A4000TX ATX Amiga motherboard

The only difference between 424800 and 41S4800 ist that the S Type support CAS before RAS Refresh, like most DRAM Chips. If the RAM Controller dont supported this mode it is simply not used.

ALICE, like AGNUS is an old Design and only Support RAS Only Refresh, because DRAM of that time only support this mode, so both Chips can be used

Fastmem is different since Ramsey is more modern and use CAS before RAS Refresh since this mode is much more flexible and easier to implement.
 
A4000TX rev 1.1 rtc battery type

A4000TX rev 1.1 rtc battery type

A4000TX rev 1.1 BOM mentions BT176 rtc battery should be of type "CR2032H". I can mostly find plain "CR2032" available in shops and online. Some googling for differences says H model is higher capacity, but also it's rechargeable (at least based on some sources).

So the question is:
- Is it OK to use normal plain "CR2032" 3V Lithium rtc battery ? Or is it required to be of type "CR2032H" ?
- Does A4000TX rev 1.1 recharge the rtc battery?

My A4000TX is set to Lithium configuration (D181 installed, R179 not installed, Coin Cell Battery Holder installed). I decided to ask and verify because some Amiga/retro shops sell Lithium Coin Battery adapters for Amiga, with normal plain CR2032, and have "appropriate electronic components to avoid the battery charges from the computer".
 
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Does anyone have a solution for ATX case backplate for A4000TX rev 1.1 ?
Yes, I have a 3D drawing for the A4000TX I/O shield. See the attachment.

A big thank you to Alf24de (@A1k.org forum) for creating and sharing the 3D drawing.

- - - Updated - - -

A4000TX rev 1.1 BOM mentions BT176 rtc battery should be of type "CR2032H". I can mostly find plain "CR2032" available in shops and online.
You can ignore the H suffix, it just means that the CR2032 battery (holder) to be installed should be a horizontal one.

The motherboard can either be soldered so that it recharges or doesn't recharge the battery. I have soldered your motherboard so that it does not recharge the battery so you can use normal CR2032 batteries that are easily available everywhere.
 

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@Hese: on the subject of the IO Shield - any good idea where to get this 3d printed, or even better getting an actual cut metal plate ?

Edit: duh - just figured out you just select metal on one of them 3d print sites :roll:
 
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Does anyone have a solution for ATX case backplate for A4000TX rev 1.1 ?
Yes, I have a 3D drawing for the A4000TX I/O shield. See the attachment. A big thank you to Alf24de (@A1k.org forum) for creating and sharing the 3D drawing. - - - Updated - - -
A4000TX rev 1.1 BOM mentions BT176 rtc battery should be of type "CR2032H". I can mostly find plain "CR2032" available in shops and online.
You can ignore the H suffix, it just means that the CR2032 battery (holder) to be installed should be a horizontal one. The motherboard can either be soldered so that it recharges or doesn't recharge the battery. I have soldered your motherboard so that it does not recharge the battery so you can use normal CR2032 batteries that are easily available everywhere.
Cool, thanks a lot hese!
 
My freshly Build A4000TX almost worked straight away, only 2 issues:
- RTC Chips seems to be China made relabled M6242B since only Oscillator work but nothing else, the original RP5C01 from my old A4000D work in the Soket...
- My PS/2 Keyboard stop working at a CTRL-A-A reset and put Garbage to the Amiga unless Powercycle, Amiga Keyboard and my external PS/2 Adapter (W95Key from Aminet) work flawless...
- PS/2 Mouse does not work at all

Are the Source and the Circuit diagram for the PS/2 Keyboard and Mouse controller available?
I can vaguely remeber that my external PS/2 Adapter behave similary until i heavily patched some Bugs and Timing issues 20 Years ago...
 
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My freshly Build A4000TX almost worked straight away, only 2 issues: - My PS/2 Keyboard stop working at a CTRL-A-A reset and put Garbage to the Amiga unless Powercycle, Amiga Keyboard and my external PS/2 Adapter (W95Key from Aminet) work flawless... - PS/2 Mouse does not work at all
I don't know if it helps at all, but PS/2 Mouse seems to work on my A4000TX rev 1.1 (built by hese). I set the kbd/mouse jumpers to PC position, and both the PC PS/2 keyboard and PC PS/2 mouse works OK. Then again i've only had the A4000TX for a couple of days now, so not much use yet, but I haven't encountered any issues so far..
 
I solved the PS/2 Mouse issue, seem a little bad luck with the Chips, the PIC16F84A lost three bits betwen programming/verify and first power on :(
I reprogrammed it an all worked as expected, to be on the safe side i replaced it. Fortunately, there were still a couple left from my my PS/2 keyboard adapter experiments in 2000.
 
