Making an SIO2PC cable

[Tezz]

Hi all, I'm finally moving house and can get my set-up back up and running soon. I want to immediately put together an SIO2PC cable which is way overdue. I have several spare Atari SIO cables. There's a lot of info on the web with the schematics etc although, I have one question regarding the MAX-232. Here in the UK the obvious electronic supplier is Maplin (although overpriced) they have various 232 tranmitters and receivers here:

 

http://www.maplin.co.uk/search.aspx?MenuNo...=y&doy=15m2

 

Which is the correct one to use for the SIO2PC?

 

Thanks,

Tezz

[Rybags]

The second one looks closest.

The one I used (as per most project specs) is the 1489 series IC, which if I remember correctly has 14 pins.

The Atari provides +5 Volts, and the only external components were the resistor, diode and capacitor.

They don't seem to mention transfer rates on this one (unlike some of the others on the page). Default bit rate is only 19,200 but warp speed should be 57,600.

They have little JPG schematics on the page but they're next to useless.

 

Ed: transfer rate support would just mean that the IC can switch RS-232 0/1 voltage states quickly enough to be able to provide smooth data transmission.

 

MAX232CPE RS-232 Transmitter/Receiver

 

A dual RS-232 receiver/transmitter that meets all the EIA RS-232C specifications while requiring only a single +5V supply. This significantly simplifies system design by removing the need to provide power supply voltages other than +5V. The IC has two on-board charge pump voltage convertors which generate +10V and -10V power supplies from the single +5V supply.

The IC contains four level translators, two of which convert TTL/CMOS input levels into ±9V RS-232 outputs ready for transmission, and two of which convert RS-232 inputs to 5V TTL/CMOS levels. The receivers have a nominal threshold of 13V, a typical hysteresis of 05V, and can operate with up to ±30V inputs.

Edited February 15, 2007 by Rybags

[Tezz]

The second one looks closest.

The one I used (as per most project specs) is the 1489 series IC, which if I remember correctly has 14 pins.

The Atari provides +5 Volts, and the only external components were the resistor, diode and capacitor.

They don't seem to mention transfer rates on this one (unlike some of the others on the page). Default bit rate is only 19,200 but warp speed should be 57,600.

They have little JPG schematics on the page but they're next to useless.

 

Ed: transfer rate support would just mean that the IC can switch RS-232 0/1 voltage states quickly enough to be able to provide smooth data transmission.

 

MAX232CPE RS-232 Transmitter/Receiver

 

A dual RS-232 receiver/transmitter that meets all the EIA RS-232C specifications while requiring only a single +5V supply. This significantly simplifies system design by removing the need to provide power supply voltages other than +5V. The IC has two on-board charge pump voltage convertors which generate +10V and -10V power supplies from the single +5V supply.

The IC contains four level translators, two of which convert TTL/CMOS input levels into ±9V RS-232 outputs ready for transmission, and two of which convert RS-232 inputs to 5V TTL/CMOS levels. The receivers have a nominal threshold of 13V, a typical hysteresis of 05V, and can operate with up to ±30V inputs.

 

That's great, thanks for the info. I would imagine that they will be able to clarify the rate for that one when I ask in the store. I'll bring those details that you've listed. (LOL, yea the JPG schematics on the site are as good as useless )

 

Regards,

Tezz

[a8isa1]

Hi all, I'm finally moving house and can get my set-up back up and running soon. I want to immediately put together an SIO2PC cable which is way overdue. I have several spare Atari SIO cables. There's a lot of info on the web with the schematics etc although, I have one question regarding the MAX-232. Here in the UK the obvious electronic supplier is Maplin (although overpriced) they have various 232 tranmitters and receivers here:

 

http://www.maplin.co.uk/search.aspx?MenuNo...=y&doy=15m2

 

Which is the correct one to use for the SIO2PC?

 

Thanks,

Tezz

 

Sidenote:

 

I purchased a 1489 two-chip SIO2PC and built a single chip 14C89 interface. Neither of these are compatible with my SWP ATR8000 (interface box with serial port, parallel port, floppy controller, and can run CP/M).

 

I wanted to build the MAX232 based SIO2PC but came across and article or two (not SIO2PC articles) which used the MAX233 chip for communications. I would have used the MAX232CPE, BTW. However, being mostly inept with the soldering iron I wanted to build the simplest circuit possible. The MAX233 (DIP-20) is functionally equivalent to the MAX232 but has the capacitors built-in. I thought I would be eliminating 16 solder joints so that's what I chose to build. The chip I did use is the MAX233CPP. It's relatively expensive but I got a couple free samples.

