Re: Stealing a Great Idea from the 6600

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Sujet : Re: Stealing a Great Idea from the 6600
De : quadibloc (at) *nospam* servername.invalid (John Savard)
Groupes : comp.arch
Date : 22. Apr 2024, 23:22:11
Autres entêtes
Organisation : A noiseless patient Spider
Message-ID : <hmod2jpvun417k1qjm04pvro5gvt3u21rg@4ax.com>
References : 1 2 3 4 5 6 7 8 9 10
User-Agent : Forte Free Agent 3.3/32.846
On Mon, 22 Apr 2024 14:13:41 -0600, John Savard
<quadibloc@servername.invalid> wrote:

On Sat, 20 Apr 2024 17:07:11 +0000, mitchalsup@aol.com (MitchAlsup1)
wrote:
John Savard wrote:
>
And, hey, I'm not the first guy to get sunk because of forgetting what
lies under the tip of the iceberg that's above the water.
>
That also happened to the captain of the _Titanic_.
>
Concer-tina-tanic !?!
>
Oh, dear. This discussion has inspired me to rework the basic design
of Concertina II _yet again_!
>
The new design, not yet online, will have the following features:
>
The code stream will continue to be divided into 256-bit blocks.
>
However, block headers wil be eliminated. Instead, this functionality
will be subsumed into the instruction set.
>
Case I:
>
Indicating that from 1 to 7 32-bit instruction slots in a block are
not used for instructions, but instead may contain pseudo-immediates
will be achieved by:
>
Placing a two-address register-to-register operate instruction in the
first instruction slot in a block. These instructions will have a
three-bit field which, if nonzero, indicates the amount of space
reserved.
>
To avoid waste, when such an instruction is present in any slot other
than the first, that field will have the following function:
>
If nonzero, it points to an instruction slot (slots 1 through 7, in
the second through eighth positions) and a duplicate copy of the
instruction in that slot will be placed in the instruction stream
immediately following the instruction with that field.
>
The following special conditions apply:
>
If the instruction slot contains a pair of 16-bit instructions, only
the first of those instructions is so inserted for execution.
>
The instruction slot may not be one that is reserved for
pseudo-immediates, except that it may be the _first_ such slot, in
which case, the first 16 bits of that slot are taken as a 16-bit
instruction, with the format indicated by the first bit (as opposed to
the usual 17th bit) of that instruction slot's contents.
>
So it's possible to reserve an odd multiple of 16 bits for
pseudo-immediates, so as to avoid waste.
>
Case II:
>
Instructions longer than 32 bits are specified by being of the form:
>
The first instruction slot:
>
11111
00
(3 bits) length in instruction slots, from 2 to 7
(22 bits) rest of the first part of the instruction
>
All remaining instruction slots:
>
11111
(3 bits) position within instruction, from 2 to 7
(24 bits) rest of this part of the instruction
>
This mechanism, however, will _also_ be used for VLIW functionality or
prefix functionality which was formerly in block headers.
>
In that case, the first instruction slot, and the remaining
instruction slots, no longer need to be contiguous; instead, ordinary
32-bit instructions or pairs of 16-bit instlructions can occur between
the portions of the ensemble of prefixed instructions formed by this
means.
>
And there is a third improvement.
>
When Case I above is in effect, the block in which space for
pseudo-immediates is reserved will be stored in an internal register
in the processor.
>
Subsequent blocks can contain operate instructions with
pseudo-immediate operands even if no space for pseudo-immediates is
reserved in those blocks. In that case, the retained copy of the last
block encountered in which pseudo-immediates were reserved shall be
referenced instead.
>
I think these changes will improve code density... or, at least, they
will make it appear that no space is obviously forced to be wasted,
even if no real improvement in code density results.

The page has now been updated to reflect this modified design.

