[kens]

I'd suggest the Datapoint 2200 as the most influential minicomputer of all time since half of you are using an instruction set based on it and it is largely responsible for the creation of the microprocessor.

Now mostly forgotten, the Datapoint 2200 was a programmable desktop computer introduced in 1970. It had a processor built from TTL chips, along with shift-register memory from Intel. Datapoint discussed with Intel and Texas Instruments the possibility of building a single-chip processor to replace the board of TTL chips. TI was first with the TMX 1795 processor, followed by Intel's 8008, both copying the Datapoint 2200 instruction set.

Datapoint decided that these chips didn't have enough performance and fatefully gave up rights to them. TI tried to sell the TMX 1795 to Ford, but got nowhere and abandoned the chip. Intel decided to sell the 8008 as a standalong microprocessor, which was used in early personal computers like the Mark-8. Intel improved the 8008 to form the 8080, then made a somewhat compatible 16-bit version, the 8086, which started the x86 architecture. (Because the Datapoint 2200 was little-endian (to use shift-register memory), x86 is little-endian.)

To summarize its influence, without the Datapoint 2200, the microcomputer industry would have been greatly delayed (since the 4004 wasn't suitable for a personal computer) and x86 wouldn't exist.

[smallstepforman]

The 6809 (and its clone the 6502) would also be strong contendors. And if Motorola were 6 months faster with the successor 68000 compared to Intels 8086, the IBM PC would be 68000 based and Intel would today be known as a memory chip company. We’d be big endian with no legacy in 2026 of segmented memory architecture in mainstream processors. And with big 3 companies using 68000 (IBM, Apple and C=), we definately wouldnt have WinTel.

[rswail]

That was the 1980s, PDP-11s were the 1970s.

[mrandish]

The influence was what the people who learned computing in the 70s on PDP-11s at university, went on to do with what they'd learned in the 80s.

Also, the 6809 shipped in 1978. Little known fact, the Macintosh was going to be based on the 6809 and Jef Raskin's team had 6809 Mac prototypes running before Steve got Motorola to drop their price on the 68000 (in part because Moto was panicked over losing out on the PC).

[rswail]

Agreed, just saying that the PDPs were where a lot of the people developing micro computers cut their teeth eg CP/M looks a lot like RT-11.

Minicomputers like the PDP-11 begat microcomputers around 8080s, Z80s, 6509s, 6502s.

"Home" microcomputers started around 1977/78 with the Apple ][ and TRS-80 and PET.

[mrandish]

For sure, by volume the impact of the PDP-11 was almost entirely through micros and workstations because they were taking over so fast. Although, Unix and C did spread like wildfire from the PDP-11 to other minis. In fact, C was originally created for porting Unix.

In terms of timing, the PDP-11 shipped in early 1970 and was an immediate best-seller. Back then, students didn't get much hands-on computer time until their final two years so by the mid-70s its influence was already being felt. The 6809 was being designed in 1975 and the architecture was clearly inspired by the PDP-11's orthogonal ISA, interrupts stack handling, etc.

[classichasclass]

The 6502 isn't a 6809 clone; it was largely inspired by the 6800.

[smallstepforman]

My mistake. I remember reading the C= book “on the edge” and there was a chapter about how 3 chip designers at motorola couldnt get management to pursue low cost version of 6800, so they made 6502 in a startup called MOS in 1975.

[smallstepforman]

While I’m on alternative histories, if Jack Tramiel didn’t piss off Chuck Peddle, it would be MOS/C= in Intels pisition today.

[timbit42]

How so?

[chasil]

What is not well-known is that:

a) the PDP-11 CPU was also implemented in TTL logic, like the Datapoint,

b) there were later implementations of the PDP-11 as NMOS microprocessors:

https://en.wikipedia.org/wiki/DEC_T-11

https://en.wikipedia.org/wiki/PDP-11#LSI-11_integrated_circu...

c) the VT100 terminal was based on the Intel 8080 microprocessor

https://en.wikipedia.org/wiki/VT100

There was appreciation and exchange between Intel and DEC.

[HarHarVeryFunny]

Apparently Motorola had started work on their PDP 11 inspired 6800 in 1971, same year the Datapoint 2200 terminal was released, and would end up shipping it in 1974, same year Intel released their 8008 successor the 8080 (which the Altair 8800 was based on), so even without Intel's calculator (4004) and terminal (8008) chips we'd still have had single-chip LSI CPUs in a similar time frame.

[throwaway27448]

You can see the influence of the PDP-11 on C more than any other ISA. That alone I think qualifies it as the most influential microprocessor of all time.

[themafia]

The Internet (mostly), the C language, the Unix Operating System were all developed and deployed on PDPs. The BASIC language /and/ an 8080 emulator was developed on a PDP in order to deploy to the Altair.

I would argue that Intel was so highly influenced by Datapoint due to sheer proximity and early inexperience in the field.

[kens]

I don't think you can count PDP-10 things (Internet, BASIC, 8080 emulator) to support the influence of the PDP-11, since they were completely different computers. The PDP-10 was a 36-bit mainframe, while the PDP-11 was a 16-bit minicomputer.

[phire]

PDP's lack of naming really confuses things, they essentially just numbered the computers by release date.

There are like 3-5 completely different family trees of computers in their numbering scheme (depending on how you count), all of them are notable in some way.

[cesaref]

Yeah, there were two busses, and the bigger ones were certainly rather impressive. I built a PDP-11/23 out of spare bits gifted from a university physics department in the late 80s, and it was awesome, but nothing like an 11/70 or anything like that!

[mrandish]

While I just missed out on minis and mainframes (starting with early 8-bit micros and 4k RAM), as a retro fan who's read deep into the Datapoint 2200, Intel, TI saga, I agree the DataPoint is a heavy hitter easily deserving of the title. But measuring 'most influential' is tricky because it depends on whether we use a hardware or software yardstick. For hardware, the Datapoint is a slam dunk for its influence on, arguably, the first 8-bit CPU (8008) and its eventual DNA impact on the CPU gene pool (x86).

For software, the PDP-11 has an ironclad claim on operating systems (Unix - which gestated on the PDP-7 but was born on the PDP-11) and languages (C), with a strong 2nd place in hardware via its heavy influence on the venerable Motorola 68000 family.

I also agree the PDP-10 should be part of this conversation as it was certainly influential. My second-hand sense from reading retro history, is the PDP-10 was beloved, if not revered, by nearly all who touched it. It was indeed an aspirational North star, but its eventual influence was both delayed and limited. Limited because it was a monstrously powerful mainframe with an equally monstrous price, selling only 1,500 units compared to the PDP-11's 600,000. This limited those who saw it to major research institutions (MIT, Stanford, etc) and large corporations. And delayed because the PDP-10's incredible power allowed some futuristic concepts to be experimentally prototyped on it first, but the advanced operating system and networking ideas pioneered on the PDP-10 would have to wait for 32-bit power to arrive on desktops in the late 80s and 90s.

Personally, I give the nod to the PDP-11 for biased (but justified) reasons. Everyone in 80s computing knew of the PDP-11, whereas I was already a retro collector before I'd ever heard of the Datapoint and its valid claims to the title (and I still can't name its operating system or any languages and applications born on it). Unfair... but is history is rarely fair. And in any dead-even tie, whatever side x86 is on must lose because, to me, it will forever bear the WinTel beige stain of being the asteroid that snuffed out a Cambrian explosion of diverse platforms, OSes and apps in the late 80s to mid-90s.

[larsbrinkhoff]

BASIC was developed on GE mainframes.