On Wed, Jan 18, 2017 at 10:47 AM, Peter Jeremy <peter@rulingia.com> wrote:

On 2017-Jan-18 07:04:31 +0100, Lars Brinkhoff <lars@nocrew.org> wrote:
>The PDP-10 did not have a fixed byte size. Were there any 9-bit
>machines?

The Honeywell 6000 series (aka 66/DPS, a rebadged GE 6xx series) was
36-bit and supported either 6-bit or 9-bit characters. I don't recall
how you selected which you were using but I recall both Pascal and APL
used the 9-bit byte.

The [EIS] instruction set supported 4, 6 and 9 bit operands; it was a matter of which instructions you used.

For pl1, the instructions generated were driven by the DCLs; for Pascal and APL, [I would guess] that the compiler/interpreter writers defined character size to be 9 bits and generated the 9 bit variants of the instructions.

Move 9 6-bit bytes starting at the 3rd byte in the word, convert to 4 bit bytes in some signed manner, and store as 10 4-bit bytes starting at offset 6.

MLR ,,400 move with sign captured
ADSC6 FLD1,3,9 sending descriptor
ADSC4 FLD2,6,10 receiving descriptor

-- Charles