Re: TI-H: Re: ti-82 expander


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Re: TI-H: Re: ti-82 expander



Richard Piotter wrote:

> I haven't seen anything like it that's complete, but if I do, I'll get
> back to you. I do however know that there is a microcontroler based
> project underway to create a memory expander that ought to work with
> most if not all of the TI calcs with link ports. It uses standard TI
> protocol, so it doesn't even need an ASM driver. I have no idea how
> you're supposed to remember all the names of the files stored on it. An
> ASM driver can be built to read it however! I forgot the address, but if
> I find it again, I'll let you know!

I'm not exactly sure, so I'm going to arrogantly assume you're talking
about my site. ;-) Actually, in my case, I am using the LOW level TI
protocol -- I.E. the basic hardware method of sending or receiving
a byte. I do not plan to implement the HIGH level TI protocol -- I.E.
the exchange of packets using the "rules" set by TI. Thus, there will
still be an asm driver required -- Since you still need to tell the
Ex*er what to send, what calc it is connected to (so someone doesn't
try sending a TI-82 program to their TI-92 and then E-Mailing me
asking why it didn't work :-) and then you need to retreive a directory,
and do other tasks that simply are not possible without an asm driver.
What is the point then? Well, the TI protocol is implemented in 
hardware on the TI-92, and I am designing my Extender primarily for
the TI-92 (and the TI-82 and the other z80 calcs later, of course).

The hardware implementation of the TI protocol means that TI's protocol
is likely to be -=AS FAST=- as any custom protocol that anyone could
have designed. Noone that I know of has truly tested the speed of the
protocol -- Since calc to calc transfers are slower for reliability
and PC to calc transfers via the parallel port have speed bottleknecks
within the PC itself (I.E. multitasking OS, port speed itself, etc.) I'm
betting however that some pretty impresive transfer rates are availible.
Thus, using TI's protocol will give me some very nice transfer rates on
the TI-92 (not so much with the other calcs, but it won't be lower than
the calc to calc rate of that calc, at the very least) and as a bonus
I can lower development time significantly by using the ROM's own
native routines (this makes a smaller driver, too) It also makes
porting to other calcs a lot easier... since line I/O control is
not required (but it is possible on all the calcs, as far as I know.)

So basically, yes, there will still be a machine code driver but
it will be smaller, faster and less intrusive than if the Extender used
a custom protocol.

(As a side note, I have had some problems with TI-92 line I/O.. The calc
seems to freeze if you read the port directly after writing to it --
If anyone knows why this is going on, I'd appreciate a response.. I
don't personally need to deal with it :-) but I'm always interested
in learning...)

BTW, my site is at http://www.flash.net/~bryanr/extend/

Woah, that's a long message. Hope you had fun reading it all.. ;)

Regards,

Bryan Rittmeyer
bryanr@flash.net


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