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Bringing BASIC back: Microsoft’s 6502 BASIC is now Open Source

by Christian Liendo

Looks like Microsoft is opening their 6502 Basic https://opensource.microsoft.com/blog/2025/09/03/microsoft-open-source-hist… Today, we’re opening the vault—for real. For decades, fragments and unofficial copies of Microsoft’s 6502 BASIC have circulated online, mirrored on retrocomputing sites, and preserved in museum archives. Coders have studied the code, rebuilt it, and even run it in modern systems. Today, for the first time, we’re opening the hatch and officially releasing the code under an open-source license. Discover the newly open-sourced Microsoft 6502 BASIC code Microsoft’s first products: From the Altair to the Commodore 64 Microsoft BASIC began in 1975 as the company’s very first product: a BASIC interpreter for the Intel 8080, written by Bill Gates and Paul Allen for the Altair 8800. That codebase was soon adapted to run on other 8-bit CPUs, including the MOS 6502, Motorola 6800, and 6809. You can learn more about this time and hear directly from Bill Gates on the Microsoft Learn Website’s History of Microsoft video series or by visiting Bill Gates’ blog. The 6502 port was completed in 1976 by Bill Gates and Ric Weiland. In 1977, Commodore licensed it for a flat fee of $25,000, a deal that placed Microsoft BASIC at the heart of Commodore’s PET computers and, later, the VIC-20 and Commodore 64. That decision put Microsoft’s BASIC at the heart of Commodore’s machines and helped millions of new programmers learn by typing: 10 PRINT “HELLO” 20 GOTO 10 This is BASIC M6502 8K VER 1.1, the 6502 BASIC lineage that powered an era of home computing and formed the foundation of Commodore BASIC in the PET, VIC-20, and the legendary Commodore 64. This very source tree also contains adaptations for the Apple II (“Applesoft BASIC”), built from the same core BASIC source. The original headers still read, “BASIC M6502 8K VER 1.1 BY MICRO-SOFT”—a time capsule from 1978. The version we are releasing here—labeled “1.1”—contains fixes to the garbage collector identified by Commodore and jointly implemented in 1978 by Commodore engineer John Feagans and Bill Gates, when Feagans traveled to Microsoft’s Bellevue offices. This is the version that shipped as the PET’s “BASIC V2.” It even contains a playful Bill Gates Easter egg, hidden in the labels STORDO and STORD0, which Gates himself confirmed in 2010. The enduring appeal of the MOS 6502 CPU The MOS 6502 was the CPU behind the Apple II, Commodore 8-bit series, Atari 2600, Nintendo Entertainment System, and many more. Its simplicity, efficiency, and influence still inspire educators, hobbyists, and hardware tinkerers today. In 2025, interest is as strong as ever. The retro-computing scene is thriving, with FPGA-based re-creations, emulator projects, and active development communities. The Commodore brand has returned with the announcement of a new FPGA-powered Commodore 64, the first official Commodore hardware in decades. Reconstructing and preserving Microsoft BASIC Over the years, dedicated preservationists have reconstructed build environments and verified that the historical source can still produce byte-exact ROMs. Notably, Michael Steil documented and rebuilt the original BASIC process for multiple targets. He has ported the code to assemblers like cc65, making it possible to build and run on modern systems. This open-source release builds on that work, now with a clear, modern license. It follows Microsoft’s earlier release of GW-BASIC, which descended from the same lineage and shipped in the original IBM PC’s ROM. That code evolved into QBASIC, and later Visual Basic, which remains a supported language for Windows application development to this day. From the blinking cursor of 1977 to FPGA builds in 2025, BASIC still fits in your hand. Now, for the first time, this influential 6502 version is truly yours to explore, modify, and share.

9 months, 1 week

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List of PDP-8 omnibus boards available at VCFMW or shipped.

by Paul Anderson

M1705 M518 M7741 M8342 M835 M8350 M8360 M8357 M8365 M8366 M837 M839 M841 M847 M849 M860 M8650 M8659-YA M865 M8652 M8653 M8655 M866 M868 M884 M885 M880//H241 MR8E-EC Also CR8- an actual DEC card reader interface, dec industrial control equipment,EMEX paper tape interfaces, and other dec compatible boards including memory.