I found two small things in rev 1.1 that could be improved in the next version:
- Power the RP5C01 RTC Chip from the ATX Standby power instead of the +5V main supply. This Old Chip and required filtering components draw much more Current than modern RTC. I measured ~28µA so a CR2032 discharged relatively quickly (~1 year) while Amiga is powered off. With this change the ATX Powersupply can power the RTC while plugged in and switched on like in every PC so the Battery is nor discharged
- move the SIMM Slots some >=3 mm away from the Zorro Slots. If some Zorro Card use all the allowed area (e.g. Picasso IV with Pablo Module) it collide with big PS/2 SIMM (32/36 Chip Modules) in U851 Socket.
 
Hi, great to hear your suggestions for further upgrades but hopefully the next upgrade on this board from Hese will be PCI. This will open up a whole new world of expansion for our beloved ageing Amigas.
 
I have a couple of VP101-3BA video DACS here for my builds and was wondering if I still need to populate the LM385 (D507) & 1K (R466) resistor?
 
Should work out of the Box if D507 and R466 are unpopulated, but to get correct Video Levels R509 must changed from 562Ohm to 542Ohm...
Without this change the video levels are a bit off since internal reference of VP101-3BA is 1,2V while LM385-1.2 is 1,23V.
 
@dorken,

Thanks for the info. May as well use the LM385-1.2 as I have a few of them but no 542Ohm resistors.
 
I'm thinking this would make a great project to while away the pending winter. However, I'm not clear on the kit required to assemble and set up.
Would I need anything more than a soldering iron and lots of patience? Do any of the chips (GAL, PIC) require programming? Other than the kickstart ROMs, that is.
Thanks
 
Well, you need the patience, thats for sure :)

(Disclaimer: I'm no expert in this, what is below is my own experience as a hobbyist and I have no formal electronics education)

I ordered the exact number of components as a set from mouser and went through a bag of components at a time, checking them off the list.

PIC and ATMega needs programming, but all of that is in the instructions that Hese provides, and those programmers are fairly cheap too.


Also a good magnifying lamp too (led, diopter 3 or better), as lots of the resistors and caps are reduced to 805 size on this board (in contrast to the 1:1 remakes).


Make sure you get an iron with direct heating element (maybe the KSGER T12, which is a Hakko knockoff) and use a knife tip (KU worked for me), as it will be good to drag solder components in place.


Get some good sticky flux (I used Amtec NC-559-V2-TF, because it can handle a lot of heat), and some Kester 4mm 60/40 leaded solder. Consider using two sizes - one for SMD, and one for TH, as the smaller soldering wire will need meters to supply the Zorro connectors... :)


I Used around ~30 hours building two TX's side by side, but I wanted components to be straight and soldering to be solid (I had only previously done a ReAmiga 1200 v1.5, but the TXs really taxed my patience..).


Thats my two cents :)
 
Many thanks for the detailed response, screemo. Great stuff (y)(y)

Based on the information you provided, I have the confidence to give it a go and have pm'd hese.

How difficult is it to source the non-BOM components? The Amiga chipset looks simple enough, but from this and other threads it looks like some have struggled to source stuff like the CPU connector and DAC.

Thanks again.
 
Many thanks for the detailed response, screemo. Great stuff (y)(y)

Based on the information you provided, I have the confidence to give it a go and have pm'd hese.

How difficult is it to source the non-BOM components? The Amiga chipset looks simple enough, but from this and other threads it looks like some have struggled to source stuff like the CPU connector and DAC.

Thanks again.

Hey ChewChew,

I used the Mouser BOM that Hese provided as part of the order, and sourced most of the custom chips from screemo's thread https://www.amibay.com/showthread.php?112041-A1200-and-A4000d-chipsets&highlight=1200+chipset
With regards to re CPU card connector - I'm just sticking to the onboard '030, but if i've understood you and you google the part number KEL 8807-200-170s-f, you should see a US supplier as the first returned item that will sell it to you for under £30 shipped.

Then there is a handful of parts that are easily sourced online. It is an expensive hobby :)
 
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With regards to re CPU card connector - I'm just sticking to the onboard '030, but if i've understood you and you google the part number KEL 8807-200-170s-f, you should see a US supplier as the first returned item that will sell it to you for under £30 shipped.

Thanks, ObjectiveD. I too intend to use the onboard 030, but would to keep open the option of fitting a CPU card in the future. Also, I don't like to leave a project incomplete :)

Then there is a handful of parts that are easily sourced online. It is an expensive hobby :)

Hmm, you've got me worried. How much did the stuff from Mouser cost?
 
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