Re: A92: Update on Fargo / 92+
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Re: A92: Update on Fargo / 92+
David Ellsworth wrote:
> I received my 92 Plus module yesterday (the 29th).
>
> Here are some highlights of what I have found.
>
> ROM layout
> ----------
> * The first 64k sector of ROM is locked. It is used during boot only. If
> the ROM has been corrupted somehow, the boot section will allow you to
> restore it from a computer.
> * Following that is 8k of what seems to be either uninitialized data, or an
> I/O area for Flash ROM access.
> * That leaves us at the address $412000. That is the start of rewritable ROM.
>
> ASM file format
> ---------------
> Rusty Wagner's description of the format is correct, except that there is a
> relocation table in between the ASM program and the 0xF3 signature. It
> starts at the highest address and goes backwards, as follows:
>
> lowest address: terminating marker 0x0000 (word)
> destination offset (word) \ relocation
> referencing offset (word) / entry #n
> destination offset (word) \ relocation
> referencing offset (word) / entry #n-1
> ......
> destination offset (word) \ relocation
> referencing offset (word) / entry #2
> destination offset (word) \ relocation
> highest address: referencing offset (word) / entry #1
>
> As you can see, it is very inefficient; each entry takes up 4 bytes. The
> high-addressed word in an entry is the "referencing offset" -- it points to
> the longword that needs to be relocated. The low-addressed in an entry is
> the "destination offset", the offset that the longword being relocated is
> supposed to point at. Offsets are relative to the base address of the ASM
> code.
>
> Progress with Fargo
> -------------------
> * Modified Linux flink to work with the TI-92 Plus.
> * Modified flinker, adding an option to create a Plus ASM program.
> In the process I unearthed a bug in flinker and fixed it. This may
> have been the bug that was causing the DOS version of flinker to
> crash and/or generate corrupted files!
>
> Plans
> -----
> - Adapt flinker, adding an option to generate a Plus ASM Fargo kernel
> installer.
> - Adapt the Fargo kernel to work on the TI-92 Plus.
> - Implement of the following compatibility solutions:
> 1) Write a compatibility module allowing older Fargo II programs to be
> run on the new Plus-compatible Fargo.
> 2) Write a computer program to convert older Fargo II programs to work
> under the new Plus-compatible Fargo.
> 3) Both of the above.
>
> ---
> David Ellsworth
> davidell@earthling.net
> IRC: eXocomp
> ICQ: 2300673
What about the ability to run _very old_ Fargo 0.1.x programs on the new
Plus-compatible Fargo?
--
Bryan Rabeler <brabeler@ticalc.org>
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