PDP-11 Chess VI (Belle) By Ken Thompson (1973) ported

[JohnW]

This is cool. I just had it play the Cray Blitz 49H uci

[gepasi]

Thank you! It is is great to be able to run this oldie. However, in testing it with Cutechess it revealed that it is not doing pawn promotion right. In this position
[d]r1b2rk1/1p1B1pp1/2p5/8/2P1Pp2/8/pK5P/3R3R b - - 1 22
it played:

Code: Select all

<PDP11 Chess VI(6): move a2a1
>PDP11 Chess VI(6): force
>PDP11 Chess VI(6): result 1-0 {Black makes an illegal move: a2a1}
>PDP11 Chess VI(6): ping 20

so Cutechess adjudicated the game to white...

[Ajedrecista]

Hello:

Probably needs to specify the piece to promote? For example a2a1Q (uppercase or lowecase). Plus decide with or without and equal sign and check. Going lowecase, without check/checkmate and without equal sign: a2a1q, a2a1r, a2a1b or a2a1n. I hope a fix is possible.

Regards from Spain.

Ajedrecista.

[Jim Ablett]

Hello:

Probably needs to specify the piece to promote? For example a2a1Q (uppercase or lowecase). Plus decide with or without and equal sign and check. Going lowecase, without check/checkmate and without equal sign: a2a1q, a2a1r, a2a1b or a2a1n. I hope a fix is possible.

Regards from Spain.

Ajedrecista.

Thanks for bug report. I will post update soon.

Jim.

[Tibono]

Hi,
by the way, if you could have a look to the book bug in console mode... this would be great. Thanks!

...In console mode, only 'book off' option works (Windows version)...

[Jim Ablett]

Hi,
by the way, if you could have a look to the book bug in console mode... this would be great. Thanks!

...In console mode, only 'book off' option works (Windows version)...

I don't see that:

PDP-11 Chess Engine
Search depth: 8
Opening book: ON

Book file: book.dat (134 bytes)
Opening book loaded successfully
Thinking time set to 10 secs (default)
mfmt
Algebraic notation ON
book
Opening book OFF
first
Thinking for up to 10 seconds...

Thinking for 10 seconds... d1/+0 d2/+80 d3/+0 d4/+0 d5/+0 d6/+30 d7/+0
d7 in 9.0s (target: 10s)
Computer plays: g1f3
1. g1f3

Jim.

[Tibono]

Hi Jim,
the case you are showing is running in console mode with book off.
Indeed the Belle program thinks to depth 7 in 9 secs to play 1.Nf3 - that is consistent. The game can go on.

The issue is doing the same with book on.

Code: Select all

PDP-11 Chess Engine
  Search depth: 8
  Opening book: ON

Book file: book.dat (274 bytes)
Opening book loaded successfully
Thinking time set to 10 secs (default)
mfmt
Algebraic notation ON
first
Computer plays: e2e4
1. e2e4

8  R N B Q K B N R
7  P P P P P P P P
6  - * - * - * - *
5  - * - * - * - *
4  - * - * - * - *
3  - * - * - * - *
2  p p p p p p p p
1  r n b q k b n r

   a b c d e f g h   [Algebraic format: ON]

After 1.e2e4 announced, Enter was pressed to display the resulting position. Computer move has NOT been recorded and the game cannot proceed normally. Just try playing a game with book on, it just doesn't work.
Eric

[Jim Ablett]

Hi Jim,
the case you are showing is running in console mode with book off.
Indeed the Belle program thinks to depth 7 in 9 secs to play 1.Nf3 - that is consistent. The game can go on.

The issue is doing the same with book on.

Code: Select all

PDP-11 Chess Engine
  Search depth: 8
  Opening book: ON

Book file: book.dat (274 bytes)
Opening book loaded successfully
Thinking time set to 10 secs (default)
mfmt
Algebraic notation ON
first
Computer plays: e2e4
1. e2e4

8  R N B Q K B N R
7  P P P P P P P P
6  - * - * - * - *
5  - * - * - * - *
4  - * - * - * - *
3  - * - * - * - *
2  p p p p p p p p
1  r n b q k b n r

   a b c d e f g h   [Algebraic format: ON]

After 1.e2e4 announced, Enter was pressed to display the resulting position. Computer move has NOT been recorded and the game cannot proceed normally. Just try playing a game with book on, it just doesn't work.
Eric

Look like board display is not being updated between moves but engine is playing game correctly. In your sequence if you type next move for you e7e5 then computer will reply with it's next move >

PDP-11 Chess Engine
Search depth: 8
Opening book: ON

Book file: book.dat (134 bytes)
Opening book loaded successfully
Thinking time set to 10 secs (default)
mfmt
Algebraic notation ON
first
Computer plays: e2e4
1. e2e4

8 R N B Q K B N R
7 P P P P P P P P
6 - * - * - * - *
5 - * - * - * - *
4 - * - * - * - *
3 - * - * - * - *
2 p p p p p p p p
1 r n b q k b n r

a b c d e f g h [Algebraic format: ON]
e7e5
1. ... e7e5
Computer plays: g1f3
2. g1f3

8 R N B Q K B N R
7 P P P P P P P P
6 - * - * - * - *
5 - * - * - * - *
4 - * - * - * - *
3 - * - * - * - *
2 p p p p p p p p
1 r n b q k b n r

a b c d e f g h [Algebraic format: ON]

Jim.

