Atari 800 XL Remake

[_The Doctor__]

LED's would just blink with port selections of memory... setting them on purpose might affect some memory upgrades... perhaps a latching circuit would help is it only looked at shadow registers or direct registers... whichever is more commonly used for the purpose...

[+kheller2]

48 minutes ago, reifsnyderb said:

A 1200XL sounds interesting.  I am not sure how memory banking would be done as Atari used a couple bits of PortB for the LED's.  Memory banking like the 800 wouldn't work as the XL's used that space for something else.  (Going off of memory I think it was the international character set.)  So, that is a question I have.  But, once I get the board dimensions, it's possible.

I would not build it to 1200XL OS specs, but the standard 800XL OS.   You can always mess up banking by pressing the function keys -- even today as I recall with the 800XL OS in a 1200XL.

 

[reifsnyderb]

4 minutes ago, kheller2 said:

I would not build it to 1200XL OS specs, but the standard 800XL OS.   You can always mess up banking by pressing the function keys -- even today as I recall with the 800XL OS in a 1200XL.

 

Good point.  I was thinking about using the 800XL schematic....if I were to get the specs on the board.  I'd hate to lose the LEDs, though, just because I like things to work.

[+kheller2]

29 minutes ago, reifsnyderb said:

Good point.  I was thinking about using the 800XL schematic....if I were to get the specs on the board.  I'd hate to lose the LEDs, though, just because I like things to work.

You would need to make some changes anyway, as the keyboard 4050s are not on the mainboard.

 

[+tf_hh]

On 11/11/2021 at 9:09 PM, reifsnyderb said:

1.  To confirm....Do you mean to have left and right audio (L Audio Analog Mixed and R Audio Analog Mixed, above)  ran up to the space between what is normally the RF connector (and possibly DVI) and the monitor jack with a ground on the header as well?

 

Sorry for late reply, wasn´t online some days. Yes, correct.

 

On 11/11/2021 at 9:09 PM, reifsnyderb said:

2.  Why is a PS/2 keyboard connector needed when the Atari already has a keyboard?

 

Because several people have defect keyboards and the prices for new keyboards or spare parts raised a lot the last 1-2 years. It´s simply cheaper to add an external PS/2 keyboard, for most games the internal keyboard isn´t really needed ?

 

On 11/11/2021 at 9:09 PM, reifsnyderb said:

It looks like I should add Pin 11 of the SIO socket to the Simple Stereo/PokeyMAX header as well.

 

This would be very cool!

 

[+tf_hh]

On 11/12/2021 at 1:13 AM, reifsnyderb said:

I printed it out and will take a look at it.  If I were to connect all of the lines I could always change their use with the CPLDs.  I'll take a closer look after I finish the current additions.

 

PLEASE - Don´t use these old crap DRAMs expansions any more! For years these ones have always been the biggest source of trouble. Every real experienced Atari hardware guy will commit this. Countless hours have been spend to make such spaghetti monsters work fine. And, together with modern CPLD and/or FPGA based, external expansions there are new problems.

 

It´s a great point of evolution that today all memory expansions uses SRAM. So my 2 cents:

 

- Include the standard 512 KB expansion in your logic

- Include the possibitily to add an U1MB board

 

Switching between these options is possible using a few jumpers. You have more than enough free space on the new PCB ?

 

[reifsnyderb]

1 hour ago, tf_hh said:

 

PLEASE - Don´t use these old crap DRAMs expansions any more! For years these ones have always been the biggest source of trouble. Every real experienced Atari hardware guy will commit this. Countless hours have been spend to make such spaghetti monsters work fine. And, together with modern CPLD and/or FPGA based, external expansions there are new problems.

 

It´s a great point of evolution that today all memory expansions uses SRAM. So my 2 cents:

 

- Include the standard 512 KB expansion in your logic

- Include the possibitily to add an U1MB board

 

Switching between these options is possible using a few jumpers. You have more than enough free space on the new PCB ?

 

I am only using SRAM and increased it to 1MB.  All PortB pins are now ran to the CPLD that controls the memory so it would be possible to re-program that CPLD to use the PortB pins however you like.  As the MMU is also a CPLD, changes can be made there, as well.  Both CPLD's use JTAG.  Jumpers are on-board for the memory CPLD and a jumper for the MMU so it can be set for the U1MB board.

[+kheller2]

If you can make all this fit into a 600XL (with video jack for us NTSC folks) then the board can be reworked for just about any other XL case.  The only reason I teasingly mentioned that 1200XL is because of Flashjazzcat's blog on converting a 1200 into a 1400ish (PBI, XL OS, 5V DC supply, then all the expansions).  I dream for someone to mold plastic to make a 1200XL / XEGS  keyboard design.

