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>FFE8


senior_falcon
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Many years ago I read something about >FFE8 to >FFFF being assigned to a TI memory expansion concept mentioned in the XB ROM source that I lost.

 

It did not explain anything about it or how it worked. But it did mention a DEBUGGER CARD being used to demo the use.

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Corcomp Load Interrupt Card. I had modded it a while back to remove the 5V from the sidecarts I was dumping. LOL. Power up, go into Mini Mem, give the side car 5V, and the dump the DSR and 32K space :-)

 

If you used it as intended, and pressed the button, it would go to >FFFC and jump to that address’ contents, I believe.

 

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Millers Graphics documentation doesn't show any use for that space. I wonder if the space below the load interrupt vector was used in an older version of XB, or for some specific future function that was never implemented.

 

I use memory from >A000 up as my mailbox space in many programs. For example, my BBS software uses >a000->a500 (just over 1k) for various buffers and information passing. Since upper memory usage is determined by program size plus numeric variable run-time space, it is relatively easy to ensure my program 'modules' never cross into that area.

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According to Thierry: "As mentionned above, the five registers of the floppy disk controller map in the memory area >FFF0-FFFF. The addresses are different for read operations than for write operations".

That must be a misprint. The assembly code examples on that page all show the registers stored at >5FF0 to >5FFF. Which makes sense because the disk system will work without memory expansion.

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According to Thierry: "As mentionned above, the five registers of the floppy disk controller map in the memory area >FFF0-FFFF. The addresses are different for read operations than for write operations".

 

I always wondered why TI Forth (and fbForth by inheritance) stayed clear of >FFF2 – >FFFF. The 82-byte Terminal Input Buffer (>FFA0 – >FFF1) is the highest memory used. Perhaps this is the reason—or not (per Harry's post above).

 

...lee

 

[Edits in this color.]

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That must be a misprint. The assembly code examples on that page all show the registers stored at >5FF0 to >5FFF. Which makes sense because the disk system will work without memory expansion.

 

That makes even more sense in light of the table immediately following that statement. When I first read it, that disparity puzzled me.

 

...lee

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That makes even more sense in light of the table immediately following that statement. When I first read it, that disparity puzzled me.

 

...lee

Plus, if you do a search for >5FF it occurs 41 times on that page with instructions like:

MOVB @>5FF0,R6 Read FDC status register

 

RDY MOVB R0,@>5FF8 Send command to FDC command register

 

etc.

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Which Millers Graphics docs? Link?

 

 

Sent from my iPhone using Tapatalk Pro

I thought I typed the reference. Ah well. It was Millers Graphics The Smart Programmer monthly newsletter. I was reading the real, printed document.

 

Edit: Just got back home; the memory layout I looked at is in the March 1984 issue.

Edited by InsaneMultitasker
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I always wondered why TI Forth (and fbForth by inheritance) stayed clear of >FFF2 – >FFFF. The 82-byte Terminal Input Buffer (>FFA0 – >FFF1) is the highest memory used. Perhaps this is the reason—or not (per Harry's post above).

 

...lee

 

[Edits in this color.]

Hmm I told you guys it was for a future expansion paged memory created by TI, but never made it past set up stage.

 

It was mentioned on the side notes handwritten from my old XB ROM source I got from TI.

Edited by RXB
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Hey Rich, Are these handwritten notes scanned and archived anywhere? I can't remember reading this anywhere else? -j

 

 

Sent from my iPhone using Tapatalk Pro

I hand typed in all 5 inches of pages of the source including the handwritten notes and uploaded them to GENIE and the KEEP and other BBS.

 

I also mailed copies to numerous people after they asked for them on DISKs.

 

My computer SCSI Hard drive crashed and I lost all copies but to make matter worse I loaned the original hard copy to a buddy that lost them in a Portland Oregon flood.

 

So no unless someone has them from these copies I made we no longer have this source.

Edited by RXB
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That's discouraging! Do you still have the original hard drive? I had a hard drive crash and lost some pictures. I was lucky-it was the circuit board on the drive that failed. I got an identical drive on ebay and swapped out the board and was able to retrieve the pictures.

Sorry no I have extensive software on the Mac and Windows side to recover drive data and it was totally gone or corrupted beyond recovery.

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Wondering if those files are sitting around on some internet archive somewhere?

 

 

Sent from my iPhone using Tapatalk Pro

I have repeatedly asked the community to search archives for it including WHT FTP that had a copy uploaded to it.....no replies.

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Well, I looked in all my stuff for those files - I came up empty.

 

I came across some files that say IMYXB3 text and dsks - which are in a folder entitled RXB v2001 source - I don't suppose these are what you're looking for.

Sorry no this was done just before I released RXB 2001, at the time I think it was RXB version 5.55 released.

Edited by RXB
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