1088XEL Alternative Mother-Board Project

[flashjazzcat]

So it looks like S0 is used by something on Rapidus? What for?

 

Enabling/disabling the core, which is pretty much essential if you want to get the 6502 back. But the whole point of the plugin approach to the BIOS is that you can assign whatever functions to whichever signals depending on the upgrades in the machine. So Rapidus could as easily live on M1 if (IIRC) Covox wasn't present.

 

In any case, it looks like we need a 1088XEL plugin which formalises and names the assignments in the menus.

[thorfdbg]

One thing I think I showed by using Xuel's test program is that correct PMG data is displayed when stuffing GRAFCTL directly, but when using DMA, there are errors. I believe this would then also point to ANTIC being the culprit?

Not necessarily, but it means that the ANTIC-GTIA pair is out of sync. IOWs, either Antic puts the PMG data on the bus at the wrong cycle (for whatever reason), or GTIA samples the bus at the wrong spot (for whatever reason). That GTIA displays the PMGs correctly once the data is in its internal GRAFxx registers has been seen indeed. Just that it's the wrong data that goes there to begin with.

 

So one way or another, the two chips are slightly out of sync.GTIA samples too early, or ANTIC puts the signal on the bus too late. Some sort of timing/wiring problem.

[+Stephen]

Not necessarily, but it means that the ANTIC-GTIA pair is out of sync. IOWs, either Antic puts the PMG data on the bus at the wrong cycle (for whatever reason), or GTIA samples the bus at the wrong spot (for whatever reason). That GTIA displays the PMGs correctly once the data is in its internal GRAFxx registers has been seen indeed. Just that it's the wrong data that goes there to begin with.

 

So one way or another, the two chips are slightly out of sync.GTIA samples too early, or ANTIC puts the signal on the bus too late. Some sort of timing/wiring problem.

OK - I can try a different ANTIC. I won't use the original GTIA from the 800XE I sourced the parts from because it is defective. I bought an ANTIC/GTIA pair and had them running in the 800XE before pulling the chips for the 1088XEL.

[Dropcheck]

Maybe I missed it. Forgive me if I did.

 

But are you using the PAL versions of ANTIC and GTIA chips? Or the NTSC versions? Just changing the clock isn't enough.

[+mytek]

Maybe I missed it. Forgive me if I did.

 

But are you using the PAL versions of ANTIC and GTIA chips? Or the NTSC versions? Just changing the clock isn't enough.

 

Opps !!!

 

Just kidding Yes Stephen has been using both the PAL Antic and PAL GTIA as well as switching the primary clock crystal to 3.546894 Mhz.

 

- Michael

[Dropcheck]

Good.

 

My mind sometimes takes a vacation on me at the most inopportune moment, and I was hoping I was the only one that that happened to. I need to be special in something.

Edited June 27, 2017 by Dropcheck

[+mytek]

Good.

 

My mind sometimes takes a vacation on me at the most inopportune moment, and I was hoping I was the only one that that happened to. I need to be special in something.

 

My mind takes a vacation every day, so don't feel bad... it's nice to be special

 

- Michael

[Matej]

Yogi is working on YMari2XEL project... Internal OPL3 (18ch,stereo FM soundcard). More infos here:

http://atariage.com/forums/topic/267000-ymari-opl3-cartridge-by-tori-yogi/?p=3794127

[sl0re]

No ROMs, MMU, or Freddie. this is all handled by the U1MB. So yes to the top five chips in your list (2 Pokeys if you want Stereo).

 

And most of the other chips have their part numbers printed on the PCB's silkscreen. Speaking of which, on the final rev boards I will be eliminating the Atari specific part numbers on the silkscreen, since especially where it concerns Antic and GTIA those are variable depending upon PAL or NTSC, or even when manufactured.

 

- Michael

 

Do versions matter? Re: would a CPU or support chips from a 400/800 or 1200xl work?

[+DrVenkman]

 

Do versions matter? Re: would a CPU or support chips from a 400/800 or 1200xl work?

 

Michael will need to answer for sure, but I'd think that a 6502 from a 400/800 would not work; pretty sure the XEL is like the XL/XE machines in that they use the modified 6502C "Sally" version customized with the addition of a HALT signal pin.

