Anonymous user
Category:6800 Assembly: Difference between revisions
m
no edit summary
(Added some historic information) |
mNo edit summary |
||
Line 6:
From a programmer's standpoint, the 6800 possessed two 8-bit accumulators (A and B), two 16-bit pointer registers (X and S), and an 8-bit flag register (P). Although the 8080 had more registers and a faster base clock, real-world performance and machine-code density were quite similar, due to the more flexible addressing modes and lower clock-per-instruction ratio of the 6800. PC-relative branching instructions (with signed 8-bit displacements) and 8-bit (direct-page) addressing options also helped the 6800 in this regard. The hobbyists of the day had a tendency to fall into two different groups (the 8xxx and 6xxx 'camps'), and countless contests and debates ensued, with each group claiming that their 'family' was superior. It was quite rare to see a small-computer enthusiast in the late 1970s who didn't have a strong preference for one over the other.
The 6800 spawned many offshoots and offspring, like the MOS 65xx family, the Motorola 6809, and numerous micro-controllers. 68xx-based systems were prevalent in the late 1970s and early 1980s, in household, business, and automotive applications. Its popularity in home computers, however, was easily eclipsed by the 65xx family of microprocessors, largely due to the lower cost and comparable performance of the 65xx family. The 8080 suffered a similar fate, at the hands of the Zilog Z-80.
The Motorola 68000, designed in the late 1970s, was the popular and much more capable replacement for the 6800, and although their assembly languages both share a similarity to the DEC PDP-11 (a model of elegance and orthogonality), they are not compatible.
| |||