 

As it turned out I only eliminated 8-10 solder joints (can't remember) because some interconnections are still required. My build is ugly but in the end it all worked and the interface is fully compatible with my ATR8000.

 

Incidentally, I was told in Europe you have equivalent parts for the MAX232. I think ICL232 was the one mentioned to me but a search shows HIN232 and ST232 as well. I don't see any equivalents for the MAX233.

 

I have an impromptu schematic (EDIT: for the MAX233 circuit). PM me if you'd like to have it.

 

- Steve Sheppard

Edited February 15, 2007 by a8isa1

[Tezz]

Hey all, I got my parts from Maplin today. the MAX232 chip, the DB9 connector and hood and I have my spare SIO cable ready. I have a couple of pretty simple questions as I'm not totally up on schematics or exactly which way to put the cable together. Can I just simply use the SIO cable cut off one end and solder the correct leads listed to the db9 connector? or do I need to strip the SIO connector off and use a different cable all together?

 

I'm not totally clear on the schematics, my original Atari's SIO cable has these colours:

 

2 4 6 8 10 12

Yellow Green Red Unshielded Orange Black

 

1 3 5 7 9 11 13

Blue Pink White Grey Brown Light green Cyan

 

According to the documentation, on the db9 connector pins 2,3,9,7,5 are used so, does that simply mean that I can solder the wires according to colour? I mean on the schematic it says on the Atari side pins 5,3,7,6,10 match up with 2,3,7,9,5 on the pc (db9) side although the colours mentioned are different to my cable I should just be able to connect the correct pins up right?

 

On the Max chip I assume that i solder the ic pins 5 and 15 onto the atari pin 6/pc pin 5 and the ic pins 16 and 2 go to pin 10 of the atari side only. on the schematic it looks like the ic pins 1&3 are joined and also 4&5 are joined together? is that right?

 

Sorry if that sounds a bid dumb, I've done a lot of modding in the past but i'm new to a lot of the basics still.

Here's some photos attached

 

Thanks once again

Tezz

[Beetle]

Perhaps this schematic by MacFalkner (A.Bertram) is a bit more selfexplaining. I took it from his german

webpage rather to deeplinking it. SIO2PC german page

Besides the LEDs its the same interface.

 

 

Happy modding,

Beetle

Edited February 17, 2007 by Beetle

[Tezz]

Thanks Beetle, that schematic is a lot clearer. My max232 chip is the CPE. I'm not sure about the capacitors yet? I want to make sure I solder the correct connections to the correct points firstly

Edited February 24, 2007 by Tezz

[Beetle]

I edited the part regarding the capacitors. There are versions that could actually work with smaller capacitors. Just take care your capacitors (labelled C1 to C4) are big enough. The schematic you refered to uses 22µF, the one i linked uses 2,2µF i have an Interface that uses very tiny 0.1µF caps.

 

Of course you may built it without the LEDs, just leave them and their serial resistors out, they are for cosmetic only... may come in handy when you have problems.

Edited February 17, 2007 by Beetle

[Beetle]

Does anyone know where the Page with the url http://sog.com/atarimods/sio2pc1.html has gone?

It had the best, simplest schematic, imho.

[DamageX]

Mine has a 1489 and one diode...

[Rybags]

Since you're going to all the trouble, why not just build the APE interface inside your machine? I just did that and soldered the relevant wires directly to the motherboard SIO header.

 

I did that, and just cut a hole for the DB9 female plug.

 

Then it's just a case of using a PC serial cable.

 

Standard SIO devices can happily co-exist as well.

 

Here is an archive of the webpage "Have you modified your Atari Today?" - just unzip it, allowing it to create the full paths:

 

Atarimods.zip

 

I based my inbuilt interface on the one on this page. It has a little header on the board so that I can pull the machine apart but leave the PC serial plug in place.

[+Larry]

If you would choose to use the easier-to-build 1489 series, try hard to find a 14C89 (no substitutes). Some substitutes will work reliably, and some "not quite." For me, a MAX232 *always works* when it is properly assembled. I have no reason to doubt that the MAX233 would work as well, but I actually haven't built one. The one downside I have seen in personal experience is that the MAX's are susceptible to power surges, even when the equipment is protected by good surge protection. In actual Atari use, I can see no difference between a good 14C89 and a MAX232 interface.

