a question on the old days of comms

Beano · 16-10-2013 11:39AM #1

I was having a nostalgic conversation earlier about the good ol' days of 56K modems and the joys thereof. I had a look at the wikipedia article on them and something is confusing me. In the section on speed it says :

In 8-N-1 connections (1 start bit, 8 data bits, No parity bit, 1 stop bit), which were typical before LAPM became widespread, the actual throughput is a maximum of 5.6 kilobits per second, since ten bits are transmitted for every 8-bit byte

56K modems ran at 56kilobits a second nominal speed. that is 7 kilobytes a second. take off the start and stop bits that leaves 5.6 kilobytes a second actual throughput. where is the article getting 5.6 kilobits a second from?

niallb · 16-10-2013 01:10PM

It's a mistake. 56k modems would transfer close to 5 kilobytes per second.

56k modems varied wildly though, and depending on your ISP, you might as well have had a 33k one, because that was as fast as the shared standards would go.
Generally a good link would give you transfers of about 3.5kb per second.
If you did your homework and bought a modem that supported the same standards as your ISP's on the other end you might stretch it a bit.

Beano · 16-10-2013 01:19PM

thanks for confirming that i havent gone totally senile. I would edit the article and correct the mistake but i'm sure some cretin would come along 5 minutes later and revert the change. Now excuse me while i go and tell some kids to get off my lawn.

rozeboosje · 16-10-2013 01:21PM

ZOMG how did people ever get pr0n in them days?

Alun · 16-10-2013 01:23PM

56k modem? Luxury!! ... my first foray into the online world (Bix (Byte Information eXchange) and CompuServe) was done using a 300bps acoustic coupler

http://en.wikipedia.org/wiki/Acoustic_coupler

Beano · 16-10-2013 01:36PM

you must be even older than me. I think i remember using an acoustic coupler to connect to a bulletin board but i dont think it was as slow as 300 baud.

Alun · 16-10-2013 01:42PM

Yes, I'm pretty ancient

Acoustic modems were only 150 or 300bps IIRC. After that it was good old Hayes or Hayes compatible modems from 1200bps upwards.

rozeboosje · 16-10-2013 02:02PM

BUT YOU COULD ALMOST TRIGGER WWIII WITH THOSE I KNOW IT'S TRUE I SAW IT IN A MOVIE ONCE O_o

Beano · 16-10-2013 02:06PM

that wasnt a movie it was a documentary.

FSL · 16-10-2013 02:49PM

The first data transmission I used involved an audio coupler and the data was transferred from a reel of magnetic tape on one end to another on the other. The state of the art mainframe, an IBM 360/50, had 512k bytes of memory. The data transmission was a completely separate unit.

niallb · 17-10-2013 08:28AM

Anyone else remember building a light sensor and taping it to the television during a BBC show to download software encoded into light pulses...

MrTime · 04-11-2013 10:27PM

niallb wrote: »

Anyone else remember building a light sensor and taping it to the television during a BBC show to download software encoded into light pulses...

Think it was Tomorrows world on BBC
a BASIC program
recorded to audio cassette

probably for BBC micro ; or maybe even Sinclair ZX80

niallb · 05-11-2013 03:57PM

MrTime wrote: »

Think it was Tomorrows world on BBC
a BASIC program
recorded to audio cassette

probably for BBC micro ; or maybe even Sinclair ZX80

Close - ZX-81!

a question on the old days of comms

Comments