[reifsnyderb]

Boards are finished but aren't scheduled for delivery until December 1st.  It takes so long to prototype stuff due to shipping times alone....   ?

[BillC]

21 hours ago, reifsnyderb said:

Good point.  I was thinking about using the 800XL schematic....if I were to get the specs on the board.  I'd hate to lose the LEDs, though, just because I like things to work.

Jumpers could be added to allow changing the function of the LEDs to suit owners preference.

[BillC]

I was looking at the images and don't see any color adjustment potentiometer on either PCB!

[reifsnyderb]

On 11/23/2021 at 6:30 PM, BillC said:

I was looking at the images and don't see any color adjustment potentiometer on either PCB!

There is a potentiometer to the left of the GTIA chip.  It's R38 with three pads.  KiCad doesn't have the model to render the potentiometer so it just leaves the pads.

[reifsnyderb]

Today, I took a break from KiCad and was working on my Atari 800.  For the first time ever I got it working direction with S-Video with one of those cables from 8bitclassics.com.  (I learned the hard way that I shouldn't have composite video and S-Video plugged in at the same time.)  I now have the 800 connected to a fairly large flat screen TV and PacMan is huge.  Anyhow, I got to thinking about what would be involved in making an Atari 800 board as well and decided to compile what I believe to be a complete hardware map of the Atari 8-Bit computer.  I used Mapping The Atari and various other sources on the internet.  Axlon and XE memory banking information is included.  I've attached it here if anyone is interested.  I'll do some more research on other memory banking schemes and add them in the future.

Atari Hardware Map.pdf

 

Edit To Add:  The binary addresses in the attached map really help to understand how the MMU and banking work.

Edited November 25, 2021 by reifsnyderb

[BillC]

1 hour ago, reifsnyderb said:

There is a potentiometer to the left of the GTIA chip.  It's R38 with three pads.  KiCad doesn't have the model to render the potentiometer so it just leaves the pads.

I don't know it you are aware of it but Atari designed the XL/XE models with this potentiometer accessible from the bottom, to simplify adjustments without having to disassemble the case.

 

On your new 800XL board the potentiometer appears to be in the same location as the original PCB, but there is no hole to allow adjustment from underneath.

Location is important in order to line up with holes in the bottom case and RF shield and the type of potentiometer is also important if retaining this feature is desired.

[reifsnyderb]

8 minutes ago, BillC said:

I don't know it you are aware of it but Atari designed the XL/XE models with this potentiometer accessible from the bottom, to simplify adjustments without having to disassemble the case.

 

On your new 800XL board the potentiometer appears to be in the same location as the original PCB, but there is no hole to allow adjustment from underneath.

Location is important in order to line up with holes in the bottom case and RF shield and the type of potentiometer is also important if retaining this feature is desired.

I just checked both the 800 XL board and 600 XL boards and it may be possible to put that potentiometer back in the original location.  It will probably have to be through-hole tech, though.  On the new (unreleased) XL board it's off by around 13mm or so.  I'll take a look at it.  

[reifsnyderb]

I was looking into re-adding the through-hole potentiometer.  One of the goals with this board is to use as many parts as possible that are commonly available in 2021.  So I've been looking mainly at parts that are available via DigiKey and Mouser.  The ACP CA9-V10 potentiometer appears to be available but their distributor (Vimix Intl.)  doesn't show it in stock.  I've been trying to avoid used parts where possible and collecting parts off of ebay is something to try to avoid.  So, the compromise here is to add the capability for this potentiometer.  If you have one, want to pull it off a board, get it from your parts bin, buy it off of ebay, etc., you can do that and solder it in place.  There are two jumpers (JP1100 & JP1101) that would be pulled to disable the current on-board potentiometer.

 

In my search I only found one other through-hole potentiometer of the right value....but it didn't have the same hex hole.

 

My experience with this adjustment is that I never needed it.  I setup the 800XL and it worked fine....as long as I had the RF converter and all the RF stuff.  The colors were fine.  My dad bought it new somewhere around 1985 or 1986.

 

So, here's what I came up with for the 600XL.  I can do the same with the 800XL, of course.

[_The Doctor__]

you would not have to put a hole throught the pcb if you mounted a pot on the bottom side of the board where the hole in the case and shielding is... you can route the board to connect to the correct sides of the pot...

[reifsnyderb]

21 minutes ago, _The Doctor__ said:

you would not have to put a hole throught the pcb if you mounted a pot on the bottom side of the board where the hole in the case and shielding is... you can route the board to connect to the correct sides of the pot...

