Corrections to trivia

From: Eric Smith <eric_at_brouhaha.com>
Date: Mon Oct 5 19:27:45 1998

Doug Yowza <yowza_at_yowza.com> wrote:
> I thought the F8 was two-chip (ALU and control logic on two different
> chips). Mostek made a microprocessor version of the F8 (3840?).

No, the entire F8 CPU was on a single chip. I'm not sure about a Fairchild
part number; Mostek second-sourced it with the part number MK3850.

The confusion may stem from an unusual feature of the F8 bus. Each F8
support chip maintained a local copy of the program counter and data pointer,
in order to reduce the necessary bus bandwidth. However, the CPU was
complete in that it contained the master copy of both pointers. Note that
the HP Saturn processor used in the HP-71B handheld computer in 1984,
and in all HP handheld calculators since 1986, uses the same principle.

Mostek also made single-chip-microcontroller variants in the MK3870 series.

> My definition is ALU and control logic on a single chip.

Seems basically reasonable, although "control logic" is a bit vague. Your
definition could apply to hardwired processors that do not execute stored
programs.

Eric
Received on Mon Oct 05 1998 - 19:27:45 BST