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pixelpedant

TI-99/4 (not 4A) ROM BASIC

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A question came up in the Zoom call today that didn't have any certain answers, and I'm wondering if anyone here has any insight. 

 

The question is: aside from having a different cursor, are there any functional differences between the BASIC contained in ROM on the TI-99/4 and the BASIC contained in ROM on the TI-99/4A?

 

 

 

 

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I WOULD LOVE TO GET A COPY OF VERSION 100 OF EXTENDED BASIC ROMS AND GROMS.

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Posted (edited)
50 minutes ago, RXB said:

I WOULD LOVE TO GET A COPY OF VERSION 100 OF EXTENDED BASIC ROMS AND GROMS.

Not the subject being discussed.

We are talking about the BASIC built into the ROM of the TI-99/4, not XB 1.0

 

I've played around just a bit with the TI-99/4 in emulation, and aside from certain key strokes being different, could not tell much of a difference.

The TI-99/4 has a few extra bytes of RAM i believe:

(Same program used on both machines)

1 a=a+1

2 gosub 1

memory full ... print a*8

TI-99/4: 12704

TI-99/4A: 12448

Edited by jrhodes
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Going through the TI-99/4 User's Reference Guide section on BASIC, I can identify no fundamental differences myself.  And it sure does seem that early BASIC programs which assert modifications are necessary for use on TI-99/4 are just about non-existent.   It seems like there was a widespread assumption of intercompatibility of BASIC programs. 

 

But that does not necessitate that there are no changes "under the hood". And the availability of 256 bytes of additional RAM to BASIC on the TI-99/4 certainly seems suspicious. 

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4 hours ago, RXB said:

I WOULD LOVE TO GET A COPY OF VERSION 100 OF EXTENDED BASIC ROMS AND GROMS.

unzip exbasic1.zip

 

(MAME ROM package of Extended Basic 100, find it on WHTech.)

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5 hours ago, pixelpedant said:

And the availability of 256 bytes of additional RAM to BASIC on the TI-99/4 certainly seems suspicious. 

IIRC, that was due to the presence of the "lower case" character set, which was absent from the 99/4. 

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4 minutes ago, Reciprocating Bill said:

IIRC, that was due to the presence of the "lower case" character set, which was absent from the 99/4. 

Of course! BASIC is a little more flexible  than XB in how it uses VDP memory. If you haven't defined any characters after 127 (or 95 for the 99/4) it uses the memory for the XB program. If you define character 128 there are 8 less bytes available. If you define 159 there are 256 less bytes available.

I glanced through the BASIC manual for the 99/4 and could see no differences other than CALL KEY.

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The only other difference I can think of is that 99/4A TI BASIC issues: * WARNING: CHECK PROGRAM IN MEMORY in the case where OLD fails, but 99/4 BASIC does not.  A brain cell way in the back part of my brain seems to think I read that somewhere that OLD on the 99/4 clears memory first, and on the 99/4A does not, but I don't remember where I read that.

 

Aren't there some bug fixes in the 99/4A TI BASIC also?  Some things with INPUT causing lock ups?

 

And I think 99/4A TI BASIC does not return a true zero for CALL KEY in some cases where the 99/4 does in certain situations.  I remember an addendum stating that after using CALL KEY(1,K,S) to check for IF S+1=1 instead of IF S = 0 or something like that.

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Extended Basic behaves differently when the 32K expansion is there or not: (note the different I/O errors, seems to be a bug)

 

I know this example well because I remember once typing in a long Basic program in the afternoon, and since my cartridge port was already unstable at that time, I decided to first OLD it before starting. (Wait, did I just type OLD??? No!!!)

 

I tried to stop loading by pressing E for end, but the program was gone:

 

0154_2x.png

0155_2x.png

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It would be interesting to see if the random number routine is the same for the 99/4 and the /4A

10 RANDOMIZE(10)

20 PRINT RND

I don't know why it would be changed, so I'm guessing it will be the same. But you never know...

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1 hour ago, senior_falcon said:

It would be interesting to see if the random number routine is the same for the 99/4 and the /4A

10 RANDOMIZE(10)

20 PRINT RND

I don't know why it would be changed, so I'm guessing it will be the same. But you never know...

It's the same according to Classic99.

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