Atari 800 XL Remake

[Sinjinhawke]

I don’t know if I can even ever use these boards but this project intrigues me.  I have a dead 600xl board and I imagine using the good parts with this board.

[reifsnyderb]

I decided to solder an SIO connector in to see if SIO works with my 1050.  ?

 

(You can see the back and side of it on the upper right of the table.)  

 

 

 

 

Edited January 17, 2022 by reifsnyderb

[+David_P]

I admire your discipline.  If I were testing and booted MULE, I wouldn't be able to resume work until I was First Founder (as a human).

[spicyjack]

16 hours ago, David_P said:

I admire your discipline.  If I were testing and booted MULE, I wouldn't be able to resume work until I was First Founder (as a human).

^^^^^^^^^^^  this.... or something other than "Garbage Scow Captain"

[reifsnyderb]

Sound!!  The parts for the sound came in yesterday and were soldered in place.  I discovered I forgot a resistor and soldered it in place.  The 600XLM now has sound!

 

The board schematics are being updated so as to ensure the next board has all the fixes.

 

Still on the agenda:

 

  1.  Connect and test the keyboard.

  2.  Install the Teensy and program it to function as an internal SD drive.

  3.  Program the Teensy as a real-time clock.

  4.  Program the Teensy to act as an SIO2PC device through it's USB port.

  5.  Test the TKII keyboard circuitry.

  6.  Test the memory banking for 192k, 576k, and 1024k banking.

 

Unable to test at this time due to chip shortage:

  1.  Onboard MIDI

  2.  Onboard SIO2PC (independent from the Teensy)

 

Picture of sound circuitry.  Note the added resistor...

 

 

Edited January 22, 2022 by reifsnyderb

[+mytek]

13 hours ago, reifsnyderb said:

Unable to test at this time due to chip shortage:

  1.  Onboard MIDI

Anything I can help you with? I do have a small supply of PICs over here in my stuff, although I thought I sent you a PIC12F1572 a while back - do you need another one?

 

[reifsnyderb]

38 minutes ago, mytek said:

Anything I can help you with? I do have a small supply of PICs over here in my stuff, although I thought I sent you a PIC12F1572 a while back - do you need another one?

 

I just checked and I have 2 of the PICs you sent me for MIDI.  Thank you again.  

 

I was thinking I can't get the H11L1 chip as a normal search at DigiKey or Mouser shows it being either not available or non-stocked..  After seeing your message, I tried checking on Octopart and DigiKey does have 32 H11L1M chips.  Looking at the datasheets they look about identical and I'll order a few H11L1M chips for testing.  However, with only 32 available it looks like that chip may not be available for long.  I didn't think to expand my search away from H11L1 chips to compatible chips thinking compatible chips would show up in the same search.

 

I need to order some parts for another project I am working on really soon and will include the H11L1M chips with that order.

 

Edited January 22, 2022 by reifsnyderb

[+mytek]

2 hours ago, reifsnyderb said:

I need to order some parts for another project I am working on really soon and will include the H11L1M chips with that order.

I checked Digi-Key this morning and they had 300 of the PIC12F1572-I/P chips in stock, but just checked again and now it's "0". Don't know if that was a glitch in the system or someone snatched them up. Been hearing about a lot of scalper's getting in on the action surrounding chip shortages, as well as automobile shortages. Ford and a few others have imposed no sell restrictions on some of their vehicles because of this.

 

So you better grab those opto chips while you still can

 

[reifsnyderb]

Update.

 

I recently found out Teensy 3.5's are out of stock and won't be in until some time around the end of the year.  While I did get the SD Card Arduino code to compile on the built-in Teensy 3.5, there is some debugging needed until an on-board SD card based drive is functional on the board.  Some additional board hacking was done to get the Teensy 3.5 working as it needs to be on prior to the computer being turned on.  (Go figure.)  But, because of the chip shortage, the ATF1504's are also hard to find, too.  So I've been working on some other projects such as the Atari 1090 memory cards.  (I had to convert to Xilinx CPLD's due to the chip shortage and programming problems.)

 

Anyhow, I figured I'd post an update because I'll get the other stuff I am working on working first then get back to the Arduino code on the Teensy 3.5.

 

I can't easily convert to Xilinx CPLD's on the 800XLM and 600XLM boards, however, because they are 3.3 volts and only 5 volt tolerant.  So, this means they will take 5 volt inputs but 3.3 volt outputs.  3.3 volt outputs present some problems as some 5 volt chips are ok with it while others are not.  Adding level shifter chips would take up more board space and create more complexity, of course.

Edited February 27, 2022 by reifsnyderb

[BillC]

On 2/26/2022 at 4:53 PM, reifsnyderb said:

I can't easily convert to Xilinx CPLD's on the 800XLM and 600XLM boards, however, because they are 3.3 volts and only 5 volt tolerant.  So, this means they will take 5 volt inputs but 3.3 volt outputs.  3.3 volt outputs present some problems as some 5 volt chips are ok with it while others are not.  Adding level shifter chips would take up more board space and create more complexity, of course.

Xilinx chips aren't completely 5V tolerant, it was discovered with the U1MB that connecting directly to RD4/RD5 at the MMU socket could damage the chip and that inline resistors are required.

[reifsnyderb]

15 minutes ago, BillC said:

Xilinx chips aren't completely 5V tolerant, it was discovered with the U1MB that connecting directly to RD4/RD5 at the MMU socket could damage the chip and that inline resistors are required.

