[A86] Re: TCP/IP stack

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[A86] Re: TCP/IP stack


> have to go to a PC to get the whole system back on the calc.  I think 
> robustness will be inportant because as soon as the OS crashes your 
> stuck  with the old OS.  What do you think?
> 
> Also the kernel would have to deal with memory fragmentation.  Like 
> in the 
> older MAC OSs when you load program A, B and C.  And then close 
> program B, 
> you have a hole in memory that is the size of program B.  Then you 
> get into 
> situations where you have lots of free ram but not enough in one 
> space to 
> load another program.  Unless you allow the kernel to rearange or 
> (defrag) 
> the memory space dynamically.  This could be made to work, but does 
> feel 
> very eligant to me.  Any thoughts?  Is this a trade-off worth 
> making?

The built-in memory system does this already, why not use it?
Then you could have a small program to boot your shiny OS from TI-OS in
case of a bad crash.

> >The TI-OS is on a 256k ROM chip. What if you replaced that, and 
> installed
> >a new 512k chip with both the TI-OS and the new OS on it? Maybe it 
> could
> >be flash. What if you could add in a second RAM chip? Giv the 
> current one
> >to the TI-OS, and add a larger one for us? Or maybe you could make 
> the
> >flash chip a couple megs, and that could be part of our virtual 
> harddisk
> >in the new OS/TIGL86 (TI-GNU/Linux 86)?

The simplest thing like this would be to add a second, identical, RAM
chip on top of the existing one.  This would bring the ram capacity up
level to the rom capacity.  Adding anything more would require you to
find extra address lines which may not even exist.  (which would mean
more complicated bank switching if it's possible at all)

> The only concern I have about this sort of solution is that it would 
> require 
> significant hardware upgrades.  This would limit the number of 
> people who 
> could make use of the system.  Purhaps it would be done in such a 

This would still be a big problem tho.  Not many people even have steady
enough hands to solder pins on a 1/20 inch spacing.

> You illuded to one idea that I've thought about, but am unsure if it 
> could 
> work or not.  That is to some how run the calculator OS from the new 
> OS by 
> making use of the the ROM.  This would require extensive knowledge 
> of how 
> code is laid out in the ROM.  This woul dbe furthur complicated by 
> differing 
> ROM versions.  But i invision a "virtual calc" application that 

I don't think different rom versions would be a problem, you just need to
know how to control the context monitor.  We already know how to call a
tios app, how to get back out, however...

You would have to play nice with TI's ram addresses on page 0, but you
should be able to restrict the tios to a small (32k?) amount of ram for
variable storage if necessary by manipulating pointers like Kirk Meyer's
ram expander, but in reverse.

> knows how to 
> run the code in the rom in such a way as to simulate the calculator 
> with 
> limited resources.  Maybe apps could be buillt for the new OS that 
> know how 
> to use the various apps of the origonal OS.  For example maybe there 

Using "pieces" of the apps in rom *would* require you to keep track of
different rom versions, and is probably more complicated than it's worth.
 My advice would be to either use the built-in code as much as possible
(otherwise you're wasting space) or rewrite what you need.  Graphing for
example could probably be made much faster if you're very clever with
your code.

-josh
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