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Old 18 January 2021, 07:17   #1
bender
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Amiga 4000T and Zorro 3 Boards

Hello!


I hope someone can help. I have an Amiga 4000T with the following symptoms:


If I add a Picasso IV, it is not recognized at all. It does not appear on the early boot.


If I add a Deneb in Zorro 3 mode, it is seen in the early boot, but does not work. I cannot see the unit that it mounts (with Poseidon and other software to install) and I cannot see the "Deneb" animation that is normally shown at the start.


Both cards (Picasso IV and Deneb work perfectly as they are in a 4000D).


I have been visually inspecting the 4KT, checking continuity of the Z3 pins and nothing seems to be wrong, but then I realized that P701 (the "Arbiter" according the schematics on this site: https://www.amigawiki.org/doku.php?i...ice:schematics A4KT PDF Page 13), has clear signs of rework, maybe even being replaced. I can clearly see the solder is different and there are some solder blobs on the pins (no bridges though).


So my question is, could a bad P701 cause the issues I am seeing? And if it is defective, is it possible to get a replacement for that chip? Maybe a fix has was attempted to try and fix the issue with no success. It's been like this since i bought it years ago.


In the schematics P701 says "P16R4-15" and the chip in my machine says "TI16R4-15 58A8KKWF". Also, it says "PAL" in the schematics. I think those are programmable chips right?


I appreciate any help you can provide.


Thanks!
Efrén
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Old 19 January 2021, 02:21   #2
grelbfarlk
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Yes that is a programmable chip that anyone with a burner should be able to replace for you. The PAL contents are on that same site here:
https://www.amigawiki.org/doku.php?i...s:pld_download
It stands to reason if someone screwed with that it might be worth replacing it, or at least remove it and verify the contents-not that this would necessarily tell you anything unless it was totally unreadable or failed verification.
Do you have any Zorro-2 cards you can test with?
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Old 20 January 2021, 05:08   #3
bender
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Hello!

I did not know those files were available. Thanks!

Yes I do have one X-Surf (first version). I think that is a Zorro II card. Also, I haven't tested the Deneb in Zorro II mode. I'll try those 2 during the weekend.

Regards,
Efrén
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Old 20 January 2021, 12:31   #4
hooverphonique
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That PAL/GAL could have been changed as part of an upgrade of Buster to rev 11, though, as there allegedly is a change required in it when upgrading buster from 9 to 11.
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Old 20 January 2021, 15:42   #5
Hedeon
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Didn't A4000(T)s come with 11 standard?
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Old 20 January 2021, 19:44   #6
DarrenHD
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Quote:
Originally Posted by Hedeon View Post
Didn't A4000(T)s come with 11 standard?
Yes it did. A4000T that is, so that should not have been the reason that chip was tampered with.

I had an A4000T with similar symptoms and it turned out to be a bad solder on one of the legs of the Bridgette chip (from the factory). Worth inspecting. Fixed that and Zorro cards worked again.
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Old 21 January 2021, 04:51   #7
bender
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Hello again

The Buster is 11, and shows no signs of rework (not that I am an expert but most of the times you can tell).

I checked Bridgette but I can see nothing bad or stange with the solder. I have 4X magnifying glasses so that's the limit of what I can see. They help a lot actually.

Thanks guys! I'll post back when I test with ZII cards.

Regards,
Efrén
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Old 22 January 2021, 08:53   #8
bender
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Hello again

Today I had a chance to continue with this. There is anothe issue that bothers me and it is that the LED for the internal speaker is always on, regardless of the speaker switch. The speaker does reproduce sound (or not) depending on the switch, but the LED does not care, it remains on all the time.

While testing for this, I noticed that there is only 16.9 ohms resistance between the 5V rail and Ground. Sounds low to me. The multimeter in continuity mode even beeps when I test 5V and Ground, and not a short beep that quickly stops. It can continue forever apparently.

Isn't that a short between 5V and GND? If so, how come the computer can boot and apparently works fine? (except the zorro problems I mentioned above, of course)

What am I missing here?

Thanks!
- Efrén
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Old 23 January 2021, 00:10   #9
Matt_H
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Quote:
Originally Posted by bender View Post
Today I had a chance to continue with this. There is anothe issue that bothers me and it is that the LED for the internal speaker is always on, regardless of the speaker switch. The speaker does reproduce sound (or not) depending on the switch, but the LED does not care, it remains on all the time.
My 4000T does that, too. I *think* it's normal. I've owned the machine since 2004 and I don't remember it ever behaving differently. My memory could be wrong, though.
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Old 23 January 2021, 05:45   #10
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My A4000T also measures about 16.9 Ohms between +5V and GND. This is because there are lots and lots of resistor (networks) and resistances in parallel between the two.
I think the A4000T has some funny Zorro issues. For mine, the cards can only be installed "outside in" to be recognized. I.e., I have to use slots 1 and 5 first, then 2 and 4, and only then cards in the middle slot are recognized...
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Old 24 January 2021, 06:08   #11
bender
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Quote:
Originally Posted by Matt_H View Post
My 4000T does that, too. I *think* it's normal.

