Falcon Nemesis rewire with questions

Hardware, coding, music, graphic and various applications

Moderators: Mug UK, lp, [ProToS], moondog/.tSCc., Moderator Team

User avatar
Robson
Atari Super Hero
Atari Super Hero
Posts: 694
Joined: Sun Feb 19, 2006 7:03 am
Location: London

Falcon Nemesis rewire with questions

Postby Robson » Mon Mar 06, 2017 9:41 am

Hi,

I had this mobo for a while and recently spent some time to rewire it completely.
I read previous posts so as Simbo's guide but have few things I need confirmation, which I thank you in advance.

This is the board as it was. Gluegun and extensions, etc.

Nemesis_mess_Robson.jpg


Rewired, using mini coax and copper foil to add extra shielding. The board is not in yet fitted into it's place. Also added socket for nvram and a jumper for the fan (the long cable there for testing only). I didn't use the red and orange wires.

Nemesis_rewired_Robson.jpg


My questions are:
1. When I switch the falcon on, I need to hit reset, sometimes 2 or more times to get the system booting. Is this normal?

2. I can see acceleration when running the bench, however the nemesis.prg or acc shows no difference even if acceleration seems to be ON.

3. The HRTC mode gives me a very noisy output on my tft. I'm not too keen on this mode but would be good to know if this is an issue or something to be fixed (picture will come tonight)


Image is from Simbo's guide but I've never seen the HI or LOW selected, even if there is acceleration.
NEM_ACC.GIF


NEM_BENCH - NEM_OFF

Nemesis_off_Robson.jpg


NEM_BENCH - NEM_HI

Nemesis_HI_Robson.jpg


Gembench 6 (off/on)

gb6.jpg


Thanks.
You do not have the required permissions to view the files attached to this post.
------------------------------------------------
https://tercsirobi.000webhostapp.com
------------------------------------------------

User avatar
catmando
Atari Super Hero
Atari Super Hero
Posts: 962
Joined: Tue Jan 24, 2006 9:56 pm
Location: London, UK

Re: Falcon Nemesis rewire with questions

Postby catmando » Mon Mar 06, 2017 6:54 pm

1. I don't think this is normal, haven't powered mine on for a while but I don't remember having this issue.
2. I haven't tried this before, will let you know what happens when I give it a go.
3. What is HRTC mode?
Atari Falcon Tos 4.04 | 14mb | IDE CF 2GB
Atari STE Tos 1.62 | 4mb | HxC Slim SD 8GB
Atari STE Tos 1.62/2.06 | 4mb | Floppy A-B Mod | IDE SD 4GB
Atari STFM
Android Devices (Running Hataroid and SToid)

Atari Forum Wiki - Use it before asking

User avatar
dhedberg
Atari Super Hero
Atari Super Hero
Posts: 718
Joined: Mon Aug 30, 2010 8:36 am
Contact:

Re: Falcon Nemesis rewire with questions

Postby dhedberg » Mon Mar 06, 2017 8:19 pm

Robson wrote:My questions are:
1. When I switch the falcon on, I need to hit reset, sometimes 2 or more times to get the system booting. Is this normal?

Did this not occur before the rewiring and NVRAM replacement?
Try to put some pressure on the NVRAM chip and see if it helps. If it does not have good contact with the motherboard the Falcon will not boot. If it helps, its probably bad soldering joints or just a bad socket if you installed a socket there.
I used to have some problems with resets on one of my Falcons, but after replacing all the electrolytic capacitors on the motherboard, and the PSU with a picoPSU, all problems I experienced are gone.

Robson wrote:2. I can see acceleration when running the bench, however the nemesis.prg or acc shows no difference even if acceleration seems to be ON.

I've got the Nemesis installed in one of my Falcons and I've also developed the Nemesis Indicator software that can be used to control it (get it from nb.atari.org). The current mode of the Nemesis cannot be detected by accessing the hardware unless you measure the bus speed or similar. All Nemesis tools rely on the software that is actually changing the mode of the Nemesis to also update the NSPD cookie. If the cookie is not updated or the cookie is not installed, the Nemesis software will not show the correct mode. So, nothing wrong with the hardware, most likely just a software issue. If you use the original software that comes with the Nemesis, NEMESIS.PRG should be executed first, followed by for instance NEM_HI.PRG. After that, all Nemesis software should show the right mode. At least Nemesis Indicator will.

