Extra chip on M8186

From: Allison J Parent <allisonp_at_world.std.com>
Date: Tue Jul 8 10:13:17 1997

> I found a picture of another M8186 on the internet. It has one chip on
> it, the CPU (Dual chips on a single carrier). The other 3 sockets are
> blank. Mine has 2 chips. CPU BLANK BLANK CHIP. I don't have the M818
> in front of me, but does anyone know what the extra chip is for?

FRom the edge of the board in toward the middle its

MMU, spare, floatingpoint, data/control.

A minimal board will have data/control double as that's the F11 cpu. It
will only be a 16 bit address. The MMU is was nearly standard and gave
18/22 bit addressing. Floating point was in two forms FIS chip,
Floatingpoint Instruction Set which were microcode for floating point
instructions or the M8188 module that actually did floating point in
hardware (2901s!). Other options are the CIS or Commercial instruction
set (aka cobal instruction set) and there was writeable control store
if you wanted to write custom microcode for things like bitblting or

The 11/23 did not have I&D space like the later J-11 cpus.

The liniage for chip-11s is LSI11/03 (kd11-f quad width), LSI-11/2 (dual
width KD-11), LSI-11/23a (KDF-11A dual width), LSI11/23b(+) (KDF-11B quad
width), Then J-11 series.

Note while the books said the 11/23a (kdf-11a) was 18 bit I have found
many will operate as 22 bit. The KDF-11b was 22 bit addressing.

Received on Tue Jul 08 1997 - 10:13:17 BST

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