Yeah... I checked with a friend who has one and his 4KT does the same thing too so... it is either its normal behavior or a very common failure



Thanks!
- Efrén
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Old 24 January 2021, 06:12   #12
bender
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Quote:
Originally Posted by torsti76 View Post
This is because there are lots and lots of resistor (networks) and resistances in parallel between the two.

Thanks! Yes it makes sense. I wish I had more knowledge on this matters but well, I'm learning



Quote:
Originally Posted by torsti76 View Post
I think the A4000T has some funny Zorro issues. For mine, the cards can only be installed "outside in" to be recognized. I.e., I have to use slots 1 and 5 first, then 2 and 4, and only then cards in the middle slot are recognized...

That is weird... I guess I'll try that too. Hopefully tomorrow I'll have some quiet time to swap cards and test different things.


Thanks!
- Efrén
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Old 24 January 2021, 12:11   #13
Kin Hell
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Quote:
Originally Posted by torsti76 View Post
My A4000T also measures about 16.9 Ohms between +5V and GND. This is because there are lots and lots of resistor (networks) and resistances in parallel between the two.
I think the A4000T has some funny Zorro issues. For mine, the cards can only be installed "outside in" to be recognized. I.e., I have to use slots 1 and 5 first, then 2 and 4, and only then cards in the middle slot are recognized...
Back in my A4KT days, I remember she was very picky when populating Slots. I'd bought the Board from Marcin in Poland & thought it was a rogue board I'd picked up....

The A4KT was the only model to have Dual Extended Video Slots. The A4KD had one & the 3000's had a plain vanilla Video Slot. - Extended was for the AGA Chipset.

Final configuration for me was PIV, Mediator with Voodoo, Ethernet & Spider USB, Kickflash, Z3 Fastlane & Prelude soundcard. Fastlane would only work in Slot 4 with Prelude in 2. The Kickflash sat in slot 3, I wanted it in 2 but everything fell apart putting the Z3 in....

I had pics of my A4KT but can't put my hands on them right now. - I miss her!
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Old 23 February 2021, 09:52   #14
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I have an A4000T with the TekMagic (ultrasound) 68060 board in it. It does get picky about expansion slots.

I am chasing a bug of possible long-standing with regards to 68040/68060 CPU bus behavior and Zorro II (16-bit) resources, and it could impact other expansion cards. If you can make Setpatch not set the data cache on (an option on the command's line) and behavior improves, try either the original v37.4 68040.library (uses conservative settings, and doesn't allow burst to Z2), or use the MuLibs 040/060 libraries (as applicable) and MuSetCacheMode tool to disable the entire 8M z2 address range (address 00200000 and size 00800000 for test). If the CPU is allowed to do a burst read or write against a peripheral in that space, unexpected results can happen when 4 longword accesses hit a board's interface registers, and trigger something they shouldn't, but 16-bit Zorro cards in the Z2 'big' 8M space may get set incorrectly, and the CPU tries to burst against it. I've already ID'd lockups or crappy performance happen with 16-bit FastRAM and Copyback/Writethrough burst happening against them (A2091's FastRAM and a GVP HC8's FastRAM, for example). I've already looped in a few CPU library maintainers on the topic. MuLubs has a few manual options including the one above that can already address it. Some trial and error may be needed to match it to a custom system.
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Old 23 February 2021, 16:56   #15
gdonner
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I wonder if any of these issues are potentially related to what IComp and Dave Haynie are attempting to resolve in Buster v12 (below)?

"During the interview of the Amiwest event, we've announced the "Buster-12" project, which will begin before Christmas of this year. In cooperation with Commodore chip designer Dave Haynie, we're developing a bug-fixed version of the Buster chip that will allow more than one DMA bus master card and that will fix other known bugs of the previous "best" Version 11 of the chip. The product, which plugs into the socket of the Super Buster of an A3000 or A4000 computer, will presumably be available in the second half of 2021."

https://icomp.de/shop-icomp/en/33/it...d-of-2020.html

Last edited by gdonner; 23 February 2021 at 18:33.
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Old 25 February 2021, 02:01   #16
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One of the outstanding issues we need some hardware logic pros on is the 68040/68060 reading the nibble bits of hardware expansion cards, particularly the Zorro II cards. Some cards don't mind the way the CPUs access their registers, some balk at the read/write. To my best understanding, the CPUs all the way up to 68030 will read 16-bits or will 'bus-size', but when you get to the 68040 and 68060, the boards get hit with a 32-bit read no matter what you do. I can take a GVP HC8 w/4MB and drop it in my Buster 11 '030 A3000 and it's happy. I drop it in my A4000T a second later, and the DPRC is read fine, but the 4MB RAM reports 'BAD'. Beside taming the cache/burst item I noted above (not an issue during autoconfig - data cache is off), I don't know what might be possible with Buster, other than the note that Z2 speeds on a Buster are 2/3 of actual Zorro II in a native 68000 system.

Buster has some problems with timing that he mostly fixed with the last -11, but with modern FPGA logic speeds well ahead of the silicon gates he had to work with ~27 years ago, he can likely get ahead of the race conditions and address other logic that was needed for better bus arbitration.
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