Thinking of getting a new Atari 800XL board made....

[+kheller2]

10 hours ago, reifsnyderb said:

Well, the PBI has the /halt line and the modern remake of the 1090XL (and 1091XL) supports the /halt line.  So, a 1090 board can be made.   🙂

 

Yes, but I was implying of doing the 128 onboard the 800XL.  

[Overange]

1 hour ago, kheller2 said:

Yes, but I was implying of doing the 128 onboard the 800XL.  

The easy option instead of trying to wedge in the 130XE extra memory circuit,  would be to install or upgrade with one of the many memory expansions out there.

 

Please correct me if I am wrong but I think this is one of the reasons why the 65XE Remake was not made with 130XE Memory, but they went with adding the 512K Rambo on board as an option. I built one and its great, but I decided to install U1MB, so the 512K Rambo part is unused and redundant.

[+Stephen]

Another vote for just using the U1MB.  It provides so much more than just extra RAM.

[reifsnyderb]

6 minutes ago, Stephen said:

Another vote for just using the U1MB.  It provides so much more than just extra RAM.

Have no memory at all?

[reifsnyderb]

I suppose an option would be to make the board as simple and cheap as possible.  Then people could either use it as-is or upgrade it any way they want......

[Overange]

31 minutes ago, reifsnyderb said:

I suppose an option would be to make the board as simple and cheap as possible.  Then people could either use it as-is or upgrade it any way they want......

Like making it modular, however you run the risk of how to you ensure all 3rd party add ons will work, and like was mentioned before, are you taking responsibility for those add ons?

Unless you make the simple board open source with disclaimers?

[reifsnyderb]

2 minutes ago, Overange said:

Like making it modular, however you run the risk of how to you ensure all 3rd party add ons will work, and like was mentioned before, are you taking responsibility for those add ons?

Unless you make the simple board open source with disclaimers?

Well, the boards already are modular in a way.  DRAMs can be removed and SRAM can be installed, for example.  I was just thinking about stripping it down to a fully functional 64k 800XL but with an SRAM replacing the DRAMs, a single ROM chip for the OS and BASIC, etc., etc.  Minimal components.  Then if somebody wants to upgrade it they can install the whatever module...like they do with a OEM board.  The parts count could be reduced to maybe a 3rd or even a 1/4 of the components of a normal 800XL board and still be fully functional.

[Overange]

Just now, reifsnyderb said:

Well, the boards already are modular in a way.  DRAMs can be removed and SRAM can be installed, for example.  I was just thinking about stripping it down to a fully functional 64k 800XL but with an SRAM replacing the DRAMs, a single ROM chip for the OS and BASIC, etc., etc.  Minimal components.  Then if somebody wants to upgrade it they can install the whatever module...like they do with a OEM board.  The parts count could be reduced to maybe a 3rd or even a 1/4 of the components of a normal 800XL board and still be fully functional.

Exactly, but with out those parts on board you reduce the risk of EM noise etc etc and with the reduced component count or maybe use SM parts, it could then be possible to make one board to fit in either a 600XL or 800XL?

Will need to double check that thou...

[reifsnyderb]

2 minutes ago, Overange said:

Exactly, but with out those parts on board you reduce the risk of EM noise etc etc and with the reduced component count or maybe use SM parts, it could then be possible to make one board to fit in either a 600XL or 800XL?

Will need to double check that thou...

SRAM is said to be quieter.  With a reduced component count, there would be a lot less soldering, too.

 

The 600XL and 800XL boards have different connector locations, unfortunately.  A couple examples are:  1.  The joystick ports are located at different distances from the upper right corner.  2.  The PBI edge connector distance from the upper right corner is different. 

[bfollowell]

Whatever you do, please try to limit SMDs, preferably to none. Even though I'm just 57, my old eyes, hands, and fingers just can't do it anymore. I can solder through-hole all day long without issue, but I just can't do SMD work.

