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What do we know about actual bus usage?


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#26 42bs OFFLINE  

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Posted Tue Oct 2, 2018 3:06 PM


Seems all of these details ARE documented, I just noted a tiny tidbit in the docs we have that mentions Appendix 7 holds the gory details.

 

Does this "Appendix 7" exist? I have an original Atari folder, but only appendices 2 and 5.

Do you have a link?



#27 oziphantom OFFLINE  

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Posted Wed Oct 3, 2018 12:46 AM

 

I was going to argue it from the other direction: given that the requirement is a four-byte boundary rather than an 8-byte, it doesn't necessarily have the logic to distinguish 5 4 4 4 4 4 4 4 from 5 4 4 4 5 4 4 4.

 

But, either way, since Mikey seems to access in 8-byte spurts it's bound to be one of those two patterns.

 

Re: refresh, don't forget that — 8-bit or otherwise — the Lynx is a 1989 machine. So it supports CAS-before-RAS and hidden refresh; indeed it almost certainly isn't using classic RAS-only refresh because the advantage of those two is that the row counter is inside the RAM, so that's one less thing for Mikey to keep track of. If and when more is known about Suzy, a test might be to see what the penalty is when drawing with Suzy with the display off, since Mikey won't actually strictly need to do any memory accesses.

I too was going to float the idea it does it 5 4 4 4 5 4 4 4 as a potential refinement.

Re RAS-only while that may be true, that is still an Extra Tick somewhere, its "free" in terms of 4Mhz clocks I guess, but at best it will eat a Tick.



#28 oziphantom OFFLINE  

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Posted Wed Oct 3, 2018 12:48 AM

 

Does this "Appendix 7" exist? I have an original Atari folder, but only appendices 2 and 5.

Do you have a link?

No idea. I'm the johnny-cum-lately, I only have what I can download from here. There is 1 reference to it in the TIFFs we have, but no actual scan of it in the download pack. Nor any fixes in the "errata updates" to gleam info from.



#29 42bs OFFLINE  

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Posted Wed Oct 3, 2018 5:32 AM

No idea. I'm the johnny-cum-lately, I only have what I can download from here. There is 1 reference to it in the TIFFs we have, but no actual scan of it in the download pack. Nor any fixes in the "errata updates" to gleam info from.

 

Right. I looked all the docs I have. I even found a comment about the qbert root. But no appendix 7.

I guess a lot of info got lost when Atari bought the product.



#30 oziphantom OFFLINE  

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Posted Wed Oct 3, 2018 11:49 PM

I doubt it was lost, I would imagine that all of the pages were kept and shipped to devs. While it might have been a "more complete" set rather than every dev on the planet. But I would think if one found a physical copy of the documentation in the folder it would have it. Just the person who did the scanning didn't have it. Maybe the stuff we have is the "well I don't need to look at it too much" so it stayed in the folder, while the timing stuff was kept out and "on hand" so it was lost.

 

Anybody got an account on ASSEMbler ?



#31 karri ONLINE  

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Posted Thu Oct 4, 2018 12:03 AM

I have a physical copy. As a matter of fact I signed up as an Atari developer when the Lynx first came out and got the docs. The total developers folder is actually hundreds of pages with emails and internal notes. I should really scan everything as long as the papers are readable.


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#32 42bs OFFLINE  

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Posted Thu Oct 4, 2018 12:34 AM

I have a physical copy. As a matter of fact I signed up as an Atari developer when the Lynx first came out and got the docs. The total developers folder is actually hundreds of pages with emails and internal notes. I should really scan everything as long as the papers are readable.

 

I also got the original docs. But no appendix 7. But a dozen of pages of the shifter outputs.

Ah, and found a description of algo 3.



#33 42bs OFFLINE  

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Posted Thu Oct 4, 2018 12:36 AM

Anybody got an account on ASSEMbler ?

 

No, even do not know what you mean?



#34 enthusi OFFLINE  

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Posted Thu Oct 4, 2018 12:49 AM

Audio shifter outputs? That Sounds quite interessting!

