MdntTrain

Hi, folks.

On a II+, if INTBASIC is loaded into the Language Card ram (LCr), I
know *what* the INT command does -- it switches from Applesoft in ROM
to the BASIC in the LCr .. but does anyone know exactly what steps
occur when INT is run?

At some point, INT must activate the LCr bank, which would then
immediately make Applesoft (thus presumably the rest of the INT
command code) disappear.. so I does INT set up something like a page 3
route to do the bank switch, then start intbasic at E000?

Thank you for any explanations-
-John

mmphosis

On Jan 22, 4:27*pm, MdntTrain <j...@cimmeri.com> wrote:
> Hi, folks.
>
> * On a II+, if INTBASIC is loaded into the Language Card ram (LCr), I
> know *what* the INT command does -- it switches from Applesoft in ROM
> to the BASIC in the LCr .. *but does anyone know exactly what steps
> occur when INT is run?
>
> * At some point, INT must activate the LCr bank, which would then
> immediately make Applesoft (thus presumably the rest of the INT
> command code) disappear.. so I does INT set up something like a page 3
> route to do the bank switch, then start intbasic at E000?
>
> * Thank you for any explanations-
> *-John

Beneath Apple DOS by Don Worth and Pieter Lechner
page 8 - 14

http://www.textfiles.com/apple/ANATOMY/cmdint.txt
http://www.textfiles.com/apple/ANATOMY/cmdfp.txt

Steve Nickolas

On Sun, 22 Jan 2012, MdntTrain wrote:

>
> Hi, folks.
>
> On a II+, if INTBASIC is loaded into the Language Card ram (LCr), I
> know *what* the INT command does -- it switches from Applesoft in ROM
> to the BASIC in the LCr .. but does anyone know exactly what steps
> occur when INT is run?
>
> At some point, INT must activate the LCr bank, which would then
> immediately make Applesoft (thus presumably the rest of the INT
> command code) disappear.. so I does INT set up something like a page 3
> route to do the bank switch, then start intbasic at E000?
>
> Thank you for any explanations-
> -John
>

FP and INT are part of DOS, not BASIC. And these are located in DOS
space.

A57A- A9 4C CMDFP: LDA #$4C
A57C- 20 B2 A5 JSR SETROM

A59E- A9 20 CMDINT: LDA #$20
A5A0- 20 B2 A5 JSR SETROM

Basically, there is code in the lower 48 that determines which BASIC you
want and which BASIC you're in, checks to see if the one you want is in
either ROM (C081) or RAM (C080). This works for both romcards and
ramcards. If it finds it, it will reinitialize DOS and eventually wind up
at E000.

FPBASIC has a JMP at E000, while INTBASIC has a JSR there.

The FP command also has code to load Applesoft off disk from an Integer
BASIC file called APPLESOFT, if necessary.

-uso.

D Finnigan

Steve Nickolas wrote:
> On Sun, 22 Jan 2012, MdntTrain wrote:
>
>>
>> Hi, folks.
>>
>> On a II+, if INTBASIC is loaded into the Language Card ram (LCr), I
>> know *what* the INT command does -- it switches from Applesoft in ROM
>> to the BASIC in the LCr .. but does anyone know exactly what steps
>> occur when INT is run?
>>
>> At some point, INT must activate the LCr bank, which would then
>> immediately make Applesoft (thus presumably the rest of the INT
>> command code) disappear.. so I does INT set up something like a page 3
>> route to do the bank switch, then start intbasic at E000?
>>
>> Thank you for any explanations-
>> -John
>>
>
> FP and INT are part of DOS, not BASIC. And these are located in DOS
> space.
>

See also the DOS 3.3 User's Manual (or, Do's and Dont's of DOS).

One of the appendices has some coverage of the INT and FP commands.

--
]DF$
Mac GUI Vault - A source for retro Apple II and
Macintosh computing.
http://macgui.com/vault/

D Finnigan

D Finnigan wrote:
> Steve Nickolas wrote:
>> On Sun, 22 Jan 2012, MdntTrain wrote:
>>
>>>
>>> Hi, folks.
>>>
>>> On a II+, if INTBASIC is loaded into the Language Card ram (LCr), I
>>> know *what* the INT command does -- it switches from Applesoft in ROM
>>> to the BASIC in the LCr .. but does anyone know exactly what steps
>>> occur when INT is run?
>>>
>>> At some point, INT must activate the LCr bank, which would then
>>> immediately make Applesoft (thus presumably the rest of the INT
>>> command code) disappear.. so I does INT set up something like a page 3
>>> route to do the bank switch, then start intbasic at E000?
>>>
>>> Thank you for any explanations-
>>> -John
>>>
>>
>> FP and INT are part of DOS, not BASIC. And these are located in DOS
>> space.
>>
>
> See also the DOS 3.3 User's Manual (or, Do's and Dont's of DOS).
>
> One of the appendices has some coverage of the INT and FP commands.
>

Well, I checked the DOS 3.3 and 3.2 manuals myself last evening, and the
explanation likely isn't as technical as you would need. It describes the
search process when looking for an image of Applesoft or Integer BASIC
(either on disk or in firmware) to load, but not in great detail.