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kens 8 hours ago [-]
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 3 hours ago [-]
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.
smallstepforman 3 hours ago [-]
While I’m on alternative histories, if Jack Tramiel didn’t piss off Chuck Peddle, it would be MOS/C= in Intels pisition today.
rswail 2 hours ago [-]
That was the 1980s, PDP-11s were the 1970s.
mrandish 2 hours ago [-]
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 2 hours ago [-]
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 1 hours ago [-]
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.
throwaway27448 3 hours ago [-]
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 6 hours ago [-]
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 5 hours ago [-]
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 41 minutes ago [-]
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.
mrandish 2 hours ago [-]
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 3 hours ago [-]
BASIC was developed on GE mainframes.
ggm 5 hours ago [-]
I'd argue the pdp8 opened the floodgates. That's when the cost of digital computing dropped to the point a research grant or even just discretionary spending in a university department could pay for one, and you didn't need a special room and power supply.
the 11 was when it became more useful. But the 8 was how people realised you could move beyond a calculator to a computer.
larsbrinkhoff 3 hours ago [-]
Then maybe also give a nod to the LINC, showing DEC a small 12-bit computer could be made.
ErroneousBosh 3 hours ago [-]
> That's when the cost of digital computing dropped to the point a research grant or even just discretionary spending in a university department could pay for one
I've mentioned this before, but the PDP8 launched in the US about the same time as JCB launched their first (and arguably the first really practical and useful) backhoe loader in the UK, which was about three and a half grand at the time.
Can you imagine the paradigm shift with either of those machines? Not just it's possible to do that work, but you can do that work with *your own one*.
At some point someone has looked at a shiny new PDP8 or a JCB 3C in the showroom and gone "you know what, I'm just going to buy one", and got the chequebook out.
ggm 2 hours ago [-]
That's an amazing parallel. So much to think about how it changed dynamics of work replacing manual ditch digging and wheelbarrows.
rswail 2 hours ago [-]
My first ever computing experience was in 1977 in year 9 at high school where we were lucky enough to have a PDP-11/10 with 16K(!) and 3 ASR-33s and a VT-52.
Learned how to program in octal on the front panel. I've still got an old front panel (the rest is a rotting collection of wirewrap boards in my garage).
It had a multi-user basic that left out string functions if you went multi-user. You loaded the bootstrap via the front panel, which read the "absolute loader" from paper tape on one of the TTYs, which then read the BASIC interpreter from the same source.
I still have the small reference card with the instruction set and some old paper tapes around somewhere.
The whole structure of the registers with R7 as the PC and R6 as the SP and the various addressing modes was just elegant.
We used to make jokes that your programmed a PDP-11 with 3 fingers (octal) and a VAX with 4 (hex).
nickcw 2 hours ago [-]
I'm not old enough to have used a PDP-11 so I read through the assembly code description with interest.
Wow, it seems so modern. I've used a lot of assembly languages over the years but I'd feel immediately at home here. Nice sensible orthogonal instruction set with enough registers and a stack pointer. It reminded me immediately of ARM assembly - what a breath of fresh air that was when it came it.
I never realised quite how much influence the PDP-11 had on computer architecture. I knew about it's software legacy but I suspect that was enabled by it's ground breaking architecture.
not2b 6 hours ago [-]
It was the preferred lab computer in the mid to late 1970s and into the 80s. I got my first job because I knew PDP-11 assembly language, and worked with both DEC's operating systems for them (RT-11 and RSX-11) and later Unix (the lab I worked with had some machines running Version 6, though Version 7 was the first that I used seriously. It had a very clean and symmetric instruction set that used the program counter as if it were another general purpose register. I had an LSI-11 board (the single-board version of the machine) with 4K 16-bit words of core memory and a paper tape punch with a tiny loader in ROM to read in the tape and peek and poke memory, and I'd sometimes initialize the core memory to a known state by running the one-instruction program
mov -(pc), -(pc)
or 014747 in octal. It would fill all of memory with 014747.
mrandish 4 hours ago [-]
> It had a very clean and symmetric instruction set
Indeed. Motorola's 68000 CPU took so much inspiration from the PDP-11's ISA, it was almost a spiritual successor. The 68000's 8/16-bit little brother, the 6809, widely considered the most powerful 8-bit CPU ever - was also heavily inspired by the PDP-11.
I built the PDP-11/70 emulator that controls the nuclear reactors in Ontario. That was 20 years ago and I'm probably still the youngest person who can read PDP-11 assembly (and the raw octal)
ErroneousBosh 3 hours ago [-]
There's a decent chance you're younger than me, but I can still read it. Coincidentally about 20 years ago I got asked to fix a bug in some PDP11 code that ran on real hardware because it was tripping up an emulated system. Nothing wrong with the emulator as such, it was just a logic bug in the program that they no longer wanted to work around.
