Jump to content
IGNORED

19,200 on an 850 UltraSpeed Possible?


Kyle22

Recommended Posts

I had a thought about the 850. It's a simple bit-banger, so what are the limits of the hardware? Is it possible to kick up the baud rate between the 850 and the computer to 38,400?

 

Even if this involved changing to a faster crystal, it would still be a great thing.

 

Ideas, Thoughts...?

 

 

  • Like 2
Link to comment
Share on other sites

I had a thought about the 850. It's a simple bit-banger, so what are the limits of the hardware? Is it possible to kick up the baud rate between the 850 and the computer to 38,400?

Even if this involved changing to a faster crystal, it would still be a great thing.

 

 

The 850 hardware is very similar to the 1050. Same CPU at the same clock, same RIOT chip used for the data ports. There is technically no reason why the 850 couldn't bitbang as fast as the 1050 USD or a Happy 1050. One relevant issue is serial input that is asynchronous, a complication you don't have on the 1050. And concurrent I/O is normally transparent anyway (the module just mirrors the serial input into the SIO bus). But say, for something like printer output, it shouldn't be a problem.

Edited by ijor
Link to comment
Share on other sites

I just wish someone would come out with a new run of MIO type devices. (I have a 256k that I'm using and somewhere in storage I have a 1mb, both original ICD units).

 

But the CSS Black Box or something else would be great. Even a PBI "serial/parallel" (or even serial only) device.

 

Any of the "more technically endowed" able to speculate how fast of a serial port a PBI device could theoretically handle?

Link to comment
Share on other sites

I just wish someone would come out with a new run of MIO type devices. (I have a 256k that I'm using and somewhere in storage I have a 1mb, both original ICD units).

 

But the CSS Black Box or something else would be great. Even a PBI "serial/parallel" (or even serial only) device.

 

Any of the "more technically endowed" able to speculate how fast of a serial port a PBI device could theoretically handle?

 

http://www.rasterline.com/mio.html

Link to comment
Share on other sites

 

 

The 850 hardware is very similar to the 1050. Same CPU at the same clock, same RIOT chip used for the data ports. There is technically no reason why the 850 couldn't bitbang as fast as the 1050 USD or a Happy 1050. One relevant issue is serial input that is asynchronous, a complication you don't have on the 1050. And concurrent I/O is normally transparent anyway (the module just mirrors the serial input into the SIO bus). But say, for something like printer output, it shouldn't be a problem.

 

I'd be happy with 19,200, but even 38,400 is less than the ~52K that the USD can reliably do.

Link to comment
Share on other sites

 

I'd be happy with 19,200, but even 38,400 is less than the ~52K that the USD can reliably do.

 

As I said, hardware wise it shouldn't be a problem at all for the 850 to do the 52K USD. All you need is just a custom ROM, assuming there is enough space. But again, that won't work for serial input without some kind of redesign.

 

Link to comment
Share on other sites

I had a thought about the 850. It's a simple bit-banger, so what are the limits of the hardware? Is it possible to kick up the baud rate between the 850 and the computer to 38,400?

 

Probably not. For that, you need to know how the 850 works. If you enable the concurrent mode, then the serial speed is really up to Pokey. What the 850 does in this case is that it samples the input serial line, and mirrors the output, 1:1. It does this by polling the input line with the CPU, and simply placing the same signal at the output. Thus, the bitrate is limited by the (half the) highest frequency the 1Mhz CPU within the 850 can sample the data.

 

There is a good reason why the 850 is limited to 9600 baud. If you want higher serial speeds, a direct upconverter from +5V to +/-12V is probably the better choice, such as a pair of 1488 and 1489 chips. Problem is to get RTS/CTS hardware handshaking working.

Link to comment
Share on other sites

According to the manual on Atarimania the ICD P:R: Connection is capable of 19,200, but they are fairly rare.

 

a8maestro at one time sold a 19.2k modified version of the R-VerterII, but I don't believe he still does. He is registered on AA but hasn't been logged in since last April.

 

I did find the following page from his site where information/schematics about the R-Verter I and II are available. The R-Verter II text file says it was capable of 19.2k, 38.4k was tested but had too many errors.

http://atari.a8maestro.com/info/8ball/ballho.htm

Edited by BillC
Link to comment
Share on other sites

Before SIO2PC existed I used a P:R: Connection / null modem cable / PC clone to transfer files back and forth via zmodem. 14.4k worked sort of, but there were just too many errors and retries that running at 9600 was actually faster in the long run. I wonder if I had used a shorter serial cable if I would have had different results.

Link to comment
Share on other sites

Yes, there is a discrepancy in the documentation. This has been the main thing that has been holding me back on this. I love the R:Verter. It is simple, and it's just a level converter. PoKey does it all, and it works. Simple is best, BUT, we need to make it just a little more complicated.

 

How about we add some more level converters so we can monitor and control RTS/CTS, DSR.DTR. CD, etc.

Let's attach these new i/o pins to a joystick port.

 

Write a handler that does buffering and RTS/CTS control, and that's the perfect example of minimalist design.

 

Edit: And it would do 19,200, 38,400 or better...

Edited by Kyle22
  • Like 1
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...
  • Recently Browsing   0 members

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