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Thoughts on minicomputer to microcomputer transition (PDP to Macintosh)

The Marcus Wigan benchmark list paper I have referred to in the past might be helpful. It covers a very wide range of systems; one list has a CDC Cyber and Tandy Pocket Computer as the performance bookends. There are also 6 different 4 MHz Z-80 benchmarks differing only in the BASIC used. Wang 2200 is there. Versions of the selected benchmarks were also ported to Pascal, Fortran, and S-Algol providing even more comparison options. Those preferring Forth will be disappointed with its absence.
 
I do think it's fair to benchmark a system "as-is" or "out of the box" and not with whatever potential upgrades or mods could be made (in hardware or software). Isn't that's how cars are evaluated, on its merits out from the factory?

And floating-point is kind of useless for finance type software, to correctly increment and round out pennies (rather than some approximation). But FP is useful for astronomy software (earliest computer controlled planetarium I'm seeing is from 1983), or construction material cost estimates.
 
You are aware, of course, that several systems use decimal floating point in their BASIC for just that reason? Don't assume that floating-point implies binary math. Decimal math was an important part of many mainframe instruction sets. S/360 had it; the lowly 1620 CADET in you benchmark table was a variable word-length decimal machine.
Early on, IBM offered two distinct system lines; one employing decimal math, the other binary. The binary systems were thought of as "scientific" as opposed to "commercial". Consider, say, the IBM 709 vs. the 705, or the 7090 vs. the 7070.
The IBM 360/20 only has a few simple 16-bit math functions, but a full set of memory-to-memory decimal ones.

Since COBOL requires decimal math in several types, all systems running it had to implement decimal math somehow. Some of the schemes for doing parallel decimal operations on a binary (multibyte) word were quite clever.
 
Oh yes, much respect to the decimal computation systems of the 50's, and the science of representing very large numbers (e.g. larger than would fit on a single register) and doing computations with those. Makes me think of the Medici Banks of the 1400s and their number crunchers -- getting the accounting quickly, and with the integrity of doing it correctly, is important business. And that's the art of software -- coming up with clever ways to efficiently use the available hardware (porting an existing approach to a new instruction set might work, but might not be optimal to that new system).


One more update, with a question...


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How realistic was it to have 5.25" disk drives on the SOL-20 (or Altair or clones) in 1976? I know 5.25" form factor was fairly new in '76, very early days of it. I mean in terms of being able to walk into "the computer store", isn't that more 1978-ish? Would it have just been extremely expensive in 1976? Where would you even get the media?
 
5.25” floppy drives were first available for sale in late 1976 for a starting list price of $400 for a bare drive but, yes, it’s unlikely you saw many in the wild before 1977. They did catch on very quickly, however, and by 1978 there were ten different manufacturers using the format.

Processor Tech’s “official” drive system for the SOL-20 was a dual 8” drive called the “Helios” using a unique mechanism that turned out to be a boondoggle that helped kill the company. (And I don’t think it was available before 1977 either.) The reason you see so many SOLs with 5.25” drives is Northstar introduced a cheap and reliable controller for them in early 1977 that for a time was an extremely popular entry level option for S-100 systems. (A Northstar controller and a couple SA400’s might cost well under half what a typical 8” setup went for.)

Anyway, sure, long and short of it is if you really want to picture of a non-anachronistic disk system from 1976 it should probably have 8” drives.
 
How realistic was it to have 5.25" disk drives on the SOL-20 (or Altair or clones) in 1976? I know 5.25" form factor was fairly new in '76, very early days of it. I mean in terms of being able to walk into "the computer store", isn't that more 1978-ish? Would it have just been extremely expensive in 1976? Where would you even get the media?
Not very. Disk Trends lists the world wide shipments of 5.25" drives in 1976 as one thousand. 1979 has the shipment level as 426,400 of single sided and 17,400 of double sided drives. The good news is that there were a number of disk controllers available in 1976 though not as convenient as they became. http://www.retrotechnology.com/dri/first_floppy.html seems like a good starting point in researching controller development.

Looking at media, in 1976, there limited options for 5.25" disks. Shugart had what is listed as the SA104 and SA105 (soft and hard sector respectively), Wang offers the Shugart media as Wangco 820, BASF has the 606 hard sectored disk, and Micropolis had the 1081 which was also hard sectored. I think the BASF and Micropolis disks were interchangeable with the SA105. Note that Micropolis had already introduced their 100 TPI design so the disks created there could not be read on the Shugart or BASF drives.
 