Robson wrote:3. The HRTC mode gives me a very noisy output on my tft. I'm not too keen on this mode but would be good to know if this is an issue or something to be fixed (picture will come tonight) [/b]

What's HRTC? High Resolution True Color mode?
Daniel, New Beat - http://newbeat.atari.org. Like demos? Have a look at our new Falcon030 demo MORE.

User avatar
Robson
Atari Super Hero
Atari Super Hero
Posts: 694
Joined: Sun Feb 19, 2006 7:03 am
Location: London

Re: Falcon Nemesis rewire with questions

Postby Robson » Tue Mar 07, 2017 12:13 am

Thank you both.

1. It might be the reset switch itself too, I have to have a closer look.

2. You're right if I change the order, I can see the mode changing. thanks for pointing this out.

3. Yes the 320x480 override mode I'm talking about. I'm not using it just tested and I don't like what I see there.

hrtc.jpg


-------------------------------
From doc:

[H]igh [R]es [T]rue [C]olour

HRTC.PRG should reside in your auto folder after NVDI if it is installed.

This patch program provides access to the quarter pixel, true colour VGA
modes made possible by Nemesis. It does this by patching the 320 x 480
mode to 640 x 480 - select 40 column, double line off and true colour from
the dialogue provided by the desktop Set Video dialogue.

Users of Videlity do not require this patch
-------------------------------
You do not have the required permissions to view the files attached to this post.
------------------------------------------------
https://tercsirobi.000webhostapp.com
------------------------------------------------

User avatar
dml
Fuji Shaped Bastard
Fuji Shaped Bastard
Posts: 3472
Joined: Sat Jun 30, 2012 9:33 am

Re: Falcon Nemesis rewire with questions

Postby dml » Tue Mar 07, 2017 10:01 am

The problem shown on your TFT for HRTC mode doesn't look like the kind of issue that was most commonly seen - slow RAM sticks. Usually if the bus was boosted far enough (25MHz+) the 70ns ram would not keep up and you'd get vertical columns of sparkling noise. The next step was to find faster ram sticks (i.e. 60ns or just try different ones until it works).

This looks more like some kind of video linewidth problem.
- Does it jump around constantly or is it stable?
- Does it only do this in the HRTC-patched video mode? If you then change mode to 256 colours, does the issue persist?
- Does the machine crash or become flaky when this occurs? If not, it's an issue limited to the Videl circuit or the TFT.
- Have you tried on a different monitor?

Problems with reset are fairly common and can be worsened by adding modifications / boosters. It may be related to voltage drop and ripple but I haven't looked at it properly myself. One of my Falcons has this issue. Seems like Daniel had success with recapping.

User avatar
Robson
Atari Super Hero
Atari Super Hero
Posts: 694
Joined: Sun Feb 19, 2006 7:03 am
Location: London

Re: Falcon Nemesis rewire with questions

Postby Robson » Tue Mar 07, 2017 10:34 am

I've uploaded the video here (will be removed later)

https://www.dropbox.com/s/k6m5kk4criclx ... 4.MTS?dl=0

It's video issue, the machine is still responsive and I can change the resolution back as you can see. This is a multisync monitor (NEC LCD400V) can eat almost everything I give.
I can try on a ptc1426 later but probably the result will be the same. My dell tft can't edal with the signal.
------------------------------------------------
https://tercsirobi.000webhostapp.com
------------------------------------------------

User avatar
dml
Fuji Shaped Bastard
Fuji Shaped Bastard
Posts: 3472
Joined: Sat Jun 30, 2012 9:33 am

Re: Falcon Nemesis rewire with questions

Postby dml » Tue Mar 07, 2017 11:12 am

Actually, having looked at the vid - it could still be a ram speed problem. It doesn't look like the typical version of it at 24mhz, but might be a more extreme version of it with HRTC mode specifically. When the ram can't keep up, the Videl is first to be starved. The CPU seems to manage despite having lower priority - probably different type of acknowledge signals.

Unfortunately it's not that easy to confirm on a Falcon unless you have a custom memory board which accepts SIMMs (or spare Falcon memory boards lying around).

So check the speed of the ram you have. If it is marked 70ns its probably too slow in any case.

If you do have a SIMM-based memory board, you could try the following:

1) swap the SIMMs for alternates, to see if the problem gets better or worse. any increase or decrease in the jumpy/glitchy effect is indicative that it is a ram-speed issue. if you get no perceptible change, or new columns of noise appear on top of it, then its (probably) separate from a ram speed issue.
2) if there are multiple SIMMs on the same board, take both out and put one back at a time, and compare results. each SIMM tends to have a different 'top speed' so they may give different results if its a ram speed issue.

