Need BASIC ROM Chip, Or Compatible EPROM

[777ismyname]

Going through a storage unit I found a 600XL that I thought was long gone. I have evidently removed the BASIC ROM, CPU, and another chip or two. 
 

It isn’t absolutely  essential that it have an inbuilt BASIC, but I do have an extra BASIC cartridge or two that I could pull the ROM from - if it will fit in the motherboard socket? If there is a source or one of you guys could burn an EPROM of a different but Atari BASIC compatible BASIC (U-BASIC, Altirra BASIC, etc. with fast FP math pack) I’d be more than happy to buy that. 
 

@dmsc Would it be possible to put Fast Basic (integer version would be fine) onto an EPROM for this purpose?

 

The goal for this 600XL is to not spend much $$$ on it  I think it will get the Lotharek 64KB upgrade and hopefully some extra RAM above 64KB in the near future. A UAV or similar video upgrade and  an internally mounted SDriveMax/SIO2PCSD/similar device will be about all it gets.

Edited November 27, 2019 by 777ismyname
.

[BillC]

The XL/XE computers have a single 8K ROM for internal BASIC, the ROM from a Rev C BASIC cartridge(brown cartridge/silver label) would work, but not the Rev A BASIC cartridge(brown cartridge/label) which contains 2-4K ROM chips.

 

Some versions of the 600XL PCB do have thru holes for a 28 pin socket, even though a 24 pin socket is installed, and a couple jumpers can be moved to allow it to use a 2764 EPROM.

Edited November 27, 2019 by BillC

[+Nezgar]

Since it sounds like you're interested in a couple different BASIC variants, you don't have to pick just 1.

 

You can put multiple switchable 8K BASIC ROM's on a single EPROM using a 2364 adapter such as this: http://store.go4retro.com/2364-adapter/

 

For example, with a 32KB (27C256) EPROM, you could switch between 4 different BASICs. Personally, I made one with Atari BASIC rev C, Alitrra BASIC 1.55, Atari Assembler/Editor, and Star Raiders. with a 64KB (27C512) EPROM you could have 8, which is too many IMHO , and is harder to find a single switch for...

 

The floating point math routines are contained in the OS ROM, so will not be improved with only a BASIC ROM replacement.

[dmsc]

Hi!

19 hours ago, 777ismyname said:

Going through a storage unit I found a 600XL that I thought was long gone. I have evidently removed the BASIC ROM, CPU, and another chip or two. 
 

It isn’t absolutely  essential that it have an inbuilt BASIC, but I do have an extra BASIC cartridge or two that I could pull the ROM from - if it will fit in the motherboard socket? If there is a source or one of you guys could burn an EPROM of a different but Atari BASIC compatible BASIC (U-BASIC, Altirra BASIC, etc. with fast FP math pack) I’d be more than happy to buy that. 
 

@dmsc Would it be possible to put Fast Basic (integer version would be fine) onto an EPROM for this purpose?

 

Yes, it could be ported, but you will loose the ability to compile to disk - as the ROM version won't be at the same address than the current version.

 

Have Fun!

[Kyle22]

If you have a Rev. C Cart, you can take out the ROMs and stack them for use in the XL socket, IIRC.

 

[777ismyname]

21 hours ago, Nezgar said:

Since it sounds like you're interested in a couple different BASIC variants, you don't have to pick just 1.

 

You can put multiple switchable 8K BASIC ROM's on a single EPROM using a 2364 adapter such as this: http://store.go4retro.com/2364-adapter/

 

For example, with a 32KB (27C256) EPROM, you could switch between 4 different BASICs. Personally, I made one with Atari BASIC rev C, Alitrra BASIC 1.55, Atari Assembler/Editor, and Star Raiders. with a 64KB (27C512) EPROM you could have 8, which is too many IMHO , and is harder to find a single switch for...

 

The floating point math routines are contained in the OS ROM, so will not be improved with only a BASIC ROM replacement.

Holy sh!t, that sounds like a winner  I’d LOVE to sit down and learn more assembly. This isn’t going to be my main machine and the budget for it is next to nothing, but this sounds like what needs to happen! 
********************************
 

 

10 hours ago, dmsc said:

Hi!

 

Yes, it could be ported, but you will loose the ability to compile to disk - as the ROM version won't be at the same address than the current version.

 

Have Fun!

