History of MOS 6502 [video]
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a) There were really two chips done, the 6501 and 6502. The difference was in a few pins, the 6501 was fully pin-compatible with the 6800, the 6502 was easier to use in a system design since it did not require a two-phase non-overlapping 5V rail-to-rail clock.
b) The 6501 cost $20, the 6502 cost $25. Quantity 1. They ran at 1 MHz. You could send a letter to the company in Pennsylvania, with a check enclosed, and buy 1 chip for that price. Try buying one CPU chip from Intel nowadays. :)
c) The lawsuit by Motorola that he mentions resulted in MOS agreeing to discontinue the 6501. But that didn't matter much for 99% of their potential customers. First, the pin differences were very minor. Second, the TTL-level clock input in the 6502 meant that an external clock driver chip wasn't needed.
[1] http://en.wikipedia.org/wiki/MOS_Technology_6502 [2] http://en.wikipedia.org/wiki/Motorola_6800
... unbelievable today, that the "operating system" resided in less than 8kB .... ;) The Basic interpreter occupied a little more than that ... so the C64 had 16kB ROM altogether.
(to be fair: The "operating system" of the C64 was not one according to today's standards, it was little more than a number of handling functions for some hardware basics ... todays BIOSes can be better compared to it)
(Then of course there's the Western Design Centre 6502 descendants, which include 16-bit extensions etc.)
Some searches led me to this [1]. The 6570-036 is the 6502-based SOC.
[1] http://deskthority.net/wiki/File:Amiga_2000_Mitsumi_controll...
d) BCD instructions, which he thinks are "kind of silly", and perhaps they are now that computers run at many GHz. But they were very useful in the old days. E.g. CBASIC [1] implemented BCD floating point math. Here's what Wiki says about it:
CBASIC proved very popular because it
incorporated 14-digit binary-coded decimal
(BCD) math which eliminated MBASIC's rounding
errors that were sometimes troublesome for
accounting.
Real numbers are stored in eight bytes of
memory. The first byte is the sign and
exponent. The exponent is maintained in
excess 64 code. The seven remaining bytes
contain a normalized mantissa stored as
packed decimal digits. The high order four
bits of the rightmost byte is the most
significant digit of the mantissa.
When a CPU runs at 1 MHz instead of 3 GHz, doing FP in BCD means much simpler and much faster conversion between internal representation and display. A lot of early microcomputers were used by small business. BCD is inferior for complicated scientific calculations, but is ideal for simple small business accounting, which was CBASICs target market.
[1] http://en.wikipedia.org/wiki/CBASIC [2] http://www.cpm.z80.de/manuals/cbasic-m.pdf [3] http://en.wikipedia.org/wiki/IEEE_floating_point
http://retrobits.libsyn.com/show-123-an-interview-with-chuck...
At the time that the 6502 hit the computer scene in a mass-market way it wasn't like you coded your code straight into a computer. Instead you actually wrote code out on paper. Then you looked up the opcodes and typed them into a margin. That was what you typed in on many personal computers of the time. The BBC micro had assembler options that you could drop into on BBC Basic, so, if you wanted to do something really cool then assembly was an option.
This was in the pre-internet era where you might have a few books and plenty of magazines - piles of them, normally, every back issue kept. You could not Google answers and have some SO answer pop up seconds later. You would have to rifle through the indexes on the few books you had. This was not an obstacle to learning, you could actually memorise the whole instruction set and be fairly sure of what the opcodes were. So, in a way, you could be your own Google.
I had exposure to Z80 before 6502, I also had some 6809 and 68000 knowledge. However, if you were new to programming it required quite a conceptual leap to know what an index register could do. Then things like the alternate registers - what do I do with these, please? Hence, the little 6502 was nice and easy. Although there were just the three registers you could master them and do what you needed to do with just that.
To a certain extent the 6502 forced people to build a proper computer without getting the CPU to do things like drive the display (Sinclair). You didn't really have to care about system interrupts for things outside your code plus the performance was pretty good in comparison to those systems that had a Z80 'do everything'.
Although Z80 might be a bit hard as a beginner, 6502 was a bit more manageable. With concepts learned on the 6502 you could go on to the other CPUs with relative ease, e.g. 68000 was easy if you knew 6502.
