amiga500), and I'm just curious. :rolleyes: Anyway, if I ever get my hands on an Altair (most unlikely to happen), I might need this info.

tezza
July 26th, 2008, 03:06 PM
You shouldn't need a modem..at least not one which converts the signals to analogue.

You just need communications software and an RS-232 port on both machines and a cable compatible with the connectors.

However, the cable needs to be the right one. Not all RS232 cables will work just because they fit the plugs. Most vintage RS-232 cables were designed to run from a computer to a printer or modem. Ones that were designed for direct machine to machine connection had the transmit and received pins reversed.

Alternatively it was possible to use a printer/modem cable but you needed an adaptor called a null modem between the two machines which reversed the pins.

Tez

Dwight Elvey
July 26th, 2008, 08:24 PM
Hi
I recommend getting a RS-232 light box and learn how to use
it.
It will save you hours of frustration.
Dwight

modem7
July 27th, 2008, 01:04 AM
except for maybe transfering stuff to my Amiga500
For transferring files, the software running on each computer will need to support a common file transfer protocol.

For example, in the 80's, I had a CP/M computer that had 8" floppy drives and when I wanted to give a file to others who had a CP/M computer with 5.25" drives, the usual procedure was something like:

1. Use a suitable RS232 cable to interconnect the computers (varied according to the computer).
2. Set serial port on both computers to use same settings, eg. 1200/N/8/1
3. Computer A - run terminal software (eg. PTERM.COM).
4. Computer B - run terminal software (eg. TE.COM).
5. Type a few keys at each computer to verify that comms okay.
6. Computer A - do key sequence (or whatever) to send a file via the XMODEM protocol, then specify the file.
7. Computer B - do key sequence (or whatever) to receive a file via the XMODEM protocol.

modem7
July 30th, 2008, 01:52 AM
For transferring files, the software running on each computer will need to support a common file transfer protocol.
For the PC end, you could use the 1987 version of Procomm at http://members.dodo.com.au/~slappanel555/software.htm
It supports the following file transfer protocols: Xmodem, Kermit, Telink, Modem7, Ymodem, Ymodem Batch, ASCII
You would then need to find similar software for your old computer that supports one of those protocols.

Terry Yager
August 4th, 2008, 06:12 PM
For the PC end, you could use the 1987 version of Procomm at http://members.dodo.com.au/~slappanel555/software.htm
It supports the following file transfer protocols: Xmodem, Kermit, Telink, Modem7, Ymodem, Ymodem Batch, ASCII
You would then need to find similar software for your old computer that supports one of those protocols.

Not to sound fanatical on this religious issue, but my preference would be Telix (for DOS). YMODEM Batch is kewl, but Telix supports ZMODEM, which allows for picking up lost downloads right from where they were dropped. I'm pretty sure it'll run on any hardware that Procomm will.

For the Amiga, Kermit is probably the weapon of choice if you can't find ZMODEM, while a CP/M box like the Altair will want MODEM7 or Kermit

--T

modem7
August 6th, 2008, 04:04 AM
Not to sound fanatical on this religious issue, but my preference would be Telix (for DOS).
To please the religious folk, I've added Telix (for DOS) to the site.
In addition to Telix version 3.12, I've included version 1.00 because I found that 1.00 has two protocols that were later dropped (Jmodem and Lynx).
http://members.dodo.com.au/~slappanel555/software.htm

mistamidget
August 18th, 2008, 04:39 AM
A way to implement a file transfer process is to convert your files to .hex format and then just type them to the console while capturing the text (hyperterminal standard function)
this will transfer any filetype both ways cpm -> pc and pc -> cpm (you use pip from con: and then ^z to get stuff back from the pc.