Daniel, I’m not sure how that would work for me. If I could save to disk, I could get by and use the laptop to compile. Then again, with the laptop sitting next to the 600XL, I should just use it to code with. 
********************************
 

 

10 hours ago, Kyle22 said:

If you have a Rev. C Cart, you can take out the ROMs and stack them for use in the XL socket, IIRC.

 

Yes, it is a Rev. C. I just now put a 1200XL back together and tried it out  This poor 1200XL keyboard Mylar looks like it has been through war. 
*******************************
 

On 11/27/2019 at 1:09 AM, BillC said:

The XL/XE computers have a single 8K ROM for internal BASIC, the ROM from a Rev C BASIC cartridge(brown cartridge/silver label) would work, but not the Rev A BASIC cartridge(brown cartridge/label) which contains 2-4K ROM chips.

 

Some versions of the 600XL PCB do have thru holes for a 28 pin socket, even though a 24 pin socket is installed, and a couple jumpers can be moved to allow it to use a 2764 EPROM.

I will try to remember to take some decent photographs of the motherboard when I get back over to mother’s house in a few hours. It escapes me at the moment how it is laid out. I have a 65XE parts machine I need to grab and cannibalize for the CPU and such. Hopefully they work. I have a couple of extra 7800 Pokey carts and an extra parts 7800 I can use for parts. My main goal is $cheap$  

[777ismyname]

Thank you to all that responded and all that have sent private messages! For those in the United States, here’s hoping you have a great Thanksgiving Day! For those outside of the U.S., you are welcome to come eat with my family if you can make it by 12:30 Eastern Standard Time (5:30 P.M. G.M.T., I think?)  

[archeocomp]

Still I am puzzled. Are there any incompatibilities? Is it better to install ATARI BASIC rev C, TURBO BASIC XL or ALTIRRA BASIC? Which one should I choose? I have Rev B currently.

[+kheller2]

If you are going to be programming a lot in Atari BASIC, then you really do want to install C to avoid system lockups.

 

[+Nezgar]

You can have them all with multiple 8K BASIC's using a 2364 adapter. 1, 2, 4, or 8 depending on EPROM size.

 

For example, I made one with: Atari BASIC rev C, Altirra BASIC 1.55, Atari Assembler Editor (not sure which of the 2), and Frogger. 3 of them can be easily selected with a single On-Off-On toggle switch.

 

Lots of games work in place of BASIC too, which you can read about more here:

Here's what the board I've used for this in the past looks like. The through-holes for GND/A13/A14/A15 allow you to select up to 8 8K "Banks" (with max size 27512 type EPROM). If you just use a 2764 type EPROM, you don't need to install the pullup resistors, or a switch for a single 8K 2764 type EPROM.

 

[archeocomp]

Nice but I do not want any additional switches, holes in case. I want to keep my 600XL in original purist shape, only better.

 

I was under impression that it is safe to choose any of the three BASICs. But I will stick to Rev C. then.

I only plan to write very BASIC programs with #FujiNet, to do some simple socket communication, when folks developing #FujiNet are that far.

[_The Doctor__]

the 600XL requires memory, and by design Atari made and external memory upgrade for it. The very least you might consider is that upgrade or the two chip upgrade even Atari considered providing and the community made a version of.

[+Nezgar]

4 hours ago, archeocomp said:

Nice but I do not want any additional switches, holes in case. I want to keep my 600XL in original purist shape, only better.

Then you can just use a common 2764 EPROM programmed with only Atari BASIC Rev C + this adapter, and you're set. No switches needed.

 

PM me if you'd like a programmed EPROM+assembled adapter plug-and-play "kit" if you can't find an original mask ROM. (The likes of B&C and BEST have them but can have minimum order requirements, etc)

[BillC]

4 hours ago, archeocomp said:

Nice but I do not want any additional switches, holes in case. I want to keep my 600XL in original purist shape, only better.

 

I was under impression that it is safe to choose any of the three BASICs. But I will stick to Rev C. then.

I only plan to write very BASIC programs with #FujiNet, to do some simple socket communication, when folks developing #FujiNet are that far.

Check your 600XL BASIC socket, if there are 4 extra pads that can be used to install a 28-pin socket instead of the 24-pin then it can easily be modified to use a 2764 EPROM without an adapter.

[BillC]

1 hour ago, BillC said:

Check your 600XL BASIC socket, if there are 4 extra pads that can be used to install a 28-pin socket instead of the 24-pin then it can easily be modified to use a 2764 EPROM without an adapter.

