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JohnnyRockets

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    Transfer directly to Stack?

    in 2600 Programming For Newbies

    Posted

    Thanks Stephen!

     

    Now looking at this snippet:

     

    ---------------------------

     

        processor 6502
        
        seg code
        org $F000        ; defines the code origin at $F000
        
    Start:
        sei                ; disables the interrupts
        cld                ; disable the BCD decimal map mode
        ldx #$FF        ; loads the X register with #$FF
        txs                ; transfers X register to S(tack) register
        
    ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
    ; Clear the Zero Page region ($00 to $FF)
    ; Meaning the entire TIA register space and also RAM
    ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
        lda #0              ; A = 0
        ldx #$FF          ; X = #$FF
        sta $FF            ; make sure $FF is zeroed before the loop starts
    MemLoop:
        dex                ; x--
        sta $0,X        ; store zero in A, at address $0 + X
        bne    MemLoop        ; loop until X==0 (z-flag set)
        
    ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
    ;Fill ROM size to exactly 4KB
    ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
        org $FFFC
        .word Start        ; reset vector at $FFFC (where program starts)
        .word Start        ; interrupt vector at $FFFE (unused in VCS)

     

    ---------------------------

     

    Question:  What values are now stored in $FFFC and $FFFE?  And why?

     

    My guess is  Zeros?

     

     

    Thanks!

     

     

    JR
       

     

    Transfer directly to Stack?

    in 2600 Programming For Newbies

    Posted

    Hi all,

     

    In the following "newbie" code snippet:

     

    --------------

     

        processor 6502
        
        seg code
        org $F000        ; defines the code origin at $F000
        
    Start:
        sei                ; disables the interrupts
        cld                ; disable the BCD decimal map mode
        ldx #$FF        ; loads the X register with #$FF
        txs                ; transfers X register to S(tack) register

     

    --------------------

     

    Could we have just loaded #$FF directly into the Stack register, thus saving a step/instruction?

     

     

    Thank you,

     

     

     

    JR

    TheC64 Full Size - Pre-orders Open for USA

    in Commodore 8-bit Computers

    Posted

    Hi all,

     

    I kind of did a "spur of the moment thing" last Sunday night...  I wanted to see if any "64 Maxis" were available anywhere in the US.

     

    I found one on the "iWoot.us" website, a website that sells a bunch of crazy stuff that appears to be all over the map as far as topics go.

     

    They had only one 64 available, so I bought it thinking they'd cancel the order once they realized that they didn't really have any in stock.

     

    But lo and behold, it shipped and arrived today, only 3 days later (from the UK - it is the UK version)!

     

    Honestly, it blew my mind!  It still kind of does!  LOL!

     

     

    JR

    • Like 2

    Tandy MC-10 / Alice

    in Tandy Computers

    Posted

    8 minutes ago, Michael Kline said:

    Hi JR,

     

    Yes I did. I received my first CoCo 2 when I was about 15 for Christmas. I thoroughly enjoyed it. I couldn't afford disk drives at the time. So, I was stuck using cassettes. We had a CoCo users group back then. So, we got to explore a lot of titles back then. 

     

    Later in my 20s, I was able to build out a full setup, including getting and upgrading a CoCo 3 to 512k.

     

    Times got very challenging in my late 30s. And I lost the entire collection. 

     

    I have started to rebuild. I have a 64K CoCo 2 and 512k/2MB CoCo 3. My CoCo 3 will automatically go to 2MB when I am able to get the CPU daughter board, that will give me 2 more address lines that I need for 2 meg. 

     

    The 8 bit computer era were the best times for me. So, now I can relive and enjoy those times again. 

     

    100% agree!  We sound about the same age, and those were awesome times  to  play with computers and now there are SO many great emulators out there you get to "try before you buy" so many of them!

     

    On that note I shot you a PM with a specific Coco2 question.

     

    Thx!

     

     

    JR

    • Like 1

    Tandy MC-10 / Alice

    in Tandy Computers

    Posted

    3 hours ago, Michael Kline said:

    I looked at the MC-10 back in the day. Although, I had already had a CoCo 2, I passed on the MC-10 because of it's limitations versus the CoCo. I have the emulator for the MC-10 on my laptop. And I played with it a little. However, I always went back to using my CoCo 2, and now my CoCo 3.

     

    If the MC-10 is your first look at the Colour Computer line of computers, definitely play with the emulator and see what you think about it, before you buy. The software for the Colour Computers are archived at www.colorcomputerarchive.com. Perhaps you have been there already.

     

    Some people pick up the MC-10 to add to or complete a collection.

     

    There are times that you will see a MC-10 listed on eBay for less than a CoCo 2. Other times for more. If you're looking for the "best bang for the buck", and you deciding between getting the MC-10 or the CoCo 2, go for the CoCo 2 or even the CoCo 3. They have a lot more capabilities. A SDC controller is today's perfect replacement for disk drives, and the archive is your oyster.

     

    The question is: Have you played with the Coco 2 or 3 lately? If not, the MC-10 will get your feet wet. If you have to make a choice and funding is low, go for a CoCo 2. It will do all the things the MC-10 does and much more.

    Hi Michael,

     

    I appreciate your thoughts greatly!  The Coco 2 is very nice as well.  I'm trying to grab a childhood "wished I had it" moment here and I specifically remember going to my local Radio Shack and "ooohing" and "ahhhing" over the Tandy Color Computers.  I ended up with the VIC-20, cause that was what I could afford with my Christmas money when I was 13 years old.  Now I can afford it ALL!  ;)  But I want to limit the technology, so the Coco 2 I will definitely look very close at, and I am intrigued with Assembly Language and do enjoy playing with that as well.  So we'll see how it all pans out....

     

    100% agree with the SDC controller idea, that is key if I make the jump from emulator to physical...  And, oh man yes, the color computer archive is a GREAT site!

     

    Thanks again Michael, and just curious if you had the Coco growing up or are just getting into it now?

     

     

    JR

    • Like 1

    Tandy MC-10 / Alice

    in Tandy Computers

    Posted

    Hi all,

     

    Just starting playing around with the MC-10 Color Computer.

     

    This is the one that I think I would have bought in addition to my VIC-20 way back in the day.

     

    I could have afforded it.  :)

     

    Anyone play with one of these?

     

    I might try to buy one.

     

    Thanks!

     

     

    JR

    • Like 2

    Which 8bit micro you wish you tried bitd?

    in Classic Computing Discussion

    Posted

    All I could think of was the Commodore PET.  Man, if I could just have owned that one!  Whew!

     

    $3000 was the price tag at that time and my Dad said, "I don't think so!".

     

    Settled for the VIC-20 later on with my allowance, but I still dream of learning more about how to program the "PET".

     

    I still may, but I just need to find a group or a forum or something that is really PET-centric, maybe on FB?

     

     

    JR

    Is a 6502 processor always a 6502 processor?

    in Atari 2600 Programming

    Posted

    Hi all,

     

    I have a question regarding the "general" learning/programming of the 6502 processor.

     

    I am currently learning ASM programming for the Atari 2600 and as I am studying, I am learning the specifics of the 6502 processor registers, etc. (nothing new here)

     

    Once I have a general understanding of the 6502 ASM "in's and out's", will it then be "somewhat" (certainly different in many ways) manageable to then move to programming other 6502 based machines?

     

    I would like to branch out to some of my childhood favorites (Commodore PET and VIC-20) as well in the future.


    What are your thoughts please?

     

    (apologies if this is an improper place for this post)

     

     

    JR

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