 

[reifsnyderb]

12 minutes ago, bfollowell said:

Whatever you do, please try to limit SMDs, preferably to none. Even though I'm just 57, my old eyes, hands, and fingers just can't do it anymore. I can solder through-hole all day long without issue, but I just can't do SMD work.

 

I am contemplating the following, but all in through-hole components:

 

Keep all the improvements already made to the original board posted.

Replace all of the DRAM circuitry (everything from DRAMs to delay line) with an SRAM chip.  (64k of AS6C1008)

Replace the OS and BASIC ROMs with a single chip.  (SST39SF010)

Combine the function of the 74LS138 and remaining required memory control into a single ATF16V8 PLC chip.

Eliminate the ferrite beads.

Simplify the power supply circuit.

Replace many resistors with resistor arrays and networks.

Replace the audio circuit with the one @mytek has used.  (Component reduction and sounds better.)

Replace the video circuit with the A800 video circuit.  (Component reduction and improved handling of composite video.)

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

Use the simplified clock circuit with the 74LS14 chip.  (Component reduction.)

 

 

 

[+mytek]

2 hours ago, reifsnyderb said:

2 hours ago, Stephen said:

Another vote for just using the U1MB.  It provides so much more than just extra RAM.

Have no memory at all?

U1MB only provides extended RAM. The 64K base RAM still needs to be supplied by the main board.

 

I used a UM61512AK-15 which are in a skinny 0.3" 32-PDIP package taking up minimal board space, but are still THT. Although you could use the wide 0.6" 32-PDIP packaged AS6C1008 as you mentioned, but there is no cost savings, and it does require more board space as well. Yes I know the UM61512AK-15 is a no longer manufactured part, but there has never been an issue with getting them, and UTsource.net is a reliable source.

 

These nest real easily inside the CPU or Antic footprint.

 

EDIT: for those that don't want the U1MB, they could always plug-in one of your PBI memory expansion boards to have more than 64K.

 

EDIT2: these can be pre-tested with the TL866II Plus Programmer before installation into the board if no socket is to be used - nice for nesting  since no additional socket is required for stacking.

[Overange]

1 hour ago, mytek said:

I used a UM61512AK-15 which are in a skinny 0.3" 32-PDIP package taking up minimal board space, but are still THT. Although you could use the wide 0.6" 32-PDIP packaged AS6C1008 as you mentioned, but there is no cost savings, and it does require more board space as well. Yes I know the UM61512AK-15 is a no longer manufactured part, but there has never been an issue with getting them, and UTsource.net is a reliable source.

 

These nest real easily inside the CPU or Antic footprint.

 

Great idea but the trouble is if the SRAM goes faulty, it would have to be de-soldered  

 

With the AS6C1008, I have already built a prototype that plugs into the antic and it works great  

 

 

 

[Mathy]

Hello guys

 

4 hours ago, bfollowell said:

Whatever you do, please try to limit SMDs, preferably to none.

 

IIRC PCB's can be ordered with SMDs preinstalled.

 

Sincerely

 

Mathy

 

[bfollowell]

30 minutes ago, Mathy said:

Hello guys

 

 

IIRC PCB's can be ordered with SMDs preinstalled.

 

Sincerely

 

Mathy

 

 

Well, if the cost isn't prohibitive, that would certainly simplify things for me.

 

[reifsnyderb]

31 minutes ago, Mathy said:

Hello guys

 

 

IIRC PCB's can be ordered with SMDs preinstalled.

 

Sincerely

 

Mathy

 

They can be, sure.  But, in small quantities, the cost can dramatically increase.

[+mytek]

4 hours ago, Overange said:

Great idea but the trouble is if the SRAM goes faulty, it would have to be de-soldered  

Never stopped Atari from doing the same, or for that matter nearly every piece of electronic gear built today. But none the less the UM61512AK-15 can still be nested and socketed, only requiring another 40-pin ML IC socket stacked to add the necessary clearance height for the CPU or Antic. EDIT: Many of the 576NUC+ and 1088 series builders did that very thing, for as you mentioned if it ever went faulty.