9 months, 2 weeks

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WIN 95

by Murray McCullough

Microsoft released WIN 95 on this day 30 years ago. It was a game changer for the average PC computer user but more important than Windows 3.1? Not so sure. Happy computing, Murray 🙂

9 months, 2 weeks

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The Sharp PC-5000 Video

by Steve Lewis

Hey all, after a couple years of prep (weekends here and there), I've finally finished a full coverage video about the Sharp PC-5000. It's not the most meaningful system in history, but it also shows the "MS-DOS 2.0 experience" and bubble memory usage. Various folks around here helped me figure this system out and get some of the equipment, very much appreciated the willingness-to-help community here. Video is on YouTube titled as: Sharp PC-5000 and MS-DOS 2.0 Usage Demonstration (EDLIN, CTTY, MASM, BASIC, Pascal, WordStar, more!) Or link... https://www.youtube.com/watch?v=dHPiomuWDmk And to those who can't use YouTube for whatever reason, I've started also uploading over on Rumble as an alternative source: https://rumble.com/v6ybfky-sharp-pc-5000-and-ms-dos-2.0-usage-demonstration… I'll be at VCF MW coming up, hoping to pick up another system that I've been wanting to explore for a long time! Not sure yet it works, but that's how the hobby goes :) - Steve (voidstar tech / Xiphod)

9 months, 2 weeks

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Message trimming/formatting

by Marvin Johnston

There seems to be a LOT more people who don't believe in trimming or formatting their copies of the messages they are replying to. I see that kind of obvious disrespect for other readers, and ignored it for a while. But it is getting worse. Please format/trim when replying. Marvin

9 months, 2 weeks

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5155 lugable

by Bill Gunshannon

I finally got the missing keyboard and now it is time to try and revive it. A couple quick questions. It has a board in it called IBM PC INTERFACE with the numbers 170-18-165 and CIL18-16 printed on it. It has a 50 pin connector on the bracket end. If I take it out the machine dies almost immediately doing the POST. Tried Google with no luck. Anybody remember what it is? Next problem. 1701 error. Light on MFM drive flashes 3 slow and 4 fast continuously. Being as this machine was known to work when it was last shut down any suggestions? Could it be a stiction problem and the disk just isn't spinning up? (Can't tell by listening as the fan is pretty loud. Not bad just louder than any good disk I have ever heard.) And then one other not related to a problem. Being an original PC owned by users and not geeks is it likely that the floppy controller is one that can handle other formats (like TRS-80) and maybe even 8"? And just to wrap it up. What are the chances of finding an external drive or even a cable that could be made to connect to an external drive? Really hoping to get it to run. Would love to see what the Psychology Department had on it. At least WordPerfect as there is one of those function key templates taped on the keyboard. bill

9 months, 2 weeks

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Re: Tesla's Forgotten Founder Speaks Out - Exclusive w/ Martin Eberhard

by Shoppa, Tim

Frank wrote: > I wasn’t around back then ;) But I think the big problem with > steam tractors was since they were so heavy they would sink into > the fields. I don’t think that was an issue really solved until gas > powered tractors came around. We're getting off topic but I want to interject that if you want to see operating steam tractors, stationary steam engines, and lots more, get to Mt Pleasant Iowa RIGHT NOW for the annual Old Thresher's Reunion which starts TODAY. I note that when the Old Thresher's Reunion first started in 1950, the steam tractors being run there were only 40-50 years old, not too dissimilar to how an Apple II or PDP-11 is today. https://www.youtube.com/watch?v=hs4L2nSqCL4 https://www.oldthreshers.org/other-events/steam-school/ Tim N3QE

9 months, 2 weeks

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Tesla's Forgotten Founder Speaks Out - Exclusive w/ Martin Eberhard

by Kirk Davis

Interesting for Tesla’s early history, but skip to 49:00 for a nice rack he is putting together with an 11/20. https://youtu.be/88KHfX_kPIY He also appears to be on the cctalk list.

9 months, 2 weeks

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Need 3.5" drives?

by Van Snyder

I have some 3.5" drives I don't need. One 350 GB PATA Three 320 GB SATA One 500 GB SATA Yours in exchange for a PDF of a shipping label from Van Snyder 2229 Shields Street La Crescenta, CA 91214 Local pickup also OK. Just say which ones you want. They all have smartctl reports that claim they passed.

9 months, 2 weeks

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CII1040 ..what exactly is this?

by Holm Tiffe

Hi guys, I'm somewhat sorting my stash of forever laying around parts and there are 12 pcs from those: https://www.tiffe.de/images/CII1040.jpg That are two PNP BJTs in an TO can..and I think they are old. I've desoldered them years ago. Most of them have an TI logo printed on top. I could'nt find any data..can someone help here? Thx, Holm -- Technik Service u. Handel Tiffe, www.tsht.de, Holm Tiffe, Goethestrasse 15, 09569 Oederan, USt-Id: DE253710583 info(a)tsht.de Tel +49 37292 709778 Mobil: 0172 8790 741

9 months, 3 weeks

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