John Savard

Date Sujet#  Auteur
17 Apr 24 * Stealing a Great Idea from the 6600128John Savard
18 Apr 24 +* Re: Stealing a Great Idea from the 6600125MitchAlsup1
18 Apr 24 i`* Re: Stealing a Great Idea from the 6600124John Savard
18 Apr 24 i `* Re: Stealing a Great Idea from the 6600123MitchAlsup1
19 Apr 24 i  `* Re: Stealing a Great Idea from the 6600122John Savard
19 Apr 24 i   `* Re: Stealing a Great Idea from the 6600121John Savard
19 Apr 24 i    `* Re: Stealing a Great Idea from the 6600120MitchAlsup1
20 Apr 24 i     +* Re: Stealing a Great Idea from the 66002John Savard
21 Apr 24 i     i`- Re: Stealing a Great Idea from the 66001John Savard
20 Apr 24 i     `* Re: Stealing a Great Idea from the 6600117John Savard
20 Apr 24 i      `* Re: Stealing a Great Idea from the 6600116John Savard
20 Apr 24 i       `* Re: Stealing a Great Idea from the 6600115MitchAlsup1
20 Apr 24 i        +* Re: Stealing a Great Idea from the 6600105BGB
21 Apr 24 i        i`* Re: Stealing a Great Idea from the 6600104MitchAlsup1
21 Apr 24 i        i +* Re: Stealing a Great Idea from the 660063John Savard
21 Apr 24 i        i i+* Re: Stealing a Great Idea from the 660015John Savard
25 Apr 24 i        i ii`* Re: Stealing a Great Idea from the 660014Lawrence D'Oliveiro
25 Apr 24 i        i ii +* Re: Stealing a Great Idea from the 660012MitchAlsup1
25 Apr 24 i        i ii i+- Re: Stealing a Great Idea from the 66001Lawrence D'Oliveiro
30 Apr 24 i        i ii i`* Re: a bit of history, Stealing a Great Idea from the 660010John Levine
3 May 24 i        i ii i `* Re: a bit of history, Stealing a Great Idea from the 66009Anton Ertl
3 May 24 i        i ii i  +* Re: a bit of history, Stealing a Great Idea from the 66007John Levine
4 May 24 i        i ii i  i`* Re: a bit of history, Stealing a Great Idea from the 66006Thomas Koenig
4 May 24 i        i ii i  i +* Re: a bit of history, Stealing a Great Idea from the 66004John Levine
4 May 24 i        i ii i  i i`* Re: a bit of history, Stealing a Great Idea from the 66003MitchAlsup1
5 May 24 i        i ii i  i i `* Re: a bit of history, Stealing a Great Idea from the 66002Thomas Koenig
5 May 24 i        i ii i  i i  `- Re: a bit of history, Stealing a Great Idea from the 66001MitchAlsup1
28 Jul 24 i        i ii i  i `- Re: a bit of history, Stealing a Great Idea from the 66001Lawrence D'Oliveiro
3 May 24 i        i ii i  `- Re: a bit of history, Stealing a Great Idea from the 66001MitchAlsup1
25 Apr 24 i        i ii `- Re: Stealing a Great Idea from the 66001John Savard
21 Apr 24 i        i i`* Re: Stealing a Great Idea from the 660047MitchAlsup1
23 Apr 24 i        i i +* Re: Stealing a Great Idea from the 660045George Neuner
23 Apr 24 i        i i i`* Re: Stealing a Great Idea from the 660044MitchAlsup1
25 Apr 24 i        i i i `* Re: Stealing a Great Idea from the 660043George Neuner
26 Apr 24 i        i i i  `* Re: Stealing a Great Idea from the 660042BGB
26 Apr 24 i        i i i   `* Re: Stealing a Great Idea from the 660041MitchAlsup1
26 Apr 24 i        i i i    +* Re: Stealing a Great Idea from the 66002Anton Ertl
26 Apr 24 i        i i i    i`- Re: Stealing a Great Idea from the 66001MitchAlsup1
26 Apr 24 i        i i i    +* Re: Stealing a Great Idea from the 66004BGB
26 Apr 24 i        i i i    i+* Re: Stealing a Great Idea from the 66002MitchAlsup1
27 Apr 24 i        i i i    ii`- Re: Stealing a Great Idea from the 66001BGB
26 Apr 24 i        i i i    i`- Re: Stealing a Great Idea from the 66001MitchAlsup1
27 Apr 24 i        i i i    `* Re: Stealing a Great Idea from the 660034BGB
27 Apr 24 i        i i i     `* Re: Stealing a Great Idea from the 660033MitchAlsup1
28 Apr 24 i        i i i      `* Re: Stealing a Great Idea from the 660032BGB
28 Apr 24 i        i i i       `* Re: Stealing a Great Idea from the 660031MitchAlsup1
28 Apr 24 i        i i i        `* Re: Stealing a Great Idea from the 660030BGB
28 Apr 24 i        i i i         +* Re: Stealing a Great Idea from the 660024BGB
28 Apr 24 i        i i i         i`* Re: Stealing a Great Idea from the 660023BGB
28 Apr 24 i        i i i         i `* Re: Stealing a Great Idea from the 660022Thomas Koenig
28 Apr 24 i        i i i         i  `* Re: Stealing a Great Idea from the 660021BGB
28 Apr 24 i        i i i         i   `* Re: Stealing a Great Idea from the 660020BGB
28 Apr 24 i        i i i         i    +* Re: Stealing a Great Idea from the 66002Thomas Koenig
28 Apr 24 i        i i i         i    i`- Re: Stealing a Great Idea from the 66001BGB
29 Jul 24 i        i i i         i    +* Re: Stealing a Great Idea from the 660016Lawrence D'Oliveiro
