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2023 Advanced PCB Remake For the 800XL -- Revision 1.1


reifsnyderb

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Since the other two threads, below, discussed both an evolution to this board and some testing with it's predecessor, I figured I'd start a new thread for the final result.  Once I complete the document with the schematics, notes, and assembly instructions, I'll post it in this thread as well.

 

For reference, this board evolved from the board originally contemplated here:  https://forums.atariage.com/topic/355940-thinking-of-getting-a-new-atari-800xl-board-made/

This thread was created to discuss the conversion of Revision 1.0 to run the W65C02 processor:  https://forums.atariage.com/topic/356723-w65c02-on-r1-of-the-advanced-pcb-remake-for-the-atari-800xl-yes-it-works/

 

Tonight, I ran yet another test to ensure that another possibility existed prior to posting.

 

To re-cap what changes and improvements have been made, here is the introduction in the draft document I am creating on this board:

 

---------------------------------

Introduction:

 

Like many projects, this board has considerably evolved. The original intent was to take the Atari 800XL system board (C061851 Revision D) and add some upgrades. The original upgrades were as follows:

 

1. Chroma video output on monitor port pin 5.

2. +5VDC on PBI pins 47 and 48.

3. /HALT on PBI pin 33.

4. The optional blur capacitor (C56, 180pF) was re-added.

5. An enhanced MMU with the following changes:

  a. Open collector PBI Refresh to prevent ANTIC’s Refresh signal from being shorted out due to the actions of some PBI upgrades.

  b. PBI RAM at $D600-$D7FF. (Inspired by Atari’s original XL Sweet 16 design document.)

  c. ROM access on read only.

6. Improved DB-9 joystick ports.

7. Full copper ground planes on both sides.

8. Isolated audio and isolated video ground planes.

 

After some discussion, on the Atari Age forums, many additional changes were made. These include:

 

1. Reduced the component count by making the following changes:

  a. Replaced all DRAM circuits with SRAM circuits.

  b. Replaced the OS and BASIC ROMs with a single chip.

  c. Combine the functions of the 74LS138 and memory control into a single PLC.

  d. Eliminate the ferrite beads and unnecessary 1nF capacitors.

  e. Simplify the power circuitry.

  f. Replace many resistors with resistor arrays and networks.

  g. Replace the audio circuit with the audio circuit designed by mytek on the AtariAge forums.

  h. Remove the RF video in favor of composite and S-Video.

  i. Use the simplified clock circuit used by mytek on the AtariAge forums.

2. Multiple memory options that include 64k only, 128k XE, and 320k RAMBO.

3. Addition of the jumpers as per Atari’s original XL Sweet 16 design document. (These are optional.)

4. Addition of three breadboard regions for user customization.

5. Channel select switch has been re-purposed as a ROM bank select switch to permit two possible OS/BASIC configurations.

6. Addition of separate pads for console keys.

7. Most components have values and/or part numbers on the board to aid in assembly and troubleshooting.

8. Addition of two locations for a fuse and a zener diode to protect against power supplies going over- voltage. (This is experimental.)

----------------------------------------------

 

This week, I finished assembly and proved that the board can be programmed to run as a 130XE.  The memory alone can be easily programmed to use anywhere from 16k to 128k exactly like a 130XE by using an AS6C1008.  If an AS6C4008 is installed, the memory can be configured to run in 320k RAMBO mode.  I realized that some people would probably complain that 320k wasn't enough.  So, one of the features of this board is the enhanced MMU that I like to think of as a "baby Carmen" after the "Carmen" chip used in the 1400XL.  This MMU uses an ATF22V10 and processes the R/W signal and sets up the PBI refresh to act as an open collector line.  When properly programmed, shorting the Refresh line to ground (to disable the MMU) won't bother me anymore and the ROMs are only active during a read cycle.  So, where does this all lead?  4MB of Axlon RAM running on an XL!   🙂  So, why bother with 1,088k when you can just skip over it!   :-D

 

As a test, I reprogrammed my prototype Mega 4 XL board to bank 4MB of RAM at $CFFF.  This test was a success and I was running a 4MB 800XL this evening.   :-D

 

It's also nice to have a 130XE type machine in an XL case.  There's a nicer keyboard, PBI, cartridge slot at a decent location, plenty of memory, and I can easily add other options like the 80 column card.  🙂

 

Another test I ran was to ensure that the 130XE video blitz demo works.  It does!   🙂

 

Finally, here's some pictures:

 

First, the installed board:

(Note the parallel port is in use.  A 1091XL is connected.   🙂  )

 

Installed.thumb.jpg.02f9e6c97f9baaca928f31432fb631eb.jpg

 

Here's a rendering of the board as well:

(Almost all component values are labelled and I even labelled most of the pins on the main Atari LSI chips.)

