21 Apr
2024
21 Apr
'24
5:16 p.m.
On 4/21/24 09:37, Mike Katz wrote:
Even the 6809 could push up to 8 registers (up to 10
bytes) at once on
one of two stacks in a single two byte instruction.
The 6809 was introduced the same year as the 8086. The 80186,
introduced in 1982, did have the "PUSHA POPA" instructions and was
considerably faster and more complex than the 8086. As far as I could
tell, the 6809 was an evolutionary dead-end, meant to fill the gap
between the very slow 6800 and the very advanced 68000; that made the
OEMs a bit uneasy, hence its limited adoption. It was also very
expensive for an 8 bit MPU--a key criterion for adoption.
--Chuck