 

4 hours ago, Overange said:

With the AS6C1008, I have already built a prototype that plugs into the antic and it works great  

Yet another board is required taking that approach. That's good for existing systems, but why take that approach with a new design when the pad footprint can simply be incorporated.

[+mytek]

2 hours ago, Mathy said:

IIRC PCB's can be ordered with SMDs preinstalled.

I have no direct experience doing this, but I doubt that is very cheap if only doing a board or two at a time for a DIY builder. I would think it would have to be done in fairly large quantity to make it worthwhile. So this likely means someone independently buying and reselling. Not exactly DIY friendly, but it has been done this way in semi-kit form by at least one vendor I know of, thus making it more feasible for a DIY builder to still assemble a board themselves.

 

EDIT: I see that I reiterated partially what was already stated by @reifsnyderb in a previous post.

[Overange]

26 minutes ago, mytek said:

 

 

Yet another board is required taking that approach. That's good for existing systems, but why take that approach with a new design when the pad footprint can simply be incorporated.

 I wanted to prove this IC and the control circuit would work. Prior to incorporating it into the final design.

[reifsnyderb]

Some progress has been made with this semi-modern 800XL board and I've used @mytek 's design in the audio section.  It's on it's own ground plane, too.  I decided to put the 4 100k resistors in 1 package so the total component count is about 50% of the original.  I re-used component numbers from the original but they don't equate to the original specs.

 

 

[+bf2k+]

19 hours ago, bfollowell said:

Whatever you do, please try to limit SMDs, preferably to none. Even though I'm just 57, my old eyes, hands, and fingers just can't do it anymore. I can solder through-hole all day long without issue, but I just can't do SMD work.

 

Ditto!

[Jfcatari]

I am also up for a nice TH designed 800XL board!

[Overange]

8 hours ago, reifsnyderb said:

Some progress has been made with this semi-modern 800XL board and I've used @mytek 's design in the audio section.  It's on it's own ground plane, too.  I decided to put the 4 100k resistors in 1 package so the total component count is about 50% of the original.  I re-used component numbers from the original but they don't equate to the original specs.

 

 

Nice little Single Transistor Audio Mixer design  

 

It may be worth you prototyping this, just to ensure you have the right values etc. and its not a lot of parts so should be easy to bread board it.

 

@mytek had to implement a mod to  the TK_II_Stereo board to stop Squelching/Distortion of the output by using a 390 Ohm resistor across 5 and 6 on his RN1/RN2 resistor networks or in your design across 7 and 8 of the RN5 resistor network.

 

I had to do this mod here in the UK, as such games like Yoomp! was distorting like hell on the bass notes.

 

Edited October 26, 2023 by Overange
typo

[reifsnyderb]

1 hour ago, Overange said:

Nice little Single Transistor Audio Mixer design  

 

It may be worth you prototyping this, just to ensure you have the right values etc. and its not a lot of parts so should be easy to bread board it.

 

@mytek had to implement a mod to  the TK_II_Stereo board to stop Squelching/Distortion of the output by using a 390 Ohm resistor across 5 and 6 on his RN1/RN2 resistor networks or in your design across 7 and 8 of the RN5 resistor network.

 

I had to do this mod here in the UK, as such games like Yoomp! was distorting like hell on the bass notes.

 

I think R5, in the circuit I posted, will handle this. 

 

I've tested this out on a full 600XL board.  It sounds a little different than the original design but it sounded pretty good.  Unfortunately, that board has been somewhat dismantled and the parts re-used elsewhere.

 

 

 

 

[Overange]

48 minutes ago, reifsnyderb said:

I think R5, in the circuit I posted, will handle this. 

 

I've tested this out on a full 600XL board.  It sounds a little different than the original design but it sounded pretty good.  Unfortunately, that board has been somewhat dismantled and the parts re-used elsewhere.

 

 

 

 

For our older ears 🤪 , its like when the kids moan about CRT TVs making the.... as my kids call it - 'The Cat Scarer Sound', I say, 'Well we had to live with it in our day and just ignored it, like you do when we say do your chores' 🤣

 

Well done, its coming along nicely 👍