The picture below is from a 600XL PCB with this feature:

 

[archeocomp]

That is exactly PCB that I have. Thanks for jumpers photo. I have TL866 programmer too. But I have also ordered this https://oshpark.com/shared_projects/MjBJtpCb

Not sure which option I will choose. Thanks to all. Rev C is going in there.

[BillC]

42 minutes ago, archeocomp said:

That is exactly PCB that I have. Thanks for jumpers photo. I have TL866 programmer too. But I have also ordered this https://oshpark.com/shared_projects/MjBJtpCb

Not sure which option I will choose. Thanks to all. Rev C is going in there.

Unless you are using a larger EPROM(27128 or higher) and selecting between multiple ROM images you could save the adapter for another purpose.

 

 

 

[+DrVenkman]

On 4/3/2020 at 10:24 PM, BillC said:

The picture below is from a 600XL PCB with this feature:

 

So now that I've pulled my 600XL out of storage, upgraded it to 64K and removed that awful blurring capacitor, I have it out and set up as a mostly-cartridge compact little gaming system. However, while exploring it I realized it has Rev B BASIC and that just irks me. As it happens, I have a set of 2764 EPROMs coming for another project and should have a couple spares, hopefully. I'd like to write Rev C BASIC to one of them and replace the existing chip.

 

I get that I'll be replacing the existing 24-pin socket but the jumper configuration is a bit confusing to me. With my existing 24-pin mask ROM installed, all five of those vias are empty. Is that normal? I gather to use a 28-pin EPROM I'll need to populate 1-2 and 3-4.  So far so good.

 

So now, what does populating 2-3 & 3-4 denote? Why would one use that configuration? I think I've heard you can swap the positions of the OS and BASIC sockets - is that what that jumper configuration does?

[BillC]

4 hours ago, DrVenkman said:

So now, what does populating 2-3 & 3-4 denote? Why would one use that configuration? I think I've heard you can swap the positions of the OS and BASIC sockets - is that what that jumper configuration does?

These jumpers route 2 signals to the correct pin of the BASIC socket for either 24-pin 2364 ROM or 28-pin 2764 EPROM.

4 hours ago, DrVenkman said:

With my existing 24-pin mask ROM installed, all five of those vias are empty.

I haven't seen one myself but some 600XL PCBs are supposed to come with traces between pads instead of the 2 jumpers, this can be confirmed visually or with a multimeter. These traces would need to be cut, and jumpers installed in the other positions, in order to change from ROM to 2764 EPROM. 

[Kyle22]

Don't forget about the Motorola 68764 / 68766 24 pin EPROM. It is difficult to find and sometimes expensive, but a perfect replacement for a 2364 BASIC chip. On board, or in a cart. It works fine.

 

[+DrVenkman]

On 6/26/2020 at 6:21 PM, BillC said:

I haven't seen one myself but some 600XL PCBs are supposed to come with traces between pads instead of the 2 jumpers, this can be confirmed visually or with a multimeter. These traces would need to be cut, and jumpers installed in the other positions, in order to change from ROM to 2764 EPROM. 

Yep, having now done this little mod, I can confirm. My 600XL has (had ) traces between the vias. Today I removed the 24-pin socket, installed a 28-pin machine pin socket, cut those traces and bridged the other two sets (2-3, 4-5) and replaced the buggy rev B BASIC with the latest version of Altirra BASIC instead. 

 

 

[BillC]

10 minutes ago, DrVenkman said:

Yep, having now done this little mod, I can confirm. My 600XL has (had ) traces between the vias. Today I removed the 24-pin socket, installed a 28-pin machine pin socket, cut those traces and bridged the other two sets (2-3, 4-5) and replaced the buggy rev B BASIC with the latest version of Altirra BASIC instead. 

Happy you were able to get it working, it would have been nice if Atari had done this on all the computers with internal BASIC.

[+DrVenkman]

8 minutes ago, BillC said:

Happy you were able to get it working, it would have been nice if Atari had done this on all the computers with internal BASIC.

Agreed! I am going to do some similar-but-not-identical surgery to one of my 1200XL's tomorrow to install set of rev 11 OS ROMs, but at least there Atari provided installed jumpers I can remove and reconfigure to accommodate the modification. Even better, the machine I'm doing it to has 28-pin sockets so won't have to remove and replace the existing ones.