View Full Version : Vintage Chess Player!

January 20th, 2011, 06:26 AM
I just watched this video and it was fun....


I am wondering the data entry for the chess moves is a bit bogus,
and mebe it was done cinematically that way for the "computer-unfamiliar"
general public of the time :wink: . What do you think?

ziloo :mrgreen:

January 20th, 2011, 08:09 AM
The move entry uses groups of 3 switches so it could be an actual quickly implemented input method. I never used 1950's era IBM big hardware so I don't know effective interactive terminal technology was back then.

I think the only move shown is the queen taking the knight. Upper set of switches has 3 switches depressed for row 8 and somewhere in the center of board with only 2 switches further to the right pressed with second row having what appears to be an attempt to enter a diagonal move forward. Well, it would work like that if upper row was starting point and lower row was ending point. Rather unusable entry system for anyone else since converting positions to binary representations is difficult to get right all the time; I had enough problems just recording chess moves back when.

January 20th, 2011, 12:49 PM
............. I had enough problems just recording chess moves back when.

Would you please elaborate......


January 20th, 2011, 08:30 PM
I don't know what sort of encoding the program author used, but the 704 (love those neon indicator lights) was a 36 bit machine (IBM didn't yet call it a computer, but rather a "calculator"). There were 4 sense switches and 36 input switches on the operator's panel. Basically the program would issue an HPR (Halt and Proceed) with the indicator lights showing the contents of the accumulator or MQ register. The move would be keyed into the panel switches and the ENTER MQ button pressed, followed by the START key and the machine would resume execution, using the data entered into the MQ register.

Mind you, this whole show was put on with only 4K words of core, with up to 16K words of drum storage (8 drums!) and finally, tape. The basic cycle time was 12 microseconds with most instructions taking at least 2 cycles to execute.

January 22nd, 2011, 06:30 AM
In front of the computer operator, Mr. Bernstein, there are
two panels: the one on the left has the register buttons and
blinking lights, and there is the left panel with 3 rows of
15 sets of buttons/lights (four on each set) and one row of
15 knobs (?) on the bottom. Based on the descriptions
about IBM 704 on wiki, it says that 704 has three sets of
15 bit registers.

What do theses buttons/lights/knobs do?


January 22nd, 2011, 09:34 AM
Not so--the 704 was a 36-bit machine, like many of its successors, like the 7090. There's plenty of documentation on the 704 at bitsavers.

January 22nd, 2011, 11:07 AM
What I meant was that are there any one-to-one correspondence
between these 15 sets of buttons and the bit locations within the


January 22nd, 2011, 11:24 AM
It's not clear that the unit with knobs and buttons (I don't know what it is; it's not part of the standard 704 configuration) has anything to do with the chess program. It's not mentioned in the WJCC paper.

January 22nd, 2011, 12:03 PM
Thank you Chuck! You have been right as always!

The 704 used a 36-bit word length; the basic instruction
format was a 3-bit prefix, 15-bit decrement, 3-bit tag,
and 15-bit address. The three bits of the tag specified
three index registers, the contents of which were
subtracted from the address to produce an effective address.

And a big thanks to krebizfan as well! There are a whole lot of
video footage about mainframe computers on the net...