It's possible and I know it's been done a lot.  However, when I've tried soldering double-sided SMD PCB's it usually resulted in the parts on the opposite side falling off.   ?

 

[BillC]

5 hours ago, reifsnyderb said:

In my search I only found one other through-hole potentiometer of the right value....but it didn't have the same hex hole.

I found this potentiometer at Digikey that looks like it could work, it is adjustable with a phillips screwdriver top and bottom:

https://www.digikey.com/en/products/detail/te-connectivity-passive-product/409HA504M/2363149

 

And another that appears to have a hex center hole accessible from both sides:

https://www.digikey.com/en/products/detail/amphenol-piher-sensing-systems/PT10MV10-504A1010-S/9555913

 

EDIT: The first one linked is out of stock, but can be ordered. There are over 5,000 of the second in stock

 

 

Edited November 26, 2021 by BillC

[kenames99]

On 11/21/2021 at 9:09 PM, reifsnyderb said:

I could probably put buffering into the 800 XLM but there isn't space for the 600 XLM.  

 

I am thinking a 74LS245 would work as a buffer?  Would there be a difference between DMA and 1090xl?  It would be preferable to do both.   ?

yes there is a difference , hmmm, just had a thought. gimme a bit of time to work thru it. in the meantime, the schematics for the 1400xl should show you the 1090xl way.

 

Ken

 

[reifsnyderb]

20 hours ago, BillC said:

I found this potentiometer at Digikey that looks like it could work, it is adjustable with a phillips screwdriver top and bottom:

https://www.digikey.com/en/products/detail/te-connectivity-passive-product/409HA504M/2363149

 

And another that appears to have a hex center hole accessible from both sides:

https://www.digikey.com/en/products/detail/amphenol-piher-sensing-systems/PT10MV10-504A1010-S/9555913

 

EDIT: The first one linked is out of stock, but can be ordered. There are over 5,000 of the second in stock

 

 

Thanks!  I added the potentiometer.

 

[reifsnyderb]

Here's the Beta 2 version of the board as planned.  A few extra features have been added.  In addition to everything discussed, this board adds the capability for a RTC, SIO2SD "hard disk", and XEP80-II emulation by using a Teensy 4.1 microcontroller.  Since the chip for SIO2PC isn't available, at the moment, there is also a USB breakout so the Teensy should be able to handle that as well.  I just have a "little" programming to do to make it happen.   ?

 

Beta 1 will be in this week and I will start assembling it ASAP.  Hopefully, other than the one problem I found, and fixed on Beta 2, it should be fine.

 

Once Beta 1 is confirmed, I'll make any needed changes and get Beta 2 ordered.  Hopefully, Beta 2 will be the first 800XLM board.   ?

[ivop]

Perhaps you could move the two jumpers that block installing a larger WaveBlaster board. This port is continuously called an S2 DreamBlaster port, but it's just a generic WaveBlaster port, invented by Creative, and introduced to the Atari 8-bit MIDI world by me, except it is missing -12V and +12V and audio-in mixing. But there are a lot of boards, other than the S2, that could be connected. Even SerdaShop has different options. S2, X2, C1, and the new E-Wave. Older boards from the 90's are too big, but also work through a flat cable.

 

Edited November 28, 2021 by ivop

[ClausB]

On 11/23/2021 at 7:37 AM, tf_hh said:

PLEASE - Don´t use these old crap DRAMs expansions any more! For years these ones have always been the biggest source of trouble. Every real experienced Atari hardware guy will commit this. Countless hours have been spend to make such spaghetti monsters work fine. And, together with modern CPLD and/or FPGA based, external expansions there are new problems.

 

I agree that SRAM is better for modern incarnations of Atari hardware. But DRAM expansions are not "crap." It's all we had back in the day when SRAM was small and expensive.

 

I have 40 years of "real" hardware experience and I won't "commit this."

[reifsnyderb]

46 minutes ago, ivop said:

Perhaps you could move the two jumpers that block installing a larger WaveBlaster board. This port is continuously called an S2 DreamBlaster port, but it's just a generic WaveBlaster port, invented by Creative, and introduced to the Atari 8-bit MIDI world by me, except it is missing -12V and +12V and audio-in mixing. But there are a lot of boards, other than the S2, that could be connected. Even SerdaShop has different options. S2, X2, C1, and the new E-Wave. Older boards from the 90's are too big, but also work through a flat cable.

 

Which 2 jumpers are you referring to?   940 & 941?

 

Edit to add:  An option may be to use shorter jumpers, too.

Edited November 28, 2021 by reifsnyderb