[Tibono]

Here are some games, Jim...

A short one PDP11 playing as Black

Code: Select all

PDP-11 Chess Engine
  Search depth: 8
  Opening book: ON

Book file: book.dat (274 bytes)
Opening book loaded successfully
Thinking time set to 10 secs (default)
mfmt
Algebraic notation ON
e2e4
1. e2e4
Computer plays: g8f6
1. ... g8f6
e4e5
Illegal move

PDP11 playing as White:

Code: Select all

PDP-11 Chess Engine
  Search depth: 8
  Opening book: ON

Book file: book.dat (274 bytes)
Opening book loaded successfully
Thinking time set to 10 secs (default)
mfmt
Algebraic notation ON
first
Computer plays: e2e4
1. e2e4
e7e5
1. ... e7e5
Computer plays: g1f3
2. g1f3
b8c6
2. ... b8c6
Computer plays: c2c3
3. c2c3
d7d5
3. ... d7d5
Computer plays: d2d3
4. d2d3
g8f6
4. ... g8f6
Computer plays: a2a4
5. a2a4
d5e4
Illegal move

Another one going beyond the book:

Code: Select all

PDP-11 Chess Engine
  Search depth: 8
  Opening book: ON

Book file: book.dat (274 bytes)
Opening book loaded successfully
Thinking time set to 10 secs (default)
mfmt
Algebraic notation ON
first
Computer plays: e2e4
1. e2e4
c7c5
1. ... c7c5
Computer plays: g1f3
2. g1f3
d7d6
2. ... d7d6
Computer plays: c2c3
3. c2c3
g8f6
3. ... g8f6
Computer plays: d2d3
4. d2d3
g7g6
4. ... g7g6
Computer plays: a2a4
5. a2a4
h7h6
5. ... h7h6
Computer plays: h2h3
6. h2h3
b8c6
6. ... b8c6
Thinking for up to 10 seconds...

  Thinking for 10 seconds... d1/+0 d2/+80 d3/+0 d4/+0 d5/+0 d6/+30 d7/+0
  d7 in 9.0s (target: 10s)
Computer plays: b1c3
7. b1c3

c3 square is occupied since its own move 3. c2c3

Moves are not recorded onto the position. Please trust me.
All the best,
Eric

[Jim Ablett]

Here are some games, Jim...

A short one PDP11 playing as Black

Code: Select all

PDP-11 Chess Engine
  Search depth: 8
  Opening book: ON

Book file: book.dat (274 bytes)
Opening book loaded successfully
Thinking time set to 10 secs (default)
mfmt
Algebraic notation ON
e2e4
1. e2e4
Computer plays: g8f6
1. ... g8f6
e4e5
Illegal move

PDP11 playing as White:

Code: Select all

PDP-11 Chess Engine
  Search depth: 8
  Opening book: ON

Book file: book.dat (274 bytes)
Opening book loaded successfully
Thinking time set to 10 secs (default)
mfmt
Algebraic notation ON
first
Computer plays: e2e4
1. e2e4
e7e5
1. ... e7e5
Computer plays: g1f3
2. g1f3
b8c6
2. ... b8c6
Computer plays: c2c3
3. c2c3
d7d5
3. ... d7d5
Computer plays: d2d3
4. d2d3
g8f6
4. ... g8f6
Computer plays: a2a4
5. a2a4
d5e4
Illegal move

Another one going beyond the book:

Code: Select all

PDP-11 Chess Engine
  Search depth: 8
  Opening book: ON

Book file: book.dat (274 bytes)
Opening book loaded successfully
Thinking time set to 10 secs (default)
mfmt
Algebraic notation ON
first
Computer plays: e2e4
1. e2e4
c7c5
1. ... c7c5
Computer plays: g1f3
2. g1f3
d7d6
2. ... d7d6
Computer plays: c2c3
3. c2c3
g8f6
3. ... g8f6
Computer plays: d2d3
4. d2d3
g7g6
4. ... g7g6
Computer plays: a2a4
5. a2a4
h7h6
5. ... h7h6
Computer plays: h2h3
6. h2h3
b8c6
6. ... b8c6
Thinking for up to 10 seconds...

  Thinking for 10 seconds... d1/+0 d2/+80 d3/+0 d4/+0 d5/+0 d6/+30 d7/+0
  d7 in 9.0s (target: 10s)
Computer plays: b1c3
7. b1c3

c3 square is occupied since its own move 3. c2c3

Moves are not recorded onto the position. Please trust me.
All the best,
Eric

Ok, thanks for that. I see now. I will fix this.

Cheers,
Jim.