Going back to the talk, I had it easy - manuals, complete computers you could buy, even dot matrix printers. Plus community in those magazines. The generation before me that actually made the stuff I picked up they were on punched cards and reel-to-reel tapes. I cannot imagine how hard it was for them or the realities of how it was to problem solve given tools available. However, I imagine that leap is similar to the leap required by this speaker to understand the little takeaway here - you could actually program the 6502 without being overwhelmed by the size of the instruction set and, through doing so, get pretty good at it.
But I agree that Theodores's post there is something wrong. Only Sinclair's ZX81/82 abuse of the Z80 to generate the screen. Zx Spectrum's had an ULA chip that handles the screen generation and other stuff, like the cassette interface.
http://blog.jgc.org/2013/04/how-i-coded-in-1985.html
(Despite the title, this was more typical of 1976 or so.) It seems awkward, but it was quite workable for embedded controllers, which was the original application that the microprocessor manufacturers had in mind.
P.S. - The Altair had a floppy option pretty much from introduction ('76 or '77, at least) as well as a cassette tape setup, so while you often bootstrapped with the front panel (unless you added a bootstrap ROM someplace; many did), you didn't have to load all your software that way. I had friends who even had paper tape readers on their Altairs, which were pretty cool.
That said, while I never wrote assembly opcodes by hand, I did know the hex values for most of the 6502 opcodes at some point. And I did later debug M68k assembler by annotating dot matrix printouts until '92 or '93 or so - I used to bring them to school with me so I could work on my compiler projects during recess.
The things you do when you don't have portable computers or network access.
True, you could program in almost any language you wanted on almost any platform. However Forth was a novelty and of the few people I knew that had Pascal, none of them actually used it - the box sat there, on the shelf. Much like today you could choose to program in Forth if you really wanted to (or Cobol) but you didn't, simple as. The 'killer apps' of the time - games - were generally written in assembler as in assembler you could do things not possible with one of your 'other languages'.
As for your quip about 68000 not being easier if you knew 6502, do you just arrogantly dismiss everything out of hand? No evidence given?
Shortly after the hey-day of things being done in assembler, I was the only person in a very large university class to get 100% for some 68000 based assembly assignment. This was my first go at 68000 and I completed my work in less than one hour. Sure 'introductory 68000' might be easy, complete 'hello world' stuff for a genius like you, however none of the hundred or so that were on that course could churn out the assignment like I could, straight off the bat. They struggled for weeks on it and most of the class cribbed answers from each other, they were that bad. The difference I had was solid 6502 experience, I took to 68000 like a duck to water, everyone else was still struggling to get their heads around what to me was a simple task.
Sure my reminiscences from aeons ago are totally anecdotal but I went on to do lots of stuff in 68000 and, without that first bit of 6502 experience, I would have struggled.
Well, 8-bit, accumulator-based, limited addressing modes, numerous quirky features required for good performance (e.g. zero page) vs. 32-bit, register-based, numerous, generally orthogonal addressing modes, privilege separation, etc. So other than 'programmed in assembly', not much similar between the two. I know when I jumped from processors like the 6502 to the 68000, I had to forget more about the 6502 to really get the 68000 than I kept. Maybe you could take your own advice and describe the architectural similarities of one processor that made you so much more prepared to understand the other? You know, give some evidence.
As to the rest of your snotty, self-indulgent, anti-American rant...it's a real shame you didn't get to play with the cool toys that existed at the time. That doesn't mean they didn't exist and we didn't use them. We'll get right on that pity party for you.
That still sounds easy, real men input code with switches, into 6809 in this example : https://www.youtube.com/watch?v=IXu8P2qGoj8
The big architectural advance was two index registers, otherwise it was really sort of a 6800 (from a programmer at the times point of view)
As mentioned above having a clock that could be created by meere mortals was a big advance (previoud chips required you to be able to drive what must have been a complete unbuffered clock tree - rail to rail voltages and high peak current.
The thing he misses about yield is that for a fixed per wafer defect rate there's a point where reducing die size to 1/4 reduces the yield fallout by almost that much
Peddle tried to sell Motorola on making a cost reduced version. When Motorola refused to let him work on a cheap version, he left to do the 65xx.
Their first model - the 6501 - was designed to be pin compatible with the 6800, and resulted in a lawsuit from Motorola that almost bankrupted MOS.