Other than that, you could inspect the area between nemesis and Videl (and combel), and shielding involved there. If you can affect the problem by moving things or changing the shielding arrangement it may give you more info. But be careful - fiddling with wiring and shielding its an easy way to accidentally kill the board.

User avatar
Robson
Atari Super Hero
Atari Super Hero
Posts: 694
Joined: Sun Feb 19, 2006 7:03 am
Location: London

Re: Falcon Nemesis rewire with questions

Postby Robson » Tue Mar 07, 2017 1:02 pm

Thanks for the tip.
On the images the green ram board has a simm slot so that can easily be replaced. However for the video I swapped out the ram for another 14mb module. The black one available on AA forum. I am not at home now but will update post with that info later.

I will double check the shields and there is also a way to separate combel and videl clocks using the red wire of nemesis to feed the top pad of the resistor (where the brown goes bottom pad) but I am not sure I want to do that because as I mentioned I only tried out this resolution to test and see what is achievable.
The main thing for me is to find the startup bug. So I will sniff around the reset and caps first.
------------------------------------------------
https://tercsirobi.000webhostapp.com
------------------------------------------------

User avatar
Atari030
Atari Super Hero
Atari Super Hero
Posts: 588
Joined: Mon Feb 27, 2012 6:14 am
Location: Melbourne, Australia

Re: Falcon Nemesis rewire with questions

Postby Atari030 » Tue Mar 07, 2017 10:33 pm

Daniel and Doug are on the money, reset cap. First time I saw that one it had me scratching my head for bit. 20c fix at least.

Rustynutt
Captain Atari
Captain Atari
Posts: 478
Joined: Wed Mar 21, 2012 7:38 am
Location: Oregon
Contact:

Re: Falcon Nemesis rewire with questions

Postby Rustynutt » Tue Aug 01, 2017 9:57 pm

Here's and archive Simbo posted a while ago. Lots of Nemesis info.
You do not have the required permissions to view the files attached to this post.

User avatar
viking272
Captain Atari
Captain Atari
Posts: 324
Joined: Mon Oct 13, 2008 12:50 pm
Location: west of London, UK

Re: Falcon Nemesis rewire with questions

Postby viking272 » Sun Dec 31, 2017 1:15 am

Rustynutt wrote:Here's and archive Simbo posted a while ago. Lots of Nemesis info.

Thanks for this info.

I also found some details from Simbo in a personal mail...I couldn't see these items in the archive file. I presume they are sensible things to do?

    o replace the rom with a 90ns tos 4.04 eprom with a window {always better quality than otp chips without a window}
    o use 60ns fpm ataris own board is 80ns ram and is crap in wait state
    o check the shorting pads are set right for rom type and wait state {on the left of the atari falcon board
    o change all wires on the nemesis for 50R coax
    o work slowly!

Rustynutt
Captain Atari
Captain Atari
Posts: 478
Joined: Wed Mar 21, 2012 7:38 am
Location: Oregon
Contact:

Re: Falcon Nemesis rewire with questions

Postby Rustynutt » Mon Jan 01, 2018 1:32 am

Yes, looks good. If there is enough RAM, running TOS in RAM could save having to burn another ROM. Definitely use faster memory. I used Coax to the SDMA CLKIN and had good results using a terminating resister at that point. This was with an Afterburner and Mighty Sonic. Have read using a cap there on the STD CPU works well. Have read a lot of "horror" stories, careful work and the FO4 buffer never gave me problems. I don't think the wait state matters if you run TOS in RAM, other than at boot.

User avatar
viking272
Captain Atari
Captain Atari
Posts: 324
Joined: Mon Oct 13, 2008 12:50 pm
Location: west of London, UK

Re: Falcon Nemesis rewire with questions

Postby viking272 » Thu Jan 25, 2018 10:13 pm

Thanks for these tips Rustynutt.

@Robson, did you get anywhere with troubleshooting your Nemesis issues? Did a new RAM chip help you out?

User avatar
Robson
Atari Super Hero
Atari Super Hero
Posts: 694
Joined: Sun Feb 19, 2006 7:03 am
Location: London

Re: Falcon Nemesis rewire with questions

Postby Robson » Thu Jan 25, 2018 11:11 pm

Unfortunately no, this board has a +5v/gnd short now, I am working on that slowly as my time allows.
------------------------------------------------
https://tercsirobi.000webhostapp.com
------------------------------------------------


Social Media

     

Return to “Professionals”

Who is online

Users browsing this forum: No registered users and 5 guests