Atari 800 SIO mod

[cathrynm]

I'm going over the instructions here http://sio2sd.gucio.pl/wiki/HighSpeed_en except I have Atari 800.  It looks like C184 and C185 should be removed, so I think that's clear.  From this it looks like there already is a 4.7K resistor from 5V to Data Out on the 800 though?  I think maybe I don't need this.  Has anyone done this?

[BillC]

52 minutes ago, cathrynm said:

From this it looks like there already is a 4.7K resistor from 5V to Data Out on the 800 though?  I think maybe I don't need this.  Has anyone done this?

Those resistors from +5V to the SIO signals are pull-up resistors, don't remove any of them. These signals are pulled low by the source ICs.

You do probably want to remove the capacitors on the DATA-IN, DATA-OUT and COMMAND signals to improve higher speed SIO operations, according to the schematic these would be C184/C185/C188.

Edited June 5, 2021 by BillC

[cathrynm]

20 minutes ago, BillC said:

Those resistors from +5V to the SIO signals are pull-up resistors, don't remove any of them. These signals are pulled low by the source ICs.

You do probably want to remove the capacitors on the DATA-IN, DATA-OUT and COMMAND signals to improve higher speed SIO operations, according to the schematic these would be C184/C185/C188.

Wasn't considering removing the resistors.  Instructions talk about adding another one from data-out to 5V, which I think now, maybe a XL issue only.

[griff3125]

The original 800 is fine, I know on my 1200xl I had to do the 5vt line mod and the s-video mod, probably the same for the 800xl.

 

[Gunstar]

I haven't done a thing to my Atari 800's SIO (except add another), and I've had no problems using HS SIO all the way up to divisor 0 speeds. Though I do have the Incognito with it's HS SIO abilities set, you just may need a high-speed SIO patched OS B. If resisters on the port were an issue, it would still cause speed issues even with patched OS's (or enhanced BIOS's), which I would think the Incognito proves is not the case.

Edited June 5, 2021 by Gunstar

[Mazzspeed]

56 minutes ago, Gunstar said:

I haven't done a thing to my Atari 800's SIO (except add another), and I've had no problems using HS SIO all the way up to divisor 0 speeds. Though I do have the Incognito with it's HS SIO abilities set, you just may need a high-speed SIO patched OS B. If resisters on the port were an issue, it would still cause speed issues even with patched OS's (or enhanced BIOS's), which I would think the Incognito proves is not the case.

I removed all the capacitors from the SIO port of my 600XL, the improvements were immediately evident at any HSIO speed below divisor 5 and I'm running an U1MB.

 

What's this 5v mod?

Edited June 5, 2021 by Mazzspeed

[flashjazzcat]

47 minutes ago, Mazzspeed said:

What's this 5v mod?

The 1200XL has a current limiting resistor on the SIO 5V pin which needs replacing with a 0 Ohm resistor or jumper for peripherals without external power. No other models need this modification, AFAIK.

[Mazzspeed]

44 minutes ago, flashjazzcat said:

The 1200XL has a current limiting resistor on the SIO 5V pin which needs replacing with a 0 Ohm resistor or jumper for peripherals without external power. No other models need this modification, AFAIK.

Cheers FJC! Thanks for the reply.

[+DrVenkman]

4 hours ago, cathrynm said:

I'm going over the instructions here http://sio2sd.gucio.pl/wiki/HighSpeed_en except I have Atari 800. 

My 800's work great all the way to POKEY divisor 0. Have you actually tested your 800 at high speed and an appropriately-modded high-speed OS? 

[cathrynm]

Just now, DrVenkman said:

My 800's work great all the way to POKEY divisor 0. Have you actually tested your 800 at high speed and an appropriately-modded high-speed OS? 

I have tried it, and it works, mostly.  Just sometimes it gets flakey, and I'm not sure why.

[+DrVenkman]

Just now, cathrynm said:

I have tried it, and it works, mostly.  Just sometimes it gets flakey, and I'm not sure why.

What are you using as the source for serving up the files to your 800?

[cathrynm]

Just now, DrVenkman said:

What are you using as the source for serving up the files to your 800?

I have Fujinet, APE, and an SIO2SD.  And I've been monkeying with various combinations, of plugging in one, two, all three, and the Lotharek Spliter.

[Mazzspeed]

I swear my FTDI based FL232 board is a Chinese clone. I'd buy another, but there's no way of telling if the new one also won't be a clone. FTDI really needs to do something about that beyond just making the chip unusable via Windows drivers.

 

My speeds are good, but not what they should be and I don't get any errors.

[Faicuai]

1 hour ago, cathrynm said:

and the Lotharek Spliter

Gunstar experience is mine, too. No modification (of any kind) needed to run Div 1/0 on my 1983 and 1980 (040-0077) 800.

 

What is the max. sustained speed you are getting on your 800 with Lotharek SIO-hub? (I have it, too)

[+DrVenkman]

You need to be running a high-speed OS or something like Jon's Incognito firmware with PBI BIOS enabled and HSIO turned on, combined with a rock-solid wifi connection for your Fujinet, or load directly from the SD card; if using an external program like APE or Respect, you need to have a stable OS that isn't overloaded, and a good interface device. Although this machine has an Incognito in it, it does not have any modification whatsoever to the SIO signal chain.

 

For instance, I just flashed the entire 512K Incognito ROM on one of my 800's through RespeQt on my Win10 box using a genuine FTDI serial-to-SIO interface device. 

 

[Gunstar]

@cathrynm

 

Even though my Atari 8-bit modifications & upgrades list, in my signature below, include HS SIO on both my 800 and 1200XL, it's referring to the OS's or BIOS's in them giving the ability, not fixes to the SIO (even though the 1200XL did receive SIO fixes).

Edited June 7, 2021 by Gunstar

[Mazzspeed]

9 hours ago, DrVenkman said:

You need to be running a high-speed OS or something like Jon's Incognito firmware with PBI BIOS enabled and HSIO turned on, combined with a rock-solid wifi connection for your Fujinet, or load directly from the SD card; if using an external program like APE or Respect, you need to have a stable OS that isn't overloaded, and a good interface device. Although this machine has an Incognito in it, it does not have any modification whatsoever to the SIO signal chain.

 

For instance, I just flashed the entire 512K Incognito ROM on one of my 800's through RespeQt on my Win10 box using a genuine FTDI serial-to-SIO interface device. 

 

May I ask if you remember where you got your FTDI serial to USB board from if it's indeed genuine?

[+DrVenkman]

7 hours ago, Mazzspeed said:

May I ask if you remember where you got your FTDI serial to USB board from if it's indeed genuine?

I got it 6 or 7 years ago here on the forum from a fellow who was selling adapters built right into a custom PCB designed to fit inside an SIO plug housing. It has a mini USB connector on what would be the cable end of the connector. He was buying bare chips, not prebuilt boards. You can buy prebuilt genuine FTDI based USB-serial interface boards from Sparkfun. That’s what is used in the 1088XEL design. 

[Mazzspeed]

1 minute ago, DrVenkman said:

I got it 6 or 7 years ago here on the forum from a fellow who was selling adapters built right into a custom PCB designed to fit inside an SIO plug housing. It has a mini USB connector on what would be the cable end of the connector. He was buying bare chips, not prebuilt boards. You can buy prebuilt genuine FTDI based USB-serial interface boards from Sparkfun. That’s what is used in the 1088XEL design. 

Awesome, thanks for the information. I'll look into Sparkfun as I swear this board I have here is counterfeit.