-Larry

[Tezz]

Thanks for all the info everyone, I've got a much clearer picture about it now Now I know there's a number of solutions for an SIO2PC, that's partly where the confusion was browsing around various sites

 

Tezz

[ataridano]

I'd suggest the Max232 route, that chip generates the correct RS-232 voltages internally, the 1488 and 1489 chips do not, and the schematic show using a 1489 may or may not work because the voltages going to the PC are out of spec. I think Atarimax sells SIO2PC or APE adaptors, with their own little board. Not to take away from building one yourself, but I personally would rather not cut an SIO cable if I didn't absolutly have to!

[Tezz]

I'd suggest the Max232 route, that chip generates the correct RS-232 voltages internally, the 1488 and 1489 chips do not, and the schematic show using a 1489 may or may not work because the voltages going to the PC are out of spec. I think Atarimax sells SIO2PC or APE adaptors, with their own little board. Not to take away from building one yourself, but I personally would rather not cut an SIO cable if I didn't absolutly have to!

Thanks, Yea I decided to do just that, partly because I don't have enough spare time to look into building it correctly and also because I don't wanna get voltages or other stuff wrong. Like you say, I don't have to mess up an SIO cable either. For the sake of a small amount of money to get a manufactured one it's the best option in the end.

Tezz

[mimo]

I'd suggest the Max232 route, that chip generates the correct RS-232 voltages internally, the 1488 and 1489 chips do not, and the schematic show using a 1489 may or may not work because the voltages going to the PC are out of spec. I think Atarimax sells SIO2PC or APE adaptors, with their own little board. Not to take away from building one yourself, but I personally would rather not cut an SIO cable if I didn't absolutly have to!

Thanks, Yea I decided to do just that, partly because I don't have enough spare time to look into building it correctly and also because I don't wanna get voltages or other stuff wrong. Like you say, I don't have to mess up an SIO cable either. For the sake of a small amount of money to get a manufactured one it's the best option in the end.

Tezz

 

I can confirm that you wont regret buying one from atarimax.

I bought mine about 3 months ago, and it gets lots of use.

I also love the 8meg flashcart that I bought from him, and all the free advise and support that comes when a dumb ass like me tries to use this stuff!(it's simple, but I am more simple )

[HiassofT]

If you are buying a MAX232 (clone), just have a look at the datasheets of the manufacturer (Dallas/Maxim, ST, ...).

 

Basically, the difference between the MAX232 and MAX232A is that the latter only needs 0.1uF caps instead of 1uF caps and that it's able to do 200kbps instead of 120kbps.

The MAX233(A), which is somewhat more expensive than the MAX232(A), doesn't need the external caps at all. But beware: the pinout is different.

 

So far the MAX232 type interfaces work 100% reliable with all my PCs, whereas my 14C89 based interface works only with the builtin (onboard) RS232 interfaces of my PCs and completely fail with all of my addon interface cards. So, just spend the 1-2 bucks more for a MAX232 based interface and you'll be fine.

 

so long,

 

Hias

[marquisor]

i've got a max232 cable here. is it true, that it only works with RI setting in winape? and the transfer is very likely to get instable, mostly after using disk duplication software and go back to DOS.

or is there something wrong with my cable?

it looks like the schematic big gif w/o the leds on a rasterboard. only some cables and diodes. bought on ebay in a atari 800 XL package.

Edited November 17, 2012 by marquisor

[+Larry]

I read back through the entire thread this AM, and it raises a question -- why do some 14C89 interfaces seem to work for some folks (like me) just fine, but others can only use a MAX-type IC? I've used them interchangeably over the years with many different computers (XE/XL). Is there some type of inherent instability in the SIO circuit? Seems odd since it is so (relatively) slow. Of course, many/most folks have now moved on to SIO2USB interfaces so it is a fairly moot point. But still a fair question, I think. Anyone?

 

-Larry

[Fox-1 / mnx]

why do some 14C89 interfaces seem to work for some folks (like me) just fine, but others can only use a MAX-type IC?

 

The main difference between the 14C89 and the MAX is the voltage level of the signals on the PC side. A 14C89 works at 0V / +5V levels where the MAX is using -7V / +10V (about).

 

IIRC the official PC COM-port specs expect a signal to go below 0V to register it as a "0" and +7V for a "1". That is the theory. In real life 0V and +5V is close enough to register as "0" and "1". When using a 14C89 with a low quality, non-shielded cable it may get more picky, but like you said, I also never had a single problem when using 0V / 5V levels on any AT/PC platform I ever used (which doesn't mean it isn't possible).

 

 

tl;dr:

 

A MAX is closer to the official specs