Does the U1MB use a XC9572XL?  Is that why there are 180 ohm resistors between a U1MB and RD4 and RD5 then?

 

I just ordered some boards for something, yesterday, whereby I am depending on Xilinx's datasheet stating that their CPLD's are 5V tolerant as I have 24 5V inputs into a Xilinux XC9572XL.  ?

There isn't space to put 180 ohm resistors.

This lack of 5VDC electronics is going to be a huge problem.

 

[flashjazzcat]

4 hours ago, reifsnyderb said:

Is that why there are 180 ohm resistors between a U1MB and RD4 and RD5 then?

Yes. The original run of boards lacked the resistors, but Candle advised users to fit them on the motherboard or in the MMU cable after a couple of carts blew the CPLD, which he supposed was 5V tolerant (because datasheet said it was).

Edited March 1, 2022 by flashjazzcat

[reifsnyderb]

2 hours ago, flashjazzcat said:

Yes. The original run of boards lacked the resistors, but Candle advised users to fit them on the motherboard or in the MMU cable after a couple of carts blew the CPLD, which he supposed was 5V tolerant (because datasheet said it was).

Thanks for the quick confirmation.  I've got the board coming and will see if it blows the Xilinx or not.  Knowing that now I'll also work on my backup plan of using 74LS series logic chips.   I'll also look into using level shifters on the inputs....but the board will have to be a lot bigger.  (I suppose a double-sided board is a possibility but the only time I tried one the parts fell off the back side of the board when soldering to the front side....so it didn't work out too well.) 

[+mytek]

31 minutes ago, reifsnyderb said:

Thanks for the quick confirmation.  I've got the board coming and will see if it blows the Xilinx or not.  Knowing that now I'll also work on my backup plan of using 74LS series logic chips.   I'll also look into using level shifters on the inputs....but the board will have to be a lot bigger.  (I suppose a double-sided board is a possibility but the only time I tried one the parts fell off the back side of the board when soldering to the front side....so it didn't work out too well.) 

The 576NUC+ needed to have parts on both sides, but the top was THT, whereas the bottom was SMT. I didn't have any problems, although I stuck to using SOIC parts for the SMT which I was able to hand solder without difficulty. If you stick to the largest SMT components hand soldering works very well.

 

After reading through this topic and then seeing the number of posts you've made all together on AtariAge, it dawned on me that you must have pretty much jumped on this project soon after joining these forums. Were you previously on any other Atari related forum? Reason I ask, is that there is a lot to be learned from what is posted here, such as the 180 ohm resistor mods for the early U1MB boards. But it takes time to accumulate all that knowledge. I didn't attempt my first mother board project until I had already been a member for almost 2 years. And in the time leading up to the beginnings of the 1088XEL, I had upgraded stock Atari computers with the same boards and/or designs I intended to eventually incorporate into the XEL, and learned all that I could about the hardware interfacing of such. Even so, the concept for what would become the XEL-CF3 add-on was born about 2/3 of the way through the XEL mother board design and beta testing. I have Jon @flashjazzcat and @bob1200xl to thank for helping me through that process, and for Jon's fantastic efforts and customizing of the U1MB BIOS to bring it all together.

 

BTW, If this is your first rodeo, consider me majorly impressed

 

[reifsnyderb]

Using THT on one side would quickly solve the problem of SMT falling off.   ?

(But there isn't space in this application.)

I actually jumped on the 800XLM a couple of weeks before joining the forums...but haven't been on any Atari forums before.  I guess the only Atari "claim to fame" I have is roughly 15 or 20 years ago I realized atarimania didn't have the BASIC Enterprise program, dug it off a floppy, and submitted it.    http://www.atarimania.com/game-atari-400-800-xl-xe-enterprise_1855.html

?

 

I got the idea for a modernized Atari after seeing that people are re-making boards for retro computers (i.e.  The Apple I) and figured I'd give it a try.

 

After BillC posted about the Xilinx chip problem I remembered seeing those 180 ohm mystery resistors on RD4/RD5 and wondering why they were there.  It was only then I searched for and found the forum posts about Xilinx not really working with 5VDC.  There is a ton of information here and it's a great resource.

 

 

[Dropcheck]

Any updates? ?

[reifsnyderb]

19 minutes ago, Dropcheck said:

Any updates? ?

Nothing right now.  I paused this project when I found out that Teensy 3.5's won't be available until the fall due to the chip shortage.  Given the issues with CPLD shortages I've been working on projects without using CPLD's. 

 

i.e. 

 

I've also been considering doing the 600XLM & 800XLM boards, for example, with ATF1502's for the CPLD's, removing the Teensy, and a few other changes such as onboard RTC.  It would also be possible to specially bank 16k of SRAM to do a Graphics 8 version of an 80 column display...thereby simplifying that idea.

 

After I get the above Axlon boards completed I plan on getting back to the 1090 memory cards and a few other Atari projects I've been working on.  Unfortunately, I was set back a couple of months due to experimenting with some other memory with Xilinx CPLD's and 3.3vdc level shifters that was giving me problems.  (That it takes about 3 weeks to make up a board, get it shipped, and test it, is another huge delaying factor.)  That was another reason I am using 74 series logic chips at the moment.

 

Once the other Atari projects are working I'll get back to this board.