Jcrow-it.com

10/06/2026

Levity™ from RLP | Gravity Free Manufacturing™ | 3D Printing | Rapid Liquid Print Co. https://share.google/tCJLEiPRwEEeC2jLC

08/25/2026

https://www.facebook.com/share/v/1Bj3M1jEzP

Neat!

08/07/2026

Ethernet explained.

Dave explains Ethernet from the outside in and back again! Check...

06/02/2026

A couple simple websites have been deployed for clients in the last month. Doesn't matter to me what content you wanna host. I can help build you the frame work to make it happen. Tree1four.com , TeamNoTill.com thanks for letting me help you with your build outs.

05/08/2026

04/24/2026

The original IBM PC's 640KB RAM limit wasn't a hardware constraint — it was a map. When IBM designed the PC in 1981, they divided the 8086's 1MB address space like a floorplan: the bottom 640KB was for programs, and the top 384KB was reserved for video memory, ROM BIOS, and expansion cards. Bill Gates never actually said "640K ought to be enough for anyone" — that quote is apocryphal. The real problem was that IBM hard-coded the memory map into the BIOS, and every piece of DOS software after that assumed it. By the late '80s, entire cottage industries popped up around memory managers like QEMM and EMM386 whose sole purpose was to claw back usable RAM from that upper 384KB. It took until the 386 processor's protected mode and eventually Windows 95 to finally break free of a layout decision made in a single meeting over 40 years ago.

04/20/2026

decided to give the site a facelift!!

JCrow IT Services - Expert IT solutions in St. Charles, Missouri. Server administration, network security, cloud services, and more.

04/08/2026

The "Halt and Catch Fire" instruction was a real CPU opcode.

On early Motorola 6800 and some other processors, opcode 0x9D had no defined function — but executing it would cause the processor to fetch and execute instructions as fast as it possibly could, with no regard for logic or output, generating so much heat it could literally damage the hardware. Engineers nicknamed it HCF — Halt and Catch Fire. It wasn't documented, wasn't intentional, and wasn't supposed to exist. It was just what happened when the chip hit an undefined state and went haywire.
The term lived on as a dark joke in hardware engineering circles for decades — and of course became the name of the excellent AMC show about the PC era. But the original was very real: a CPU instruction whose only job was to potentially destroy itself.

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03/31/2026

The original IBM PC was never supposed to run DOS.
When IBM rushed the 5150 to market in 1981 to compete with Apple, they went to Digital Research to license CP/M — the dominant OS of the era — but the deal fell through (legend has it Gary Kildall was out flying his plane when IBM showed up). IBM pivoted to a tiny Seattle company called Microsoft, who didn't actually have an OS. Bill Gates bought QDOS ("Quick and Dirty Operating System") from a developer named Tim Paterson for $50,000 flat — no royalties — rebranded it as PC-DOS, and licensed it to IBM while quietly retaining the right to sell it to anyone else as MS-DOS.
IBM thought the real money was in hardware. Microsoft knew the real money was in software. That $50,000 acquisition — and IBM's oversight — is arguably what made Microsoft the most valuable company on earth for much of the next four decades.
Tim Paterson's $50k is widely considered one of the worst deals in tech history.

03/18/2026

The Border Gateway Protocol (BGP) was literally designed over lunch in 1989, sketched out on "two napkins" by engineers Yakov Rekhter and Kirk Lougheed. It has no built-in authentication — routers simply trust that the network prefixes advertised by other networks are legitimate. This is why BGP hijacking is still a real threat today: in 2010, China Telecom accidentally (or not) rerouted roughly 15% of global internet traffic through their network for about 18 minutes. In 2022, a misconfiguration at a small ISP briefly knocked Cloudflare offline. The fix — RPKI (Resource Public Key Infrastructure) — exists but adoption is still incomplete decades later. The whole global internet is essentially running on a 35-year-old honor system.