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If one were to ever do a painting or even a tapestry of some of the (computer) highlights of this era -- you'd get bogged down in some of the trivia (which is why I still didn't put the Sphere-1 in -- it was a very good start, but just didn't get the sales numbers - it definitely was a contender, but for whatever reason, it fizzled as a product and becomes part of the back story; the same could be said for the KINBAK-1, since not even 100 of those were sold? however there is room for the KINBAK, so I kept it in).

Also, in hindsight, I realize this should not be thought of as a "transition" of mini's to micros. "Mini's" continued on till the 1990s, and there are plenty of "cabinet" systems being built and deployed today (subjective if anyone wants to still call those minis, or just server farms). I guess a better phrase is "dawn of the micros". End of 1972 was the end of the Apollo mission, and some excitement remained from all that. (I was browsing through the Apollo AGC code that's now available in github, like the coordinate transformation routines and Lat/Lon conversions -- neat stuff! ) So big-expensive corporate computing didn't end, but clever engineers (or their kids) wanted to bring that capability home.



My only reference to the 8" drives was the larger disk media at the top left, with that media coming about in 1972. The Wang (and others) had 8" drives (as standard offering in products) by mid-decade 1975, then the follow up IBM 5110 had it later in 1978. As with most things - engineers show "the possible" and then there is some lag before folks figure out how to integrate it into a product generally about a season later.

But my take is, practically speaking, that 8" format was never a part of home computing, i.e. not really ever part of the "micro" community? I'm sure someone had one of them setup in their garage or shed, just since it was technically possible (and inevitably someone would come across an office that had discarded their 8" drive). But the early micros maybe didn't generate enough data to make the expense of an 8" worthwhile? (and too bulky for The Computer Store to carry)

For sure, I recall lawyer offices and banks using 8" even up through the 80s.

I liked the rumor that Wang suggested the 5.25" media should be "about the size of a table top napkin" -- that is fitting, but it's like the Gate "640K memory" quote, it's something they never actually said.


(btw I've read more about the Tektronic 4051 and how that series was used by the US Navy, and was surprised it used the 6800 microprocessor, I hadn't realized that)
 
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you'd get bogged down in some of the trivia (which is why I still didn't put the Sphere-1 in -- it was a very good start, but just didn't get the sales numbers - it definitely was a contender, but for whatever reason, it fizzled as a product and becomes part of the back story

Then why in the world did you ever have the Apple I on there, which by reasonable estimates of Sphere’s output sold less than a quarter as many?

But my take is, practically speaking, that 8" format was never a part of home computing, i.e. not really ever part of the "micro" community?…

Thousands upon thousands of CP/M computers were sold with eight inch drives well into the 1980’s. And these were all “microcomputers“ by any standard definition of the word. Are you making a chart of “Micro“ computers or “Home” computers? You can kind of make the case that 8” floppies were never really mainstream for *home* computers (although plenty of machines could technically be hooked to them) but that’s a different chart. Why in the world do the Wang 2200, Tektronix 4051, or IBM 5100 belong on a “home computer” chart?

I guess I’m starting to question what the point of this thread is if you’re just going to apply random preconceived filters to every historical fact.
 
Fair point. It is to show the blending between "personal computers" and what became "home computers" (in terms of actual fielded products) And, to also show that part of that blending involved these "headless" microcomputer boxes (but not to imply a linear "this led to that"). Some younger co-workers did have an impression that "personal computing" didn't begin until the 1990s - which I thought was an interesting perspective: how easy does a computing system need to become to use for non-technical users to embrace it? I always felt the Trinity fell into that category, which not everyone agrees with either (but I think it's worth remembering that the Trinity didn't just appear out of divine genius, but as an honored roll up of lots of corporate work that proceeded it -- the "$10k tier" that sat between the $100k minis and the early-kits).

