Jump to content
decle

Pre-production version of Math Fun found

Recommended Posts

Following hard on the heels of our rundown of Vegas-II, the prototype of Las Vegas Roulette & Slots...
 

 

...we've put together an overview of what appears to be an early version of Math Fun...

 

 

 

I don't think I mention this in the video, but the bulk of Math Fun was written by Kimo Yap while he worked at APh, as you  can find out in Intellivisionaries episode 17...

 

http://intellivisionaries.com/episode-17-math-word-and-learning-fun/

 

It seems that people like Larry Zwick, who were just making small changes, were much more likely to autograph their code.  So it's easier to attribute their tweaks.


 

 

Edited by decle
Reference Kimo Yap
  • Like 12

Share this post


Link to post
Share on other sites

Love this stuff!  Hope you find more early stuff and bring this history to life!

 

I see a documentary in your future.

  • Thanks 1

Share this post


Link to post
Share on other sites
10 minutes ago, Morpheus said:

You should get the NobMattel prize for the excellent research and discoveries you make Decle!👍👍

T,FTFY.

 

Great stuff, @decle!

 

   dZ.

  • Thanks 1
  • Haha 3

Share this post


Link to post
Share on other sites

So the original Math Fun has left-to-right entry and in 1982 it was changed to right-to-left entry.  I would think the cartridges with the updated rom must be very rare; do people have Mattel cartridges with right-to-left entry?

Share this post


Link to post
Share on other sites
1 minute ago, mr_me said:

So the original Math Fun has left-to-right entry and in 1982 it was changed to right-to-left entry.  I would think the cartridges with the updated rom must be very rare; do people have Mattel cartridges with right-to-left entry?

I think I do.  I'll have to check again, but I am pretty sure.

 

I also remember only having the right-to-left entry back when I was a child.

 

    -dZ.

Share this post


Link to post
Share on other sites

Looking through the source code of Math Fun we've discovered some unknown, or at least informally documented bits and pieces.
 

Problem types:
 

As is described in the manual, there are 18 difficulty levels, broken into major colours and minor numbers (Black-1 through Red-2).  Internally these levels are numbered 0-17 and each relates to a particular problem type.  The types are defined in a table found in PROBLM.ASM (comments are mine):

 

PRBTBL:
    PTBL    SADD            ; Black-1 Single digit addition
    PTBL    SSUB            ; Black-2 Single digit subtraction
    PTBL    DADDNC          ; Black-3 Double digit addition - no carry
    PTBL    DADDC           ; Black-4 Double digit addition with carry
    PTBL    DSUBNB          ; Blue-1 Double digit subtraction no borrow
    PTBL    DSUBB           ; Blue-2 Double digit subtraction with borrow
    PTBL    TADDNC          ; Blue-3 Triple digit addition no carry
    PTBL    TADD1C          ; Blue-4 Triple digit addition one carry
    PTBL    TADD2C          ; Yellow-1 Triple digit addition two carries
    PTBL    TSUBNB          ; Yellow-2 Triple digit subtraction no borrow
    PTBL    TSUB1B          ; Yellow-3 Triple digit subtraction one borrow
    PTBL    TSUB2B          ; Yellow-4 Triple digit subtraction two borrows
    PTBL    SMULT           ; Purple-1 Single digit multiplication
    PTBL    SDIV            ; Purple-2 Single digit division
    PTBL    M1MULT          ; Purple-3 Single x multi-digit multiplication
    PTBL    DMULT           ; Purple-4 Double x double-digit multiplication    
    PTBL    D1DIV           ; Red-1 Multi by single-digit division
    PTBL    DDIV            ; Red-2 Multi by double-digit division

 

When you choose a level, you're setting the highest problem difficulty that can be used in a game.  This maximum value is stored in addresses $16f and $170 for player 1 and 2 respectively.

 

Problem difficulty adjustment:

 

I was careful to state that the maximum difficulty the player chooses was for the whole game.  There is a separate, current difficulty level which is used to generate the next problem.  This is always less than or equal to the overall game difficulty.  Its value is stored in addresses $171 and $172 for player 1 and 2.  The game can choose any problem type up to and including the current problem difficulty when setting a question.  By changing the current problem difficulty, the game can adjust the challenge for each player independently.  This is mentioned multiple times in the manual.

 

At the start of the game the next problem difficulty is set to be three less than the overall game level.  This means that the game starts slightly easier before ramping up to its ultimate challenge.  A quirk of this is that you are guaranteed to get a single-digit addition problem as the first question on all the black levels.

 

From here the current difficulty is adjusted based on the player's performance.  Get a question right and the difficulty goes up by one, limited by the overall game difficulty.  Answer incorrectly and the difficulty is dropped by two.  It is possible to drop the current difficulty down from level red-2 to level black-1 by answering nine consecutive questions incorrectly.

 

One page 1.5 (the page numbering is a bit weird in my copy), the manual suggests that the rate of progress answering puzzles may also be a factor in question difficulty...

Quote

"The computer will also automatically compensate in case one player gets too far ahead of the other"

 

...however, I've not found any evidence for this.

 

Reverse-entry is not reverse-entry, at least not all the time

 

When I made my original video about the Math Fun prototype, I included this comment from MASTER.ASM...

;*** NOTE ***    MODIFICATIONS TO INPUT ROUTINES ALLOWING RIGHT TO LEFT ENTRY
;        FOR +,-,* MADE 5/5/82 BY KJM, AFTER RESEARCH DONE BY CJH
;        A FEW WEEKS EARLIER

 

What I failed to notice at the time was that this suggests that reverse entry does not apply to division problems.  Sure enough, the comment is correct.  Forward entry is used for division problems, even in the reverse entry version of the game...