 

Board.thumb.jpg.7983ec5ed9c56b655dbd17173a6bd443.jpg

 

 

This is the prototype 1090XL Mega 4 XL board I re-programmed for the 4MB of Axlon RAM:

 

Mega4XL.thumb.jpg.9b435a4ad27af1f9ea4e2b18bbcc961a.jpg

 

 

Here's SpartaDOS-X happily running with 4MB of RAM:

 

Sparta.thumb.jpg.6b9c7908e3ee9865178adbceb0d260cf.jpg

 

 

Here's SimCheck showing 4MB of Axlon RAM:

 

Axlon.thumb.jpg.86d126f400bd2ded9fbe8cb386d54284.jpg

 

Here's SimCheck showing 128k of RAM while running as a 130XE:

 

XEConfig.thumb.jpg.8a3f63b31bbab50b92d438c3fdd4043d.jpg

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Edited by reifsnyderb
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@reifsnyderb,

 

Congrats!  Well done!

 

1. Since I assume that this board can always be the base for various popular extensions (especially those produced by Lotharek), it would be possible in subsequent revisions to provide access to popular signals using goldpin points. I am referring to signals: CI, EXTSEL, IRQ, MDP, and the address line. This will allow the use of various popular extensions on this board, and their installation will be much simpler. Since you have so much space on the board, you can place a port compatible with the VBXE adapter over ANTIC, which will allow this card to be installed without an additional adapter.

 


2. Do you happen to have links to articles: "Replace the audio circuit with the audio circuit designed by mytek on the AtariAge forums"?

 

3.

> "8. Addition of two locations for a fuse and a zener diode to protect against power supplies going over- voltage. (This is experimental.)"

 

There should probably be more of these areas. The possibility of re-wiring can come from the main power supply, but also from the cartridge port, PBI, SIO, and joystick. See the topic A8PicoCart. It's possible that discussions about protection against parallel connection of the cart to a PC could also apply to this board, and solutions could also be transferred to it. Then there won't be a problem whether someone switched the switch in Fujinet incorrectly or connected the A8PicoCart to Atari and PC at the same time (not possible in the latest project).

 

4.  Thank you for not occupying the space of the RF modulator, where my future video boards can fit.

 

 

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Great to see it come together :)

 

I am awaiting for my 1st Version of my own 800XL redesign PCBs to arrive, should of been yesterday ( Friday ) but FedEx choose not to deliver it till Monday GRRR.....

I will update my OP with more details soon, But what I can say is my Video Output on the Prototype Board I Built looks amazing, in both Composite and S-Video :) so hopefully it will perform the same when on board. 

 

@Piotr D. Kaczorowski

 

image.thumb.png.7244d57bca3b3d5f595e0852888fe8a9.png

This is the basic Audio Circuit that is being used.

 

The unmarked line is from Pin 37 of the POKEY

AUD on the Right is Audio Out  ( obviously ) ;)

 

You will find this on @mytek web page, in its different variations, for each system.

 

https://ataribits.weebly.com/systems.html

 

 

Hope this helps?

 

 

 

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54 minutes ago, Rybags said:

Nice, but a question.

Couldn't the overall board size have been significantly reduced and still been retained by the default screw positions given the amount of component reduction?

Though that said, would there be a cost saving to make it worth the effort?

I appreciate your viewpoint. Preserving the positions of legacy components, such as the Atari ICs and connectors, not only defines the board dimensions but also guarantees compatibility with modern third-party upgrades.
This also implies that additional onboard features can be incorporated into the open spaces.

 

Unlike certain ZX Spectrum 48K remakes, which are almost half the size of the original board, the lower section of those boards lacks components that would affect its size.

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4 hours ago, Piotr D. Kaczorowski said:

1. Since I assume that this board can always be the base for various popular extensions (especially those produced by Lotharek), it would be possible in subsequent revisions to provide access to popular signals using goldpin points. I am referring to signals: CI, EXTSEL, IRQ, MDP, and the address line. This will allow the use of various popular extensions on this board, and their installation will be much simpler. Since you have so much space on the board, you can place a port compatible with the VBXE adapter over ANTIC, which will allow this card to be installed without an additional adapter.

