Editing Motorola 6809 (section)

===Market acceptance===
Much of the design had been based around the market concept of building-block code. But the market for pre-rolled ROM modules never materialized: Motorola's only released example was the MC6839 floating-point ROM. The industry as a whole solved the problem of integrating code modules from separate sources by using [[Relocation (computing)|automatic relocating linkers and loaders]], which is the solution used today.<ref>{{cite book |author-last=Levine |author-first=John R. |author-link=John R. Levine |title=Linkers and Loaders |date=2000 |orig-year=October 1999 |edition=1 |publisher=[[Morgan Kaufmann]] |series=The Morgan Kaufmann Series in Software Engineering and Programming |isbn=1-55860-496-0 |chapter=Chapter 1: Linking and Loading & Chapter 3: Object Files |url=https://www.iecc.com/linker/ |access-date=2021-06-22 |archive-date=2012-12-05 |archive-url=https://archive.today/20121205032107/http://www.iecc.com/linker/ |url-status=live }}</ref> However, the decisions made by the design team enabled multi-user, multitasking operating systems like [[OS-9]] and [[UniFlex]].

The added features of the 6809 were costly; the CPU had approximately 9,000 transistors compared to the 6800's 4,100 or the 6502's 3,500. While process improvements meant it could be fabricated cheaper than the original 6800, those same improvements were being applied to the other designs and so the relative cost remained the same. Such was the case in practice; in 1981 the 6809 sold in single-unit quantities for roughly six times the price of a 6502.{{sfnb|Ancrona|1981}} For those systems that needed some of its special features, like the hardware multiplier, the system could justify its price, but in most roles, it was overlooked.

Another factor in its low use was the presence of newer designs with significantly higher performance. Among these was the [[Intel 8086]], released the same year, and its lower-cost version, the [[Intel 8088]] of 1979. A feeling for the problem can be seen in the [[Byte Sieve]] assembly language results against other designs from the era (taken from 1981<ref>{{cite magazine |title=A High-Level Language Benchmark |first=Jim |last=Gilbreath |magazine=Byte |date=September 1981 |pages=180–198 |url=https://archive.org/details/byte-magazine-1981-09/page/n181}}</ref> and 1983<ref>{{cite magazine |title=Eratosthenes Revisited: Once More through the Sieve |first1=Jim |last1=Gilbreath |first2=Gary |last2=Gilbreath |magazine=[[Byte (magazine)|BYTE]] |date=January 1983 |pages=283–325 |url=https://archive.org/details/byte-magazine-1983-01/page/n291 |volume=8 |issue=1}}
</ref>):

{| class="wikitable"
|+ Byte Sieve comparison
|-
! Processor !! Seconds !! Total clocks<br>(millions)
|-
| 6502 1&nbsp;MHz || 13.9 || 13.9
|-
| Z80 4&nbsp;MHz || 6.8 || 27.2
|-
| 6809 2&nbsp;MHz || 5.1 || 10.2 
|-
| 8086 8&nbsp;MHz || 1.9 || 15.2 
|-
| 68000 8&nbsp;MHz || 0.49 || 3.92
|}

Although the 6809 did offer a performance improvement over the likes of the 6502{{efn|Which by this time was also widely available in 2 MHz versions, as used in the [[Atari 8-bit computers]].}} and Z80, the improvement was not in line with the increase in price. For those where price was not the primary concern, but outright performance was, the new designs outperformed it by as much as an [[order of magnitude]].

Even before the 6809 was released, in 1976 Motorola had launched its own advanced CPU project, then known as Motorola Advanced Computer System on Silicon project, or MACSS. Although too late to be chosen for the [[IBM PC]] project, when MACSS appeared as the [[Motorola 68000]] in 1979 it took any remaining interest in the 6809. Motorola soon announced that their future 8-bit systems would be powered by cut-down versions of the 68000 rather than further improved versions of the 6809.