How fast a modem can an Atari run?

[ACML]

I want to say I'm 99.99% sure I ran a 1200 baud Hayes back in the day, but will it run a 2400, 4800 or 9600 baud modem? I think the SIO is limited to 9600 baud. Anyone every run one at 9600 baud?

 

[Justin Payne]

You see this?

 

http://atariage.com/forums/topic/188966-can-the-lowely-8bit-atari-use-9600-or-greater-baud-rates-via-land-lines/

[BillC]

I want to say I'm 99.99% sure I ran a 1200 baud Hayes back in the day, but will it run a 2400, 4800 or 9600 baud modem? I think the SIO is limited to 9600 baud. Anyone every run one at 9600 baud?

 

An 850 modem port has a a maximum speed of 9600 baud, this would only support a 4800 baud modem connection if hardware compression is enabled.

 

In the early 90's I connected to CompuServe via an MIO modem port(which is capable of 19200 baud), I had a 14400 baud modem which I restricted to 9600 baud with hardware compression enabled, which is effectively 19200 baud with hardware compression disabled.

 

The Blackbox and I believe the P:R: Connection modem port also support 19200 baud. It may be possible for an R-Verter interface to support even higher connection speeds as well(I believe the RS232 version of the SIO2PC does and it has similar hardware design) but this would require a driver that supported the higher speeds.

[Marius]

On Mathy's blackbox page http://www.mathyvannisselroy.nl/blackbox.htmI read about something about ideas for a higher speed than 19200 baud for the blackbox R: port. It is interesting to read.

 

BlackBox has an excellent R: port, which is hardware flow controlled. It's awesome. I did run my BBS using a blackbox back in 1995-2000.

[Bryan]

Well, people have done SIO at very high speeds that could support a 57.6Kbps modem, but it would consume most of the CPU. The PBI would be better for fast communications.

[Stormtrooper of Death]

I had a P:R connection and i used an external modem of 14400 or 19200 baud.

[ricortes]

I think all modern modems autobaud on both ends. That is, connect to a 56k modem with your Atari set at 19.2k and the connection between the two will be fixed at 19.2k for the session. Now when you dial out, the modem will connect to the host at anywhere from 300 BAUD to 56k depending on what the host offers and the quality of the phone line. Actually 56k is a misnomer but that is another kettle of fish. After the connections are made, it is "Hurry up and wait", by that I mean if you dial a host that is at 2400 BAUD, the 19k connection between computer and modem is able to keep up easily but you will never get 19k through put because the host/modem are only at 2400 BAUD. Reverse hurry up and wait if your modem connects at 56k and your terminal sets the R: line to 2400 BAUD.

 

To answer your question specifically, fastest POKEY can go is system clock/16 or 1789500/16 or 112k BAUD. This is close enough to the standard 115k BAUD that it works.

 

Then there is the practical that you seem to be hinting at. I can only read with comprehension ~2400 BAUD. Doesn't matter if it is a 40 column screen or a 132 column screen. When transferring files it would becomes another hurry up and wait situation. Stock Atari drives only do 19k, so if you plan on doing anything practical with the data like reading it or saving it, you reach a point of diminishing returns. A 36k BAUD connection to host won't be close to twice as fast as a 19k BAUD connection because you are still spending a huge slice of time doing disk I/O at 19k.

[Stormtrooper of Death]

In my old BBS times, i used the 130XE ramdisk for fast file storage when downloading files..... then when file was in ramdisk, i copied it to the 1050 diskdrive.

[fujidude]

An 850 modem port has a a maximum speed of 9600 baud, this would only support a 4800 baud modem connection if hardware compression is enabled.

 

In the early 90's I connected to CompuServe via an MIO modem port(which is capable of 19200 baud), I had a 14400 baud modem which I restricted to 9600 baud with hardware compression enabled, which is effectively 19200 baud with hardware compression disabled.

 

The Blackbox and I believe the P:R: Connection modem port also support 19200 baud. It may be possible for an R-Verter interface to support even higher connection speeds as well(I believe the RS232 version of the SIO2PC does and it has similar hardware design) but this would require a driver that supported the higher speeds.

 

The BlackBox supported 192000, and also supported hardware flow control (CTS/RTS). If the MIO supports HW flow control, it would have been best set the modem for 144000 with compression. That way you get the maximum speed possible (up to 192000), and the flow control keeps any overflow from happening.

Edited November 26, 2016 by fujidude

[Alfred]

Using the Black Box and assembly language, I was able to run zmodem transfers at 19.2 between my XL and a pc over a null modem cable. The screen had to be off and while the overall throughput was nothing like 19.2 due to disk transfers, it was just barely able to drive the port at that speed.

[BillC]

 

The BlackBox supported 192000, and also supported hardware flow control (CTS/RTS). If the MIO supports HW flow control, it would have been best set the modem for 144000 with compression. That way you get the maximum speed possible (up to 192000), and the flow control keeps any overflow from happening.

The stock MIO serial port driver doesn't support HW flow control, however Len Spencer created an updated driver which does.

http://www.lenardspencer.com/Lenspencer/hyperspd.html

[fujidude]

The stock MIO serial port driver doesn't support HW flow control, however Len Spencer created an updated driver which does.

http://www.lenardspencer.com/Lenspencer/hyperspd.html

 

So the MIO hardware supports it, but the OEM driver didn't. Nice that Len came up with a solution for MIO users.

[_The Doctor__]

Yes and I wish someone would frankenstein the flow control into the mio rom so the driver would be standard

[Kyle22]

I have been thinking for literally years about building an R:Verter type device that also uses a joystick port for flow control signals. The RS232 level converters are dirt cheap these days.

 

With a proper driver, I would expect it to do 57.6 or so.

 

(Yes, I have done 57.6 with the Atari and a TeleVideo CP/M machine using an R:Verter type cable).

[Xebec]

So to follow up -- Is there no way to make the 850 Interface reliable at 19200 bps? It looks like it kinda works, but kinda doesn't.. Is there any combo of software and flow control that works at 19200?

 

Are the only 3 choices for connecting to RS232 the 850, the ICD MIO, and CSS Blackbox? Are any of the 'better than 850' options available for purchase today?

[+DrVenkman]

Are the only 3 choices for connecting to RS232 the 850, the ICD MIO, and CSS Blackbox? Are any of the 'better than 850' options available for purchase today?

 

The ICD P:R:Connection has two RS232 ports and a Centronics parallel port, but it's limited to 9600 baud (but up to that speed it works great )

[+David_P]

So to follow up -- Is there no way to make the 850 Interface reliable at 19200 bps? It looks like it kinda works, but kinda doesn't.. Is there any combo of software and flow control that works at 19200?

 

Are the only 3 choices for connecting to RS232 the 850, the ICD MIO, and CSS Blackbox? Are any of the 'better than 850' options available for purchase today?

 

MetalGuy may still have new build MIOs for sale.

[+kheller2]

Build an RVerter. 19K works.

[gozar]

Build an RVerter. 19K works.

 

Directions?

[+kheller2]

Here is one: http://www.realdos.net/RVerter.html

[fujidude]

As my Atari didn't have legs, it couldn't even walk much less run.

 

But seriously, I only had an opportunity to run a 1200bps modem on my Atari using a Black Box. It was an Atari SX212(?) which had both a standard RS232 serial interface as well as an Atari SIO one. I used the RS232 via a Black Box. It was cool because when I bought a 80486 based PC (in the 1st half of 1993), I actually used the SX212 on it for a bit. Later that year, I bought an internal Zoom 14.4 for my 80486 based box. After that, I didn't really use the Atari modem any more.