;GIVEN ADDRESS OF FLAGS IN R2, NUMBER PRESSED IN R0, PLAYER IN R1:
;SET THE FLAG TO SAY THAT A NUMBER HAS BEEN PRESSED. FIGURE THE NEW ANSWER
;BASED ON THIS NUMBER BEING USED, AND UPDATE THE ANSWER DISPLAY AND THE
;ANSWER ITSELF IF THE NEW ANSWER IS LEGAL. DIVISION IS ANSWERED LEFT TO
;RIGHT; ALL ELSE ANSWERED RIGHT TO LEFT. IF THIS IS NOT DIVISION,
;INCREMENT THE EXPONENT FOR THE CURRENT ANSWER IF THIS NUMBER IS USED.

 

This is probably evidence that the real intent of reverse-entry was to support solving problems using the step-by-step methods taught in schools.  These typically involve writing the problem down and working through it on paper.  For addition, subtraction and multiplication these techniques work from units, through tens to hundreds, but for division they work from hundreds, through tens to units.  These approaches allow students to break the question down, solving partial problems and reducing the amount of working that has to be maintained in the player's head.  This makes solving larger problems using mental arithmetic significantly easier, but makes entering answers to some of the easier problems, notably single digit multiplications like 9x7 rather unintuitive.

 

Personally, I wish we had the reverse-entry version, rather than the forward-entry variant, when we were kids as it would have made it possible to play harder levels without resorting to pen and paper.  Perhaps a better name for the reverse-entry variant is the "work-it-out" or "schools" version.  Which would make the original forward-entry version the "know-the-answer" or "mental-math-eureka" variant.

 

Blue really is the the colour

 

I was a little unconvinced by the violet ($d) colour used in the background of the prototype.  It made me suspect that this was a ROM hack put together by the Jerrold engineers.  However, there is some evidence in the production code that it was intentional.  In INIT.ASM from the production code we see the following comment...

    MOV    #UANSW1,R5        ; ** NOW IN 8 BIT RAM  -LMZ **
    MOV    R0,@R5            ;    "
    MOV    R0,@R5            ;    "
    MOV    R0,@R5            ;    "
    MOV    R0,@R5            ;    "
DOBLNK:    CALL    BLANK            ;BLANK SCREEN (LIGHT BLUE)

 

This suggests that the intention was that the colour stack was initially set to light blue ($d), also known as violet.  Then later in the code we find a commented out switch to green when setting up the game screen...

;ROUTINE TO SET UP SCREEN

SCRNSET:
;**    MOV    #CH.GREEN,R1
;**    MOV    R1,.BCOLTAB        ;CHANGE BACKGROUND STACK BACK
    CALL    BLANK            ;FILL THE SCREEN WITH BLANKS

 

So, it looks as though the original intention was to have a light blue background for the selection screen, but then green for the game.  However, our prototype originates from a period where the switch to green was commented out, but before the colour stack entries in the cartridge headers were changed.  Leaving it with a light blue background throughout.

 

Cut the music already

 

We can see that someone really didn't like the Electric Company theme tune.  In addition to the second half being cut, Larry Zwick added the following code during game setup:

    MOV    R1,.KEYDSP
    CLR    R5            ; ** AND LAST, TURN OFF THEME MUSIC
    MOV    R5,.SPRIO        ; **  -LMZ **

 

This isn't present in the prototype, and as a consequence the tune plays to completion, even if you get through the selection quickly and onto the game screen.  In the production release it is cut short once the Gorillas come into view.

 

Animal switcheroo

 

There seems to have been a change in the animals setting the questions at some point during development.  In the code, the antelope is labelled a horse, and the kangaroo is named cat2.  What I have always thought is a sheep is identified as a zebra, and seems to have been added as a bit of an afterthought, as it is not defined with the rest of the zoo.  On page 2 of the manual there is something that looks suspiciously like a camel, which does not appear in the game at all.  This creature also appears in the mock-up (notice the probable violation of the 2 colour rule) shown in all the game catalogues...

 

image.png.c030700eb498311a756d1ece1178d259.png

 

Although the graphics are the same, the colours of a number of the animals were also changed between the prototype and the final release.

 

On 10/9/2021 at 8:14 PM, mr_me said:

I would think the cartridges with the updated rom must be very rare; do people have Mattel cartridges with right-to-left entry?

I believe the easiest way to get hold of a reverse-entry cartridge is to target the white label INTV version of the game.  I don't know that they are all reverse-entry, but certainly my copy is.  It may also be a good idea to go after games in the later flip-top boxes that don't feature "The Electric Company" branding on the front...

 

image.png.b8bc22e42475db57cd2811933bcc056c.png

  • Like 5

Share this post


Link to post
Share on other sites
On 10/9/2021 at 9:14 PM, mr_me said:

So the original Math Fun has left-to-right entry and in 1982 it was changed to right-to-left entry.  I would think the cartridges with the updated rom must be very rare; do people have Mattel cartridges with right-to-left entry?

This is my "right to left" copy, how can I recognize if it's a Mattel version or not?

IMG_20211017_103204.jpg

IMG_20211017_103405.jpg

IMG_20211017_103413.jpg

Share this post


Link to post
Share on other sites
1 hour ago, MonsterSky said:

This is my "right to left" copy, how can I recognize if it's a Mattel version or not?

It says Mattel on the box.  Looks like it was made for Italy and the cartridge shell is from 1982/83.  So these cartridges were still in production later at Mattel.  

  • Like 1
  • Thanks 1

Share this post


Link to post
Share on other sites

I love you videos!  Please keep digging into these games!  Too bad you're not an Atari guy, I could use the help! :)

  • Like 1
  • Thanks 1

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...

  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...