[+mytek]

 

Do versions matter? Re: would a CPU or support chips from a 400/800 or 1200xl work?

 

As DrVenkman pointed out, the CPU needs to be the same one as used in the XL/XE line which I believe first appeared in the later 400/800 series. This would be the one that had the built-in Tri-State registers controlled by the HALT signal pin of the Antic chip so that it could take over the bus. In the first 400/800 machines they were using the stock un-modified 6502 same as an Apple II, and made this work by having separate Transceiver chips to give Antic control. By going to the new chip, Atari was able to eliminate several other 'glue' logic chips in the process.

 

As for the other VSLI chips (Antic, GTIA, Pokey, PIA), any version of such that was used over the years will work --- assuming you use PAL and NTSC specific versions depending upon the video standard you need. And although there were different versions of Antic made to accommodate different DRAM memory refresh timing's, since the XEL uses SRAM either version will work. So this means a big cost savings if the one from the 400/800 is used instead of the later XL/XE version (BEST Electronics: 400/800 PAL Antic $10 vs $30 for XL/XE version).

 

- Michael

[+DrVenkman]

And although there were different versions of Antic made to accommodate different DRAM memory refresh timing's ...

 

Michael, can you go into any detail on this? I know there are two versions (NTSC parts C012296 and C021697) - I ask because I'm still struggling with my difficult 1200XL and trying to determine which was the "stock" original. One of my machines came to me with one the earlier version, the other machine came with the later version. I have no idea if they were modded, changed or worked on before I got them.

[seastalker]

RE: alternative cases. Would this fit in any vintage floppy drive case be it Atari, Commodore or Apple?

[Van]

 

Michael, can you go into any detail on this? I know there are two versions (NTSC parts C012296 and C021697) - I ask because I'm still struggling with my difficult 1200XL and trying to determine which was the "stock" original. One of my machines came to me with one the earlier version, the other machine came with the later version. I have no idea if they were modded, changed or worked on before I got them.

The CO12296 is the older version that shipped in early model A800s. Not sure when the CO21687 was introduced but even early 800XLs can be found with the CO12296. As I understand, the older version could only refresh 64K of DRAM, but the newer could generate refresh for up to 128K. Beyond that the two seem identical, I have the CO12296 in the XEL with no side effects that I can see, this chip was pulled from an 800XL.

Yogi

[Van]

RE: alternative cases. Would this fit in any vintage floppy drive case be it Atari, Commodore or Apple?

The 1088XEL is designed to the Mini-ITX standard of 170mm x 170mm so it would be dependent on the case It might fit an 810 case but I don't have one handy to measure ATM.

Yogi

[seastalker]

Although it may be heresy, the internal width of a standard Commodore 1541 drive is just over 7.5 inches (length you get almost double that). I don't have Atari floppy drives anymore to measure. Would still prefer ANY retro case over a modern ATX if no one designs one with an atari feel.

[Van]

Although it may be heresy, the internal width of a standard Commodore 1541 drive is just over 7.5 inches (length you get almost double that). I don't have Atari floppy drives anymore to measure. Would still prefer ANY retro case over a modern ATX if no one designs one with an atari feel.

At under 7" x 7" there are a lot of case options. No need to feel like it's 'breaking the rules', this is a DIY project and using the mini-iTX standard just makes it easier for builders that don't want to do a case mod. So by all means feel free to explore different options. I'm working on a rack mount case, the challenge is to give it a "Atari XL' feel

Yogi

[KLund1]

From the last few above, it looks like it might be best to get all your chips from a signal donor machine. I would suggest 600XL's as they are all completely socketed.

I have one ready to donate when these boards are ready for public consumption! fyi

[Van]

From the last few above, it looks like it might be best to get all your chips from a signal donor machine. I would suggest 600XL's as they are all completely socketed.

I have one ready to donate when these boards are ready for public consumption! fyi

Better still if the donor is booting/working, because you will need to know all the VLSI chips work. In addition a working mobo is good for verifying the U1MB and UAV, as the U1MB will need it's headers changed to straight ones unless Lotharek begins to offer this option.