#35 42bs OFFLINE  

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Posted Thu Oct 4, 2018 1:03 AM

Audio shifter outputs? That Sounds quite interessting!

Not really. It is a long list of values of the LFSR.  A small program can output these easily. At the time I got the docs I did wonder, why on earth they fill pages with this ...



#36 Turbo Laser Lynx OFFLINE  

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Posted Thu Oct 4, 2018 1:12 AM

I have a physical copy. As a matter of fact I signed up as an Atari developer when the Lynx first came out and got the docs. The total developers folder is actually hundreds of pages with emails and internal notes. I should really scan everything as long as the papers are readable.

 

Scanning is really a pain  :-o  if there's something relevant in there, some Hi-Res photos would be a nice start, it's so much faster and less tedious. I'd say even phone cameras takes pretty good fotos of documents these days.



#37 oziphantom OFFLINE  

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Posted Thu Oct 4, 2018 1:23 AM

ASSEMbler is a forum of people who have and collect devkits. But seeing as we have two copies of the "docs" here, no need..

 

Karri does yours have Appendix 7?

 

We can start a get Karri a HP ScanJet fund. I bought an old one off Ebay and still working through all my books. It has a feed tray and it does duplex scanning, with OCR software, so I just cut my books up, place a stack of pages in the tray, hit scan. and it does it.. mostly by it self. you get the odd paper jam, grabs a couple of pages at once etc. Slow and steady.



#38 karri ONLINE  

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Posted Thu Oct 4, 2018 1:28 AM

My copy is buried somewhere in the basement. My guess is that it does not have more than what 42bs has. The paper size is also quite large so using a camera may be the most sensible recording device.



#39 enthusi OFFLINE  

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Posted Thu Oct 4, 2018 3:45 AM

Not really. It is a long list of values of the LFSR.  A small program can output these easily. At the time I got the docs I did wonder, why on earth they fill pages with this ...

Aside from emulators there is no (detailed) information on those available. At least none that I know of?



#40 42bs OFFLINE  

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Posted Thu Oct 4, 2018 4:03 AM

http://www.monlynx.d...lynx7.html#_71:

 

"12 bits of shift register and 9 bits of tap selector. 9 outputs of the 12 bit shift register are individually selectable as inputs to a large exclusive or gate. The inversion of the output of the gate is used as the data input to the shift register. This is known as a polynomial sequence generator and can generate waveforms that range from square (for musical notes) to pseudo random (for explosions). This same inverted output is taken from the exclusive or gate and sent to the waveshape selector."

 

So (from heart): If the selector is 1 ($FD21), than you get a simple square wave with half the frequency:

0000b => 0001b => 0010b => 0101b ...



#41 sage OFFLINE  

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Posted Thu Oct 4, 2018 5:16 AM

Aside from emulators there is no (detailed) information on those available. At least none that I know of?

Chipper writes a list in its folder upon first start.



#42 Turbo Laser Lynx OFFLINE  

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Posted Thu Oct 18, 2018 1:36 PM

Here's a quote about appendix 7 at least:

https://archive.org/...9_1989_djvu.txt

 

it says:

1.3 Mikey Bus Controller 

The Mikey bus controller has 3 requestors for its bus, the CPU, the video, and 
refresh. After system reset, the video and refresh are disabled and the CPU request is 
on. The CPU, when appropriate, can enable the video and refresh circuits to request 
the bus. See the state machine description (appendix 7) for cycle by cycle details of 
bus acquisition. 

 

This is like a treasure hunt! :D


Edited by Turbo Laser Lynx, Thu Oct 18, 2018 1:38 PM.


#43 jum OFFLINE  

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Posted Mon Mar 25, 2019 8:16 AM

From my one test on Handy vs real hardware, seems the real hardware is faster:

 

http://atariage.com/...r/#entry3910354

 

(For this case at least - draw background clear sprite and draw full screen sprite).

 

 

 






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