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Stuart

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Posts posted by Stuart

  2. Posted

    I've got a load of 27C64 / 27C128 / 27C256 EPROMs I've been given - about 25 in all. Far more than I would ever need. These will work in the bank-switched cartridge boards, yes? If so, anyone willing to take them to the Chicago fair to be shared out amongst interested parties? I'll post them to you from the UK.

     

    Stuart.

     

     

  3. Posted

    I would have to disagree with that Stuart.

    In RXB I use a command called CALL EXECUTE(cpu-address)

    And it is a just a BLWP @cpu-address

     

    So what I do is the CPU Workspace is where all the values are loaded before I call that routine. Thus all registers are pre-loaded and ready to go.

     

    That has to be one hell of a lot faster then having to fetch values after the XOP. 8 Registers are loaded and ready to execute before I even do the call.

    I was talking about the specific case of passing "a parameter" - just *one* parameter. XOP @>1234,R1 where the parameter >1234 is passed in the instruction itself uses one less instruction than having to MOV that parameter somewhere then calling BLWP which then retrieves it. It you want to pass *lots* of parameters, then there is of course no benefit at all.

  5. Posted · Edited by Stuart

     

    Now you're just showing off :) You're making my head hurt!

    Confuses the hell out of me too!

     

    I would think XOP is slightly quicker than a BLWP if you want to pass a parameter. So with your BLWP following by a DATA statement above, with the XOP you don't need to MOV your parameter value (from a register or elsewhere) to that DATA location?

    • Like 1

  6. Posted

    Oooh... Looking in the Editor Assembler manual, section 7.19, page 125, I see XOP is a Format IX instruction. It has two parameters. My head hurts! I thought it was a single parameter instruction. Going to have to read this carefully!

    Edit:

     

     

     

    The effective address. So, if my workspace (prior to XOP) was >8300, and I do a XOP R1,1 I should see >8302 in R11 of the XOP workspace, right?

     

    Time to fire up Classic99, ASM99 and Notepad++

     

    <clicks knuckles> :-D

    Yes, I think you're right. Also, if you do XOP @>FF00,1, the value in R11 will be >FF00.

     

    Now, what if you do XOP *R1,1? ;-)

  7. Posted · Edited by Stuart

     

    Not so! Here're a couple of excerpts from the E/A Manual explaining that XOP 2 is available and that XOP 1 may also be available:

     

    7.19 EXTENDED OPERATION--XOP
    ... This instruction is on all TI-99/4A Home Computers. However, some only support XOP 2 while others support both XOP 1 and XOP 2. To find out if your TI-99/4A computer supports the XOP 1 instruction, run CALL PEEK in TI BASIC and read one word at address >44. If the word is >FFD8, then XOP 1 is available. If it contains other data (most likely >FFE8), then XOP 1 is not available. ...
    ... XOP 1 is at address >44, with vectors >FFD8 and >FFF8. XOP 2 is at address >48 with vectors >83AO and >8300. The first entry in the vector is the new workspace address. The second entry is the new Program Counter address. ...

     

    ...lee

    The XOP instruction works, but because the address and workspace vectors they use are hard-coded in the ROM on the 4A, they are of limited practical use. XOP 1 and XOP 2 could be used if you put the code and workspace where the hard-coded values say, but the other XOP vector addresses are used for code in the ROM.

    • Like 1

  8. Posted

    I've used Sitopway (in Shenzhen) to do my boards recently--they produce high-quality boards for a very good price, and they are fast.

     

    Jim, do Sitopway have an 'online quote' facility? Can't see one with a very quick browse of their website. I'm looking at doing a small run of TM990 8-slot backplanes.

     

    Stuart.

  10. Posted

    I think the best way to go about this would be to have a program that read the data in from disk, and poked that data *after* itself, in CPU memory (so that in CPU memory we have the XB program and the data immediately following it). Then, somehow, we change the data pointers in XB such that when the program is saved to disk, the TI saves the program, *and* the data that was poked into memory. I don't know how to do this in XB, but I think it's possible, as I've seen programs that load themeselves, and their data as one big file.

     

    Systex, by Barry Boone, is a program that can do this.

  11. Posted

    Removing the chips will be a snap. My coworker has a professional desoldering station and wouldn't mind taking a few mins to remove those chips.

     

    Be aware that you'll probably find that two diagonally-opposite pins on each chip were folded flat against the board prior to soldering, so as well as melting/removing the solder you've also got to bend up a couple of pins that are soldered to the board. It's not just a case of melting the solder and the chips fall out ...

  13. Posted

    Also, Why CF and not SD? SD is definitely more compact, more universal, cheaper, and maybe even faster.

     

    Because to use SD you'll need a microcontroller as part of the interface. CF is far easier to interface to systems such as the TI, and is plenty fast enough to work at the speed of the TI.

  17. Posted

     

    I do have Minibug.

     

    Unless my ROMs are completely different, I see these bits changed:

     

     

     

    many other random errors follow....

     

    If you take the floppy card apart, are the ROMs original? http://nouspikel.group.shef.ac.uk/ti99/fdcard.htm

     

    Have you got other cards in the PEB that *do* work? That I think would rule out problems with the PEB power supply. Next I think I would replace the 5V regulator on the floppy card (because it's easy) then look at replacing the 74LS245.

  18. Posted

     

    It hangs when I power on the console.

    Have you got a MiniMem cartridge, then you can check the DSR? You'll need to power on the console first, then the PEB. Then with the MiniMem cartridge you need the following (IIRC):

     

    (1) From the MiniMem menu, select EasyBug.

    (2) C 1100 1 <Return> [Floppy LED should light]

    (3) M 4000 <Return><Space><Space>... [To read out memory]

     

    Compare the data you're getting against this: http://nouspikel.group.shef.ac.uk/ti99/dc1.txt. If you see errors, then a common point of failure is the 74LS245 on the floppy card, which runs rather hot and has a bit of a hard time.

    • Like 1
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