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  1. RetroChallenge Jan 2016: What's Next?

    Although I was able to collect data from a floppy drive via FPGA, I don't have a working prototype yet. The next steps include:
    • Discussing clock and data windows
    • Discussing IBM track format
    • Creating the front end of a floppy controller exposed to a programmer
    • Publish my IPython notebooks consisting of data capture and building each FPGA component in a Python-to-Verilog library
    • Deployment and testing on real floppies
    • More pretty pictures.


    A write-enabled controller ...
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  2. Lanier Model 103 "No Problem" word processor

    Quote Originally Posted by Chuck(G) View Post
    Is this the Lanier that uses hard-sector 8" floppies, 256-byte sectors backward MMFM? I deciphered a couple of those years back. Sorry, don't have any program disks, just data.
    What is backward MMFM? Hmmm...

    MMFM is a (1,4) RLL encoding- I guess it requires a more precise sensor than MFM, a (1,3) RLL encoding, due to the higher number of sequential 0 bits (lack of transition).
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  3. 386 Video Boot Issue

    