 

I didn't add pickup points for these signals as there are other signal points to be added for other extensions then there are even more points to be added for even more extensions.....and it goes on and on.  The other issue is that since this is a 2 layer board, routing all of the signal points to neatly laid out areas would have taken days as a lot of other lines would have had to be moved.

 

So, with the breadboard areas, it's possible to add whatever signal points you would like to add.  Also, by labeling many of the LSI chips, it's easier to find whatever signal points you want to use. 

 

 

 

 

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2 hours ago, Rybags said:

Nice, but a question.

Couldn't the overall board size have been significantly reduced and still been retained by the default screw positions given the amount of component reduction?

Though that said, would there be a cost saving to make it worth the effort?

I didn't reduce the board size for the following reasons:

1.  It would take many days to reduce the board size.

2.  The board is held level in the case by the front edges of the board.

3.  The biggest cost reduction was not going to a 4 layer board.

4.  Reducing the board size would have eliminated the breadboard positions.

5.  There won't be enough of these boards made to have a decent quantity of scale type savings.

 

Best Regards,

 

Brian

 

 

 

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4 minutes ago, reifsnyderb said:

I didn't add pickup points for these signals as there are other signal points to be added for other extensions then there are even more points to be added for even more extensions.....and it goes on and on.  The other issue is that since this is a 2 layer board, routing all of the signal points to neatly laid out areas would have taken days as a lot of other lines would have had to be moved.

 

So, with the breadboard areas, it's possible to add whatever signal points you would like to add.  Also, by labeling many of the LSI chips, it's easier to find whatever signal points you want to use. 

 

 

 

 

Adding extra functions this late in is very hard and can lead to creating other issues.

 

As the age-old adage suggests, it's crucial to draw a line in the sand.

 

If anyone else wants to design and build their own variant, I would say try it, its great fun and you can learn a lot from it, but be warned it can be expensive ;) 

 

The 800XL Gerbers are out there in the domain, to give you the start to ensure board dimensions are correct.

 

 

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10 hours ago, reifsnyderb said:

 

This week, I finished assembly and proved that the board can be programmed to run as a 130XE.  The memory alone can be easily programmed to use anywhere from 16k to 128k exactly like a 130XE by using an AS6C1008.  If an AS6C4008 is installed, the memory can be configured to run in 320k RAMBO mode.  I realized that some people would probably complain that 320k wasn't enough.  So, one of the features of this board is the enhanced MMU that I like to think of as a "baby Carmen" after the "Carmen" chip used in the 1400XL.  This MMU uses an ATF22V10 and processes the R/W signal and sets up the PBI refresh to act as an open collector line.  When properly programmed, shorting the Refresh line to ground (to disable the MMU) won't bother me anymore and the ROMs are only active during a read cycle.  So, where does this all lead?  4MB of Axlon RAM running on an XL!   🙂  So, why bother with 1,088k when you can just skip over it!   :-D

 

As a test, I reprogrammed my prototype Mega 4 XL board to bank 4MB of RAM at $CFFF.  This test was a success and I was running a 4MB 800XL this evening.   :-D

 

It's also nice to have a 130XE type machine in an XL case.  There's a nicer keyboard, PBI, cartridge slot at a decent location, plenty of memory, and I can easily add other options like the 80 column card.  🙂

 

Another test I ran was to ensure that the 130XE video blitz demo works.  It does!   🙂

 

 

Wait, What, indeed!?!?   A 130XE in a 800XL case.  The only thing that might be sweeter, for a really old guy like me, might be a 130XE in an original 800 case. However, there are likely reasons why it cannot work.   But ...

futurama-fry.gif

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Hi @reifsnyderb,

 

Firstly, thank you for your hard work! Looks like I have another build project to look forward to! 😁

 

I have a question since I am not an electronics expert. In your redesign, a lot of pickup pads for certain signals from the original PCB have been removed in favor of breadboard area. I was thinking if I was to get a manufacture a board, I may opt to go with the vias untented to recover some solder points on the board. Do you (or anyone else) have thoughts on this? 

 

For those who do not know what I am talking about, here is a screen shot of the options I am talking about. The one I am thinking about is "Untented"

 

IMG_0887.thumb.jpeg.51c473c76ea43800f666f5d2f74212c4.jpeg

 

 

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21 minutes ago, scorpio_ny said:

Hi @reifsnyderb,

 

Firstly, thank you for your hard work! Looks like I have another build project to look forward to! 😁

 

I have a question since I am not an electronics expert. In your redesign, a lot of pickup pads for certain signals from the original PCB have been removed in favor of breadboard area. I was thinking if I was to get a manufacture a board, I may opt to go with the vias untented to recover some solder points on the board. Do you (or anyone else) have thoughts on this? 

