Converting an 800 into a XL - Phase Two: Extra RAM

[+warerat]

I guess the 800 with an XL OS wouldn't be complete without extended memory. This is an "80K" memory module, with the standard 16K as the main bank, and a single 64K SRAM for the extended bank (got to love hi-density SRAM, makes me want to convert all the 800's RAM to SRAM to get rid of those bi-polar supply power hungry 4116 DRAMs!).

 

Three connections to the joystick port for this one. One for extended bank select, and two for the bank numbers. This more or less makes the 800 look like a 130XE. I got a slight timing problem with the memory to work out, but I can switch between DRAM/SRAM and get different banks. Work in progress... Couldn't you call this a "real" 800XE?

[doctorclu]

I guess the 800 with an XL OS wouldn't be complete without extended memory.  This is an "80K" memory module, with the standard 16K as the main bank, and a single 64K SRAM for the extended bank (got to love hi-density SRAM, makes me want to convert all the 800's RAM to SRAM to get rid of those bi-polar supply power hungry 4116 DRAMs!).

 

Three connections to the joystick port for this one.  One for extended bank select, and two for the bank numbers.  This more or less makes the 800 look like a 130XE.  I got a slight timing problem with the memory to work out, but I can switch between DRAM/SRAM and get different banks.  Work in progress...  Couldn't you call this a "real" 800XE? 

1002725[/snapback]

 

That looks a lot better than the rats nest of wiring you had before.

[Cybernoid]

Awesome! This truely shows the upgrade-ability of the 800. Plug in a new Personality board and BAM!

[Almost Rice]

Awesome!  This truely shows the upgrade-ability of the 800.  Plug in a new Personality board and BAM! 

1003117[/snapback]

 

I thought that was the case and have always wondered why it seemed little was made for it compared to the 800xl.

[+warerat]

Awesome!  This truely shows the upgrade-ability of the 800.  Plug in a new Personality board and BAM! 

1003117[/snapback]

 

I thought that was the case and have always wondered why it seemed little was made for it compared to the 800xl.

1003376[/snapback]

 

Probably because even though the 800 had slots, there was no way to access the FULL bus (easily) like the PBI/ECI on the XL/XE line. It is VERY conceivable for one to have PBI devices on the 800-- it is after all, an Atari 8-bit. You'd need to run a line from the $D1XX select on the personality module (which is unused) to the testing slot. Also would need some logic changes in the MMU to allow the FP ROM to be deselected and a few lines to deal with that. Other than the physical interface (and the OS ROM, which has been solved), all the signals are there are on the back connector.

[Great Hierophant]

I assume that combined with the Phase One modification, this would allow you to enjoy the full 128KB of the Atari 130XE and all the XL/XE ROM features except the built-in BASIC and PBI/ECI bus.

 

The only problem I see is the use of the controller ports for RAM bankswitching. What if you want to use the main benefit of the 800, controller ports 3 and 4? If there was a switch that could switch in either "800 mode", which would allow the controller ports to work at the expense of the extra RAM or "800XE mode", which allows the RAM but not the controller ports, then the mod would be perfect and truly valuable.

[doctorclu]

I've been working with an XL OS board for the 800 that Wareat made for me. Nice piece of work. Plug in the board in the rom board slot, and then you run a wire from the XL OS board to the 1st wire in joystick port three.

 

Took me a bit to find the right cable, but I finally found a broken joystick I didn't mind scrapping. Put the XL OS board in a shell from a 800 16K ram board (I like to protect the unique rom boards while the ram tends to overheat in those shells anyway.

 

I had Dave B (Undead Mechanic)

on the line over here as I working with the board. He gave me some good ideas as I was working on this.

 

Well, have to say, I love having an Atari 800 that can...

 

1) Not play the Gorf cartridge (knew it was a true XL then since Gorf only works on a 400/800)

2) Was able to load Olympics 88 (the upcoming game in the high score club contest, that crashes quite well on a stock 800.

3) Plays Crazy Ball Version II.. this was the game that told me I had the memory wired up correctly. (Since I had established that it did not work on the 800, and did not work with the XL OS BOARD once plugged up) I found a great way to test that the banked memory was working with this game.

 

Image is at..

http://www.mushca.com/f/atari/index.php?idx=C

 

4) May not load Sparta DOS 3.4 yet (gets 45 sectors into loading it) but it does not stop the load three sectors in the load to say it is not a XL/XE.

5) An Atari 800 where you can play Asteriods with the XL OS BOARD hooked up, and joystick port 4 STILL works.

 

Yeh this is amazing. Will be a lot of fun to play with more memory as time goes on. Warerat, thanks for making possible what was once thought not possible

[Almost Rice]

Hmm, I think I should do this now. I have an extra 800 that just came in.

[doctorclu]

Hmm,  I think I should do this now.  I have an extra 800 that just came in.

1011295[/snapback]

 

It really makes it like a whole new machine. The memory of the XL, the great keyboard of the 800. Yeh, it's a lot of fun. And I forgot...

 

6) Not having to hold down option to bypass basic!

[Almost Rice]

6) Not having to hold down option to bypass basic!

1011314[/snapback]

 

 

That alone makes it worth doing. Does it work with a MyIDE cart?

[doctorclu]

Hmm,  I think I should do this now.  I have an extra 800 that just came in.

1011295[/snapback]

 

It really makes it like a whole new machine. The memory of the XL, the great keyboard of the 800. Yeh, it's a lot of fun. And I forgot...

 

6) Not having to hold down option to bypass basic!

1011314[/snapback]

 

Actually when I had DavidB and Docrotcod over for a visit a month or so ago, we took a XE and removed the basic chip. Booted no problem.

 

We tried to insert a rom from another cartridge (To see if we could have it come in a game like the XEGS), but most cartridges are 2 chip not one.

 

But yeh, remove the basic chip from the motherboard, no need to hold down option.

[doctorclu]

Awesome!  This truely shows the upgrade-ability of the 800.  Plug in a new Personality board and BAM!  

1003117[/snapback]

 

I thought that was the case and have always wondered why it seemed little was made for it compared to the 800xl.

1003376[/snapback]

 

I think that in easier times it was too expensive to tinker on the 8-bit stuff since they were the price of computers today.

 

By the time that 8-bit Atari's were cheap, people had already grown used to the idea thatn the Atari 800 was limited, too much would need to be done to make bankable memory possible, and just tinkered with XL's and XE's.

 

Atari 800 XL and 1200's were always popular due to the sockets. The 130 XE was popular for it's size and built in memory from the start, though nothing really socketed.

 

The Atari 800 became the machine you used if you like sleek but huge machines with a nice keyboard and for people that could get by with 48K of memory.

 

However, Atari 800's have had some amazing things. Atari 800's have commonly had 256K that they could use as a ramdisk. And that was the common upgrade, there have been much higher.

Other cards like the 80 column card, Omnimon, hard drive interfaces and other things have come up too.

 

But the one card that I thought was missing was the ability to change out the OS board.