 

So even if you source a chipset from Best or else where, I would suggest having a test system. That's not to say you can't get by without it, just that you need to eliminate doubt. Look for a cosmetic 'dog' , as-is and a model with sockets, early XL 'HongKong' or 600XL (I'll take your word on all of the 600s being socketed). Look for cracked or broken case, bad keyboard, untested; these should be pretty cheap.

 

With a little luck and descent soldering skills, chances are the XEL should boot first try

Yogi

[+David_P]

Best has 600xl motherboards with all chips for $55.

[+Stephen]

I'll offer a service for swapping out right angle headers for the PROPER connectors if nothing comes from asking Lotharek to make the boards the way Candle intended them.

[Van]

Best has 600xl motherboards with all chips for $55.

That's good news Stephen, it will make things much easier for people!

 

At $55, It's more then the chips themselves; ~$40 with one PoKEY buying them a' la carte. I was hasty above, in order to test the U1MB in a test 600XL system it will need to have a 64K upgrade, so a stock 600XL would not work. BUT you could source your chipset from the NOS 600XL mobo with less risk then buying a 'as is' off Ebay. and if Stephen does the U1MB re-work for you, you can consider the U1MB as 'TESTED'

 

Another benefit with a donor mobo: if you are handy desoldering, could source the cart connector and guide plastic (not sure if the

BEST mobo comes with the plastic). The XEL doesn't have the slot cuts for the cart plastic so you don't REALLY need it for a top loading case. The straight pin Cart connector can be sourced from a HK supplier but in lots of 5, so you either have extras or re-sell/share some to other builders. Same supplier has ECI connectors too but in lots of 10 so you'll have a lot of extras..

 

For the UAV, contact Bryan and try to have him replace the screw terminal with the pin header SIP he uses on the 4050 footprint. So order either a 'Plug in' with pin header instead of green term, or 'Kit' with a extra 6 pin header instead of the Green terminal. If you buy a 'Basic', you will need to source the pin-to-pin SIPs and the 2.0mm DIP header and shunts. Not a biggie but it's added parts to find.

 

Yogi

Edited July 4, 2017 by Van

[+mytek]

I'll offer a service for swapping out right angle headers for the PROPER connectors if nothing comes from asking Lotharek to make the boards the way Candle intended them.

 

Very nice of you to offer Stephen. Perhaps to better get Lotharek's attention we should start a poll on whether people in general would have a problem with the U1MB's coming with straight headers instead of the right angle ones it now comes with. According to flashjazzcat if the U1MB is located in the 'proper' spot, it shouldn't matter what style of header is used. So instead of making a special XEL version, it would seem better just to make them all the same if at all possible.

 

 

For the UAV, contact Bryan and try to have him replace the screw terminal with the pin header SIP he uses on the 4050 footprint. So order either a 'Plug in' with pin header instead of green term, or 'Kit' with a extra 6 pin header instead of the Green terminal. If you buy a 'Basic', you will need to source the pin-to-pin SIPs and the 2.0mm DIP header and shunts. Not a biggie but it's added parts to find.

 

I just received an order of UAV's from Bryan that came with the proper XEL ready configuration. So most likely if you tell him that you want the XEL version he'll know what you are talking about.

 

- Michael

[+mytek]

I'll be joining the PAL test team for the 1088XEL this week. Got my PAL Antic , GTIA, and crystal from BEST. And so that I can sync into PAL video, also picked up a small inexpensive PAL/NTSC auto switching LCD monitor as well.

 

Should be very enlightening to see what eye see

 

Also made another addition to the next rev 1088XEL board, adding a video header so that perhaps an internal monitor may be utilized (thinking All-In-One design).

 

Latest simulation of what the board will look like...

 

 

EDIT: Also incorporates other changes such as modified MPBI assignment, and change to summing amp inputs for Left and Right audio inputs.

 

- Michael

Edited July 4, 2017 by mytekcontrols

[Van]

 

I just received an order of UAV's from Bryan that came with the proper XEL ready configuration. So most likely if you tell him that you want the XEL version he'll know what you are talking about.

 

- Michael

I thought you had mentioned that before but wanted to make sure it was clear to all that they should request the UAV headers configured for the XEL. Bryan seems like a good guy to deal with so it's very easy to get the UAV ready to go

 

The latest additions to the V1.1 look good, only problem I see is you're running out of space to add anything else

Yogi