29 Jul 24 i        i i i         i    i+* Re: Stealing a Great Idea from the 66006BGB
30 Jul 24 i        i i i         i    ii`* Re: Stealing a Great Idea from the 66005Lawrence D'Oliveiro
30 Jul 24 i        i i i         i    ii `* Re: Stealing a Great Idea from the 66004BGB
31 Jul 24 i        i i i         i    ii  `* Re: Stealing a Great Idea from the 66003Lawrence D'Oliveiro
31 Jul 24 i        i i i         i    ii   `* Re: Stealing a Great Idea from the 66002BGB
1 Aug 24 i        i i i         i    ii    `- Re: Stealing a Great Idea from the 66001Lawrence D'Oliveiro
29 Jul 24 i        i i i         i    i`* Re: Stealing a Great Idea from the 66009Terje Mathisen
29 Jul 24 i        i i i         i    i `* Re: Stealing a Great Idea from the 66008MitchAlsup1
30 Jul 24 i        i i i         i    i  +- Re: Stealing a Great Idea from the 66001Lawrence D'Oliveiro
30 Jul 24 i        i i i         i    i  +* Re: Stealing a Great Idea from the 66004Michael S
30 Jul 24 i        i i i         i    i  i`* Re: Stealing a Great Idea from the 66003MitchAlsup1
31 Jul 24 i        i i i         i    i  i `* Re: Stealing a Great Idea from the 66002BGB
1 Aug 24 i        i i i         i    i  i  `- Re: Stealing a Great Idea from the 66001Lawrence D'Oliveiro
1 Aug 24 i        i i i         i    i  `* Re: Stealing a Great Idea from the 66002Thomas Koenig
1 Aug 24 i        i i i         i    i   `- Re: Stealing a Great Idea from the 66001MitchAlsup1
29 Jul 24 i        i i i         i    `- Re: Stealing a Great Idea from the 66001George Neuner
28 Apr 24 i        i i i         `* Re: Stealing a Great Idea from the 66005MitchAlsup1
28 Apr 24 i        i i i          `* Re: Stealing a Great Idea from the 66004BGB
29 Apr 24 i        i i i           `* Re: Stealing a Great Idea from the 66003MitchAlsup1
29 Apr 24 i        i i i            `* Re: Stealing a Great Idea from the 66002BGB
29 Apr 24 i        i i i             `- Re: Stealing a Great Idea from the 66001Thomas Koenig
29 Apr 24 i        i i `- Re: Stealing a Great Idea from the 66001Tim Rentsch
21 Apr 24 i        i `* Re: Stealing a Great Idea from the 660040BGB
21 Apr 24 i        i  `* Re: Stealing a Great Idea from the 660039MitchAlsup1
22 Apr 24 i        i   +* Re: Stealing a Great Idea from the 66003BGB
22 Apr 24 i        i   i`* Re: Stealing a Great Idea from the 66002MitchAlsup1
22 Apr 24 i        i   i `- Re: Stealing a Great Idea from the 66001BGB
22 Apr 24 i        i   +* Re: Stealing a Great Idea from the 66002John Savard
22 Apr 24 i        i   i`- Re: Stealing a Great Idea from the 66001BGB
22 Apr 24 i        i   `* Re: Stealing a Great Idea from the 660033Terje Mathisen
22 Apr 24 i        i    +- Re: Stealing a Great Idea from the 66001BGB
13 Jun 24 i        i    `* Re: Stealing a Great Idea from the 660031Kent Dickey
13 Jun 24 i        i     +* Re: Stealing a Great Idea from the 660016Stefan Monnier
13 Jun 24 i        i     i`* Re: Stealing a Great Idea from the 660015BGB
13 Jun 24 i        i     i `* Re: Stealing a Great Idea from the 660014MitchAlsup1
14 Jun 24 i        i     i  `* Re: Stealing a Great Idea from the 660013BGB
18 Jun 24 i        i     i   `* Re: Stealing a Great Idea from the 660012MitchAlsup1
19 Jun 24 i        i     i    +* Re: Stealing a Great Idea from the 66008BGB
19 Jun 24 i        i     i    i`* Re: Stealing a Great Idea from the 66007MitchAlsup1
19 Jun 24 i        i     i    i +* Re: Stealing a Great Idea from the 66005BGB
19 Jun 24 i        i     i    i i`* Re: Stealing a Great Idea from the 66004MitchAlsup1
20 Jun 24 i        i     i    i i `* Re: Stealing a Great Idea from the 66003Thomas Koenig
20 Jun 24 i        i     i    i i  `* Re: Stealing a Great Idea from the 66002MitchAlsup1
21 Jun 24 i        i     i    i i   `- Re: Stealing a Great Idea from the 66001Thomas Koenig
20 Jun 24 i        i     i    i `- Re: Stealing a Great Idea from the 66001John Savard
19 Jun 24 i        i     i    +- Re: Stealing a Great Idea from the 66001Thomas Koenig
20 Jun 24 i        i     i    +- Re: Stealing a Great Idea from the 66001MitchAlsup1
31 Jul 24 i        i     i    `- Re: Stealing a Great Idea from the 66001Lawrence D'Oliveiro
13 Jun 24 i        i     +* Re: Stealing a Great Idea from the 660013MitchAlsup1
14 Jun 24 i        i     `- Re: Stealing a Great Idea from the 66001Terje Mathisen
22 Apr 24 i        `* Re: Stealing a Great Idea from the 66009John Savard
18 Apr 24 `* Re: Stealing a Great Idea from the 66002Lawrence D'Oliveiro

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