Jump to content
IGNORED

Simple (single) RS-232 interface ?


Level42
 Share

Recommended Posts

BITD there were loads of centronics/parallel/printer interfaces for the A8 as alternative to the 850......but were there any RS-232 alternatives ?

 

With a single RS-232 port ?

 

I think it would be a breeze to build one, as the very first SIO2PC I built into my 130XE in the late 90's was simply a "piggy back" solderered MAX232 chip on the SIO port, just because it needed the +5 and 0V levels from the SIO port converted to standard RS-232.

 

But was there anything "production" like...maybe something compatible with the 850 software wise ?

 

I'd like to hook up a RS-232 printing device to the A8....a simple schematic would be fine too....but there needs to be some simple software support from BASIC....

Edited by Level42
  • Like 1
Link to comment
Share on other sites

BITD there were loads of centronics/parallel/printer interfaces for the A8 as alternative to the 850......but were there any RS-232 alternatives ?

 

With a single RS-232 port ?

 

I think it would be a breeze to build one, as the very first SIO2PC I built into my 130XE in the late 90's was simply a "piggy back" solderered MAX232 chip on the SIO port, just because it needed the +5 and 0V levels from the SIO port converted to standard RS-232.

 

But was there anything "production" like...maybe something compatible with the 850 software wise ?

 

I'd like to hook up a RS-232 printing device to the A8....a simple schematic would be fine too....but there needs to be some simple software support from BASIC....

 

You could reverse-engineer something like the ICD P:R: Connection or an 850 easily enough; the driver files for both devices are readily available online, and I imagine any other similar devices' drivers are out there too. Shouldn't be all that hard to hack something together if you're motivated.

Link to comment
Share on other sites

I remember a device called the R-Verter. SIO cable on one end and db25 male standard serial port on the other for plugging into the modem. I think it was based on the MAX232.

Description with picture here: https://www.atarimagazines.com/compute/issue51/237_2_NEWS_PRODUCTS_RS-232_Modem_Adapter_For_Atari.php

 

Edit: Here's another device discussed last year in a different thread: http://atariage.com/forums/topic/266047-digital-devices-u-call-universal-modem-interface/?p=3771380

Edited by RodLightning
Link to comment
Share on other sites

How to make your own R:Verter interface:
https://www.atarimax.com/freenet/freenet_material/5.8-BitComputersSupportArea/7.TechnicalResourceCenter/showarticle.php?71

I have not made one myself, nor ever used one, as I only ever had 850, P:R: Connection, then an MIO.

I am curious however, if an R:Verter device could do 19,200 (or higher) reliably, as the limitation of the 850/PRC was purely the sampling rate of the RIOTs. This one appears to use just a MAX232 IC level converter (as OP suggested) and some other very simple components. Hence the requirement to load the driver from disk.

Edit: My question is answered right in the linked article haha.

I am not sure if all handlers support 19200 baud, but I have
used my interface connected via a null modem cable to an IBM to
transfer files at 19200 baud and have had no problems. I tried
38400 baud (by patching the handler) and too many errors were
generated.

and:

Note: CTS is not supported so you cannot use RTS/CTS handshaking.
Only XON/XOFF could be used.
Edited by Nezgar
  • Like 1
Link to comment
Share on other sites

So we've seen many people make very simple no-solder serial SIO2PC connections, between Atari SIO and a PC Serial connection. (at least at standard lower speeds) If this 'generally works', and the main function of the MAX232 in the R:Verter-type device is to just up the 5V to 10V, maybe this would 'mostly' work with just simple direct wiring?

 

Unless there's some other logic like signal inversions going on in this interface i'm overlooking.

Edited by Nezgar
  • Like 1
Link to comment
Share on other sites

BITD there were loads of centronics/parallel/printer interfaces for the A8 as alternative to the 850......but were there any RS-232 alternatives ?

 

With a single RS-232 port ?

 

I think it would be a breeze to build one, as the very first SIO2PC I built into my 130XE in the late 90's was simply a "piggy back" solderered MAX232 chip on the SIO port, just because it needed the +5 and 0V levels from the SIO port converted to standard RS-232.

 

But was there anything "production" like...maybe something compatible with the 850 software wise ?

 

I'd like to hook up a RS-232 printing device to the A8....a simple schematic would be fine too....but there needs to be some simple software support from BASIC....

I believe the serial SIO2PC was an adaptation of the R-Verter interface, adding the COMMAND signal connection to one of the RS232 handshake lines.

 

Commercially the R-Verter was used as an external device by Supra for Atari 8-bit compatibility, I have one I got with a Supra 2400 modem in the late 80's, and also internally by Atari in the SX212.

 

A disadvantage of the R-Verter interface is that there is no handshaking available to implement hardware flow control.

 

The CSS Black Box is the only device I know of which came with RS232 hardware flow control, but there is a replacement serial port driver for the MIO which adds this feature.

  • Like 2
Link to comment
Share on other sites

there was a couple pictures and schematics of r verters that had control lines, you would think knowing what we know now a full speed buffered flow controlled rverter could be done...

Why couldn't we use a joystick port for the extra control lines? There are already 2 interrupt generating inputs on SIO, and the joystick port has 4 bi-directional lines plus 1 input to GTIA.

  • Like 1
Link to comment
Share on other sites

Another thought... you would think it would it be possible, with the right hardware and handler, for a fully buffered non concurrent mode handler. The handler would issue a regular stream of pull/push type SIO frames. Hardware flow control would be handled by the hardware device. DTR would be relayed via a some SIO status code, and CTS would be handled by the hardware device, depending on how fast the Atari is requesting received data frames.

 

Using non-concurrent frames may allow reliable speeds above 19,200bps like disk access IO, and could be multiplexed with simultaneous communication with other SIO devices.

Link to comment
Share on other sites

I did a lot of joystick to ST or IBM transfers back in the day. The original MPP RS232 driver will do 300 BAUD and I think Bob Puff wrote a handler that will do 1200 BAUD. If it can be a one way handler i.e. doesn't need to accept data from printer, 19,200 BAUD is easily reached. It won't be as popular as a hardware chip like a parallel buss 6551 but should work. Just requires a diode or two and resistor to keep data input to 5V levels.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
 Share

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...