I made the fateful mistake of saying "Sure, sounds fun, how hard could it possibly be...?"
"PDP-11 with UNIX opened the floodgates for inexpensive interactive computing, which then led to an explosion of office productivity. "
Well before we get too misty eyed: "inexpensive" needs looking at "for inexpensive interactive computing".
I'm not old (55) enough to have really got to grips with a PDP11. I do still own (yes: present tense) a C64 from 1986. The C64 was bought by my dad via the NAAFI in West Germany so I have no idea what it costed. Let's wind forward a bit:
I had a 80286 based PC in 1987ish with 1MB of RAM, 20MB RLL hard disc. The graphics card (ISA) had a whopping 512 bytes of RAM. That thing costed about £1200. I added a 80287 later at about £120 so I could run a pirated copy of AutoCAD.
In 1990ish I had a 80486 with 4Mb RAM and 40MB HD - that costed something like £1600.
Nowadays £1600 will buy quite a decent laptop and 35 years of inflation.
pezezin 2 hours ago [-]
> The graphics card (ISA) had a whopping 512 bytes of RAM.
I think you are missing a "kilo" there...
EvanAnderson 6 hours ago [-]
There's a parallel worldline out there where the PDP-11 made the transition into a desktop PC[0] and the IBM PC didn't take over the world. In that worldline our servers are from the PDP-11 lineage, and not the IBM PC.
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.
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).
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.
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.
I would argue that Intel was so highly influenced by Datapoint due to sheer proximity and early inexperience in the field.
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.
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.
the 11 was when it became more useful. But the 8 was how people realised you could move beyond a calculator to a computer.
I've mentioned this before, but the PDP8 launched in the US about the same time as JCB launched their first (and arguably the first really practical and useful) backhoe loader in the UK, which was about three and a half grand at the time.
Can you imagine the paradigm shift with either of those machines? Not just it's possible to do that work, but you can do that work with *your own one*.
At some point someone has looked at a shiny new PDP8 or a JCB 3C in the showroom and gone "you know what, I'm just going to buy one", and got the chequebook out.
Learned how to program in octal on the front panel. I've still got an old front panel (the rest is a rotting collection of wirewrap boards in my garage).
It had a multi-user basic that left out string functions if you went multi-user. You loaded the bootstrap via the front panel, which read the "absolute loader" from paper tape on one of the TTYs, which then read the BASIC interpreter from the same source.
I still have the small reference card with the instruction set and some old paper tapes around somewhere.
The whole structure of the registers with R7 as the PC and R6 as the SP and the various addressing modes was just elegant.
We used to make jokes that your programmed a PDP-11 with 3 fingers (octal) and a VAX with 4 (hex).
Wow, it seems so modern. I've used a lot of assembly languages over the years but I'd feel immediately at home here. Nice sensible orthogonal instruction set with enough registers and a stack pointer. It reminded me immediately of ARM assembly - what a breath of fresh air that was when it came it.
I never realised quite how much influence the PDP-11 had on computer architecture. I knew about it's software legacy but I suspect that was enabled by it's ground breaking architecture.
mov -(pc), -(pc) or 014747 in octal. It would fill all of memory with 014747.
Indeed. Motorola's 68000 CPU took so much inspiration from the PDP-11's ISA, it was almost a spiritual successor. The 68000's 8/16-bit little brother, the 6809, widely considered the most powerful 8-bit CPU ever - was also heavily inspired by the PDP-11.
I built the PDP-11/70 emulator that controls the nuclear reactors in Ontario. That was 20 years ago and I'm probably still the youngest person who can read PDP-11 assembly (and the raw octal)
I made the fateful mistake of saying "Sure, sounds fun, how hard could it possibly be...?"
Well before we get too misty eyed: "inexpensive" needs looking at "for inexpensive interactive computing".
I'm not old (55) enough to have really got to grips with a PDP11. I do still own (yes: present tense) a C64 from 1986. The C64 was bought by my dad via the NAAFI in West Germany so I have no idea what it costed. Let's wind forward a bit:
I had a 80286 based PC in 1987ish with 1MB of RAM, 20MB RLL hard disc. The graphics card (ISA) had a whopping 512 bytes of RAM. That thing costed about £1200. I added a 80287 later at about £120 so I could run a pirated copy of AutoCAD.
In 1990ish I had a 80486 with 4Mb RAM and 40MB HD - that costed something like £1600.
Nowadays £1600 will buy quite a decent laptop and 35 years of inflation.
I think you are missing a "kilo" there...
[0] https://en.wikipedia.org/wiki/DEC_Professional_(computer)
I loved that computer. Like a fool, I sold it for $25. There's a picture of it on my X profile.
The -11 had an instruction set that fit on one page.
Downside, programs are pretty simple that run in 64k. And extended addressing in any form, sucks.