So absolutely right, not a story of the microcomputer in of itself. But more from the user/consumer perspective - nobody could afford a "personal computer" that cost more than a house, and a $500 box of electronics wasn't quite there yet either. But at some point, non-technical people found utility in these devices - maybe that point was Stephen King using the Wang in mid-1970s, or maybe it was when grandma started using Genealogy software in 1981. But we need more outreach if people thought it was the 1990s :D



To me it's interesting since I see so many parallels with the development of the piano in the 19th century (well, moreso the upright specifically). Big bulky grand pianos (but very exquisite, for royalty). Then people strove to make those personal (smaller, portable), once they understood the general principle. Composers arose to write the "software" (music sheets) that made them sought after instruments, and they also had to seek publishers to help distribution (and ultimately get payment for their work -- akin to the 1975 "letter" moment). The first uprights weren't very good (Thomas Jefferson returned one under warranty c.1801, went the harpsichord route instead), but it was about a 40 year refinement (materials and design for escapement, steel types for the strings), from something like 60" down to 40" upright cabinet (compact enough to finally put on a boat -- since turns out entertainment on long voyages is worth it, and reliable enough that the hammers just didn't snap after a few weeks) - and eventually a piano in every home happened (sort of, at least enough that the market crashed with excessive amounts of low-quality uprights), which all then got trumped by the advent of radio.

Sorry for the tangent, I do thank you for your time and discussion; learned and reminded of a lot.
 
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As my daughter said to me "Fixed it!"

Mural_History_of_PersonalToHomeComputers.jpg

We were talking about the prior posts, and she made some alterations.

Files on github, along with a link to the KRITA file with the layers if anyone wants to make alterations.



Then we prepared some notes on context (such as "notable mentions" of other systems we wanted to include):




Happy Holidays to all!
 
Naturally, the "consumer-grade computer" industry was supported in parallel by lots of "amateur computing" going on. I came across this old article from 1978:


As a quick summary from this article:

Code:
May 5 1966: (Steven B Gray founded Amateur Computer Society)
      1966: book "We Built Our Own Computer" by A B Bolt
(not much for 1967 - some CQ magazine kits that were never built)
April 1968: ECHO IV (Jim Sutherland; 8K, 18 instructions, 160 kHz)
(no highlights for 1969/1970 - but CTC/Datapoint was active around this time on their 3300)
      1971: 1000 Minutemen I missile guidance processors became available in surplus
      1971: first "computer kit" (Louis E Frenzel, 15 instructions)
      1971: Kenback-1 (65 instructions, audio cassette storage)
      1972: Don Tarbell - editor program and assembler program
early 1972: opening of "several used computer equipment stores"
      1972: 8008, TTL price drops, 1101 programmable memory (and the 1702)
      1972: Roger Amidon's 4-bit "Spider" (TTL, RTTY, featured in BYTE April 1977)
Sept. 1972: Hal Chamberline, HAL-4096 (surplus IBM 1620 core, 16-bit system)
Sept. 1972: Electronic Design article, 1024 ASCII chars on a TV set
  May 1973: EPD System One kit
Sept. 1973: Don Lancaster TVT-1
 Late 1973: Scelbi-8H ($2760 for 16KB, cassette IO, ASCII keyboard, o-scope output), defunct Dec. 1974
      1973: PDP-8A under $900
 July 1974: Radio Electronics Jonathan Titus, Mark-8 (est. 500 units built)
 Oct. 1974: SwTPC TVT-II kit and ASCII keyboard ($220 total)
April 1975: first deliveries of Altair 8800 (kit had no IO, 10k sold by end of year per MITS)
April 1975: first computer-club meeting (Bob Reiling, Gordon French)
 Fall 1975: MITS 4K/8K BASIC interpreters
 Fall 1975: SwTPC 6800-based microcomputer
(end of first decade of "amateur computing")

Other notes:
1969: Busicom/Intel contract for printer-calculator ($200 4004)
1971: Datapoint/Intel relationship ($200 8008, interrupt capability), Intel introduces 1101 and 1702
1972: National Semiconductor introduces IMP-16 ("user definable instruction set")
1973: Intel 8080 ("still required an external clock and multiple power supplies", vs 6800 required one TTL power supply)
1975-1976: "3rd gen microprocessors" Z-80, enhanced 8080 (on chip clock), 6502, TMS9900/TMS9980 (16-bit)
1977: "4th gen microprocessors" (actual "microcomputers in a single IC" -- microprocessor, ROM, programmable memory, IO on one chip)

Sadly, the Sphere-1 isn't mentioned here - although, I suppose it's not in the "amateur" category as they were trying to become a consumer product.

This is a July 1978 article, which I think it is legit Although, the article is followed by an advertisement for a Terrapin "TURTLES", which isn't all that different than a modern day robot-kit that can "map rooms, ...dance, explore Artificial Intelligence" except that it uses an S-100 bus interface :D You'd think 45 years later, we'd have robot home-kits that could walk your dog by now :D Well, they can at least vacuum your floors fairly reliably.
 
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