A4000TX ATX Amiga motherboard

jcanodk

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VC190 trimmer capacitor is for tuning the RTC. For adjusting the VC190 you would need to have an oscilloscope or a frequency counter.
The aim is to make the Y176 crystal oscillate at 32768Hz frequency.

I tune the timmer capacitor as follows:
1. Keep the motherboard powered off when trimming the VC190.
2. Place a CR2032 battery to the battery holder.
3. Connect the oscilloscope probe to U178 pin 17 and ground the probe to GND on the motherboard (for example by connecting it to U178 pin 9 or motherboard's mounting hole).
4. Check what the oscilloscope says for the frequency.
5. If it's something else than 32768Hz, turn the VC190 clockwise or counter-clockwise till you get 32768Hz. After that the tuning is complete.
Brilliant 👏 Short and exact. Just what I needed. You should put this part in the doc with the other assembly instructions.
 

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Arioch1973

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I am definitely interested in one board :)
I just finished building an A2000 Eatx, and kind of itching for more.
 
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Hannibal

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I am now trying to program the PIC16F84A for the PS/2 mouse support. I did the following:

- Installed Windows XP to an old PC and installed the drivers. The PIC K150 programmer is recognized as "Prolific USB-to-Serial Comm Port (COM4)" device in the device manager (cp. attached image).
- Connected the PIC K150 programmer to the A4000TX mainboard; pin 1 VPP to pin 1 on the A4000TX mainboard, etc... (cp. attached image).
- Started "MicroBrn", selected correct programmer K150, COM port 4, loaded HEX file. MicroBrn says "K150 board connected".
- Then clicking on "Program" and setting the fuse settings as described by Hese (WDT, PWRTE, Oscillator and Code Protected); but then getting the following error:



... when selecting "Coninue anyway" I get an error and the chip is not written...

Trying to program this beast for 4 hours now... Any help highly appreciated! Thank you.

PS.: The PIC 16F84A should be genuine, I bought it from mouser.com.

It's been a while but I found this message because I was running into the exact same problem. Here is what I did to fix it:

- Install the software in a VMPlayer VM running Windows XP. I tried running on Windows 11 and I tried a Windows 7 VM and neither worked. Windows 7 would let me write the ROM but then the connection to the K150 would break down before writing the fuses.

- Per default, when selecting the 16F84A in the microbrn chip selector, you will select ZIF socket style programming. You need to switch to ICSP programming or talking through the cable won't work. There is a menu entry in the "Options" menu of microbrn called "ICSP Mode". Select that option and you will see the picture of the chip in the socket on the right change to a picture of the cable pinout.

This way I was able to program the 16F84A in system.
 

turtlesedge

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Can the U206 and U976 chips be programmed with a TL866CS? Is there any reason why they must be programmed with onboard connectors?
 

hese

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It's not needed to use the onboard connectors if you don't want.
You can use any programming device you wish to program those chips if the device supports them.
 

Hirsch

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I got hands on a fully assembled A4000TX. It works so far, but my PS/2 keyboard (Cherry RS 6000 M, PS/2 only) does not work with J200=PC. An Amiga keyboard with J200=AMIGA works fine. Maybe the A4000TX is a little bit picky with some keyboards. Before investigating the board deeper I'd like to ask you whether you can tell me PC keyboard models that are known working or *NOT* working with the A4000TX.

Reading through the thread I found this information:
  • Microsoft keyboards seem to work (post #316).
  • IBM keyboards seem to work while Siemens and Toshiba are problematic (post #429).



Update:
I verified that the A4000TX is working with other PC keyboards now. I'd like to share the information with you which ones are working.

PS/2 PC keyboardworks with A4000TXreported by
Acer KB-2971yesgseb
Cherry RS 6000 WnoHirsch
DEC RT2158TWUKyesSanguineBrah
IBM SK-8820yesHirsch
Microsoft Basic Keyboard 1.0AyesHirsch
SunRace JME-8231noHirsch
 
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cv643d

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I have a zz9000 graphics board in my A4000TX and it has been working great, highly recommend! I recently added a zz9000ax sound card to the setup but I get this horrible sounding background noise from the sound card from the moment I power on the A4000TX. Tripple checked all connections, removed cable for Paula input etc - a loud background buzz is constantly on, also when playing mods/MP3s.

Just wonder if anyone else is running a zz9000ax with their zz9000 in their A4000TX and can confirm if it works for them or not.
 

SanguineBrah

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I got hands on a fully assembled A4000TX. It works so far, but my PS/2 keyboard (Cherry RS 6000 M, PS/2 only) does not work with J200=PC. An Amiga keyboard with J200=AMIGA works fine. Maybe the A4000TX is a little bit picky with some keyboards. Before investigating the board deeper I'd like to ask you whether you can tell me PC keyboard models that are known working or *NOT* working with the A4000TX.

Reading through the thread I found this information:
  • Microsoft keyboards seem to work (post #316).
  • IBM keyboards seem to work while Siemens and Toshiba are problematic (post #429).



Update:
I verified that the A4000TX is working with other PC keyboards now. I'd like to share the information with you which ones are working.

PS/2 PC keyboardworks with A4000TXreported by
Cherry RS 6000 WnoHirsch
IBM SK-8820yesHirsch
Microsoft Basic Keyboard 1.0AyesHirsch
SunRace JME-8231noHirsch
I have a DEC branded keyboard (branded generic keyboard) that works: DEC P/N PCXLA-KE, generic model no RT2158TWUK.

One thing I have noticed with some of my keyboard and mouse issues is that because the 3D printed I/O shield is thicker than a normal metal shield and the tolerances of the cutouts are quite tight, some PS2 connectors don't go in all the way and can make a bad connection, which causes the mouse/keyboard to freak out sometimes.
 

qz3fwd

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I am pretty sure there is no announced date for a V2. If you want one, best to get one. These sort of projects can become OOS. Not like millions of boards are being built. Low volume projects. You gotta jump on them while still available.
 

SanguineBrah

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After extended use and testing, I have noticed consistent issues with the PS/2 mouse support on my board. I've tested 6 different mice, some old, some newer, some ball, some optical, and all of them work for a while then eventually lock up leaving the cursor only controllable via the keyboard shortcuts. Perhaps it is because of my decision to use an external oscillator for U976. I recall the component in the Mouser cart for Y976 was the wrong package so I had to source one elsewhere. I wonder, is everyone using the internal oscillator in their build?

Edit: I reworked my board to use the internal oscillator and this problem seems to be fixed.
 
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turtlesedge

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After extended use and testing, I have noticed consistent issues with the PS/2 mouse support on my board. I've tested 6 different mice, some old, some newer, some ball, some optical, and all of them work for a while then eventually lock up leaving the cursor only controllable via the keyboard shortcuts. Perhaps it is because of my decision to use an external oscillator for U976. I recall the component in the Mouser cart for Y976 was the wrong package so I had to source one elsewhere. I wonder, is everyone using the internal oscillator in their build?
Which crystal oscillator did you use? Can you give us the part number.
 

turtlesedge

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On the BOM there are Qty 7 of ATF16V8B-10JU and Qty 1 of ATF16V8C-5JX.

I'm happy that the ATF16V8B-10JU are for both the 4 x GAL16V8-10 and 3 x GAL16V8-15, but I cannot work out what the ATF16V8C-5JX is for.

Any ideas?

Thanks
What was the ATF16V8C-5JX used for?
 
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