Re: Announcing: Apple II Plus ROM Board

["Michael J. Mahon" <mjmahon@aol.com>]

History Student wrote:
> "William Garber" <willy46pa@garberstreet.com> wrote in message 
> CL-dnYzd3NUqPS7YnZ2dnUVZ_oqmnZ2d@comcast.com">news:CL-dnYzd3NUqPS7YnZ2dnUVZ_oqmnZ2d@comcast.com...
>
> > <bieling@terra.es> wrote in message 
> > 1169398140.795160.147350@38g2000cwa.googlegroups.com">news:1169398140.795160.147350@38g2000cwa.googlegroups.com..
>
>
> > : What for would you need to have different
> > : keyboard mappings ?
> >
> > The keyboard of the II+ is mapped in the encoder
> > on the keyboard itself, and the character map is
> > defined in the CharGen ROM to the left of the
> > keyboard connector on the motherboard. To change
> > the character map you need to convert that socket
> > to 2716 and have a dual adapter with a 2732 or
> > two 2716's onboard.
>
>
> This "KeyTran" device used a different encoder that was swapped with the 
> apple encoder. There was a program that could be accessed (somehow) that 
> would allow you to assign different letters to different keys, and the 
> switch on the case would allow you to switch between the different maps. I 
> honestly don't remember how it worked but the man who gave me the computer 
> thought it was the best thing since sliced bread. I'm curious about it now 
> though so I think I'm going to have to drag it back out of storage and play 
> around with it. I'm also curious about what was on the other ROM chip on the 
> switcher.
>
> I believe that Mr. Mahon has seen it, and he might be able to make an 
> educated guess at what was on the other ROM. 

("History Student", are you Ernest?!  ;-)

Very likely it was a "cracking" ROM, like the Senior PROM (or something
less elaborate), that allowed one to reset into the monitor and explore
a running program regardless of software "precautions".

The complete ROM switch that Bill has described would permit many
more interesting utilities to be placed in ROM (when Applesoft was
not needed), such as Inspector and Watson, which were a complete
disk/RAM explorer/editor in ROM.

The KeyTran device is a concept quite common on Asian Apple clone
keyboards, which often include an "alternate" key that causes the
keyboard to generate BASIC and DOS commands.  This one apparently
allows the macros to be loaded by software, so it can be customized
by the user.  I think the status LEDs above the button are a nice
touch, so you can tell which mode your keyboard is in.  ;-)

Such keyboards wouldn't require two encoders, just a new encoder
daughter board that had two external ROMs (or a bankswitched one).

The Apple ][ and ][+ both used completely self-contained keyboards
that just deliver 7-bit ASCII (plus RESET) to the main board, so it's
pretty easy to substitute another keyboard or encoder assembly to
modify its function.

-michael

NadaNet networking for Apple II computers!
Home page:  http://members.aol.com/MJMahon/

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