 

For those who do not know what I am talking about, here is a screen shot of the options I am talking about. The one I am thinking about is "Untented"

 

IMG_0887.thumb.jpeg.51c473c76ea43800f666f5d2f74212c4.jpeg

 

 

My thoughts are that having the vias "untented" would make them easier to solder to.  With this through-hole board, SMD pads are a non-issue.  I doubt that, electronically, there would be any difference.  That being said, with "tented" vias it's still easy to remove the solder mask with a razor blade or exacto knife.

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3 hours ago, kenp said:

Wait, What, indeed!?!?   A 130XE in a 800XL case.  The only thing that might be sweeter, for a really old guy like me, might be a 130XE in an original 800 case. However, there are likely reasons why it cannot work.   But ...

I am planning on selling at least my other 4 boards with programmed PLC chips as soon as I get the build document finished.  If enough people are interested, I'll get more boards made.  So, for those that are interested, please let me know.

 

I am sure a 130XE board could be made for an 800 case.  The 3rd and 4th joystick ports wouldn't work, however.  I am not sure what solution would be found in regards to the RAM/OS slots.  I could imagine a few different options.  The slots could be kept the same and the /S0 through /S7 select line system used.  Optionally, the slots could be turned into 1090 like slots for upgrades.  It would be a lot of work and I don't know how many people would be interested in this.

Edited by reifsnyderb
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You can have i/o ports 3/4 work alongside banking, I'd suggest a quick conversation with candle about his method, which was employed for the incognito board. even though it's virtual hardware to actual ports in his implementation, it's still translates to real hardware if you would like.

Edited by _The Doctor__
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Ok.  I've been thinking about pricing.  I am going to go with $48 per board plus $20 for domestic shipping.  (I don't know what international shipping would be at this time.)  I'll program the PLC's, test them, and solder the sockets in place for $10 per PLC.  Two PLC's are minimum if you want a 64k system.  All 3 PLC's are necessary if you want to have another memory configuration.  I'll release the source code for all of the PLC's with the build document, when I finish it within the next few days. 

 

Right now, the following memory configurations have been tested:

16k  (I doubt anyone wants this.   lol   )

64k  (No PLC is necessary, just solder in 4 wire jumpers where marked)

128k  RAMBO

128k 130XE (w/ ANTIC banking)

 

320k hasn't been tested because I forgot to order an AS6C4008 chip.  (Oops.)  I think the PLC program I came up with will work.  Once I order more chips, I'll verify it.

 

Other configurations could be programmed, of course, but I doubt anyone would be that interested.  i.e.  32k, 48k, and probably 8k (by modifying the MMU).  lol

 

Oh, yeah, I am not going to be responsible for bad soldering.  (I already have a note about that in my draft config document.)

 

Please PM me if you would like one.  If there is enough of a response, I'll need to order more boards.  Right now, I have 4 extra boards.

 

 

 

Edited by reifsnyderb
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20 hours ago, reifsnyderb said:

I am planning on selling at least my other 4 boards with programmed PLC chips as soon as I get the build document finished.  If enough people are interested, I'll get more boards made.  So, for those that are interested, please let me know.

 

I am sure a 130XE board could be made for an 800 case.  The 3rd and 4th joystick ports wouldn't work, however.  I am not sure what solution would be found in regards to the RAM/OS slots.  I could imagine a few different options.  The slots could be kept the same and the /S0 through /S7 select line system used.  Optionally, the slots could be turned into 1090 like slots for upgrades.  It would be a lot of work and I don't know how many people would be interested in this.

Not many but the really old school type, like me.  The cards? yes, what could the memory cards slots be used for?  I'll look up that 1090 project but one thing comes to mind, either an SD or SSD card.  Mega delusions of grandeur thinking of an Atari 800 with a 4TB SSD card in it.  🙂  (actually with any version of an SSD in it.  so much room in that case.)

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49 minutes ago, kenp said:

Not many but the really old school type, like me.  The cards? yes, what could the memory cards slots be used for?  I'll look up that 1090 project but one thing comes to mind, either an SD or SSD card.  Mega delusions of grandeur thinking of an Atari 800 with a 4TB SSD card in it.  🙂  (actually with any version of an SSD in it.  so much room in that case.)

This could be done with a 1090 type card as well.   🙂

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