Inside the Atari 130XE
Inside the Atari 130XE
131,072 Bytes of Random Access Memory
As I showed in the unboxing, I recently picked up an Atari 130XE.
For those unaware, the 130XE was announced at the January 1985 CES, the first one after Jack Tramiel took over Atari from Warner in July 1984. The 130XE is a slimmed down 8-bit machine, compatible with the 800XL and those before it, but it had 128K of RAM. It shipped in the first half of 1985.
At first, there wasn’t much you could do with the extra RAM. After all, the 6502 used 16-bit address lines, so it could only work with 64K maximum. And the 800XL already shipped with 64K of RAM, and due to overlap with ROM even the full 64K could not be easily used.
Eventually Atari released DOS 2.5 which allowed the extra RAM to be used as a RAM disk (and provided DOS 2 compatibility for the 1050 disk drive). Then OSS BASIC XE shipped with its ability to use the extra RAM in its BASIC programs. At this point Atari had published how to switch in the banks of RAM so more and more software started to use it.
Essentially there was a 16KB “window” in the 64K address space that could be swapped with the extra RAM in 16KB chunks. By swapping RAM you could simulate having more than 64K available to programs, with some restrictions of course.
I never owned a 130XE back in the day, but I’ve been wanting one for a while and found one on eBay for a reasonable price.
I quickly hooked it up to test and noticed there was a problem: the colors are borked
.So I took it apart to clean it (it was pretty dusty) to see if I might notice a problem. Since so many of you liked seeing the guts of the Atari 800XL, here’s an inside look at the 130XE:
When you compare this to the 800XL, you can see that it is not all that different, although I suspect it was designed to be much less expensive to build. It appears this is the Rev 5 motherboard. That wire from ANTIC is odd.
Notable differences from the 800XL:
RAM: The 130XE has 128K of RAM, so two rows of 64K 1-bit chips.
FREDDIE: This chip is new to the 130XE and is responsible for accessing the extra RAM.
The rest of the chips are the same as the 800XL:
The 6502 CPU running at 1.8Mhz.
ANTIC, one of the most famous Atari chips, was responsible for sending display information to the GTIA.
The GTIA chip or George’s Television Interface Adapter controls how the Atari talks to the TV.
The OS ROMs are next, which are 16K.
The BASIC ROM (8K), which is Rev. C as mentioned above.
The Pot Keyboard IC or POKEY chip handles controllers, IO and sound. That it why you hear those beeping noises when loading files from cassette or disk.
And last is the PIA (Peripheral Interface Adapter), which handles the joystick ports.
After blowing out all the dust and re-assembling things, the color problem unfortunately remained. So far, everything else looks like it is working OK but the colors are just off. You can see this pretty clearly when it is booted into BASIC. What should be a lovely shade of blue is now this aggressive red:
I have a hunch as to what the problem might be, although I’m not exactly sure I’ll be capable of fixing it. I’m doing some more tests and will follow-up with additional information soon. Meanwhile, if any of you have any thoughts, please leave them in the comments.
Update: Reader Rick of 8 Bit and More was able to repair my 130XE for me and now it is working as good as new!
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That’s a technical term.
You can send me the 130XE and I will repair it for you.
Actually, the FREDDIE chip was developed under ATARI, Inc. (when ATARI was still owned by Warner) and released as early as September 1984 in France via the ATARI 800XLF Secam-Rose model. It also found its way in a few ATARI 800XLF PAL batches which were released around the same time in the UK and Germany. The bank switching method was also developed by ATARI Inc. for an unreleased 128Ko ATARI 800XL (a prototype picture can be seen in the Best Electronics catalog). There was very little investment in the XE line by the Tramiel family. Most of the technology associated with the 65XE / 130XE already existed at the time of the takeover. It was just cost reduced even further with the loss of the PBI port in exchange of the ECI port (which needed the cartridge port to equal PBI capabilities). There's a great thread on AA about the 128Ko 800XL board and how it equals to the released 130XE: https://atariage.com/forums/topic/187202-130xl-800xlf128k-aka-the-first-130xe . Also read this one: https://atariage.com/forums/topic/139960-800xl-motherboards-variants-ntsc-pal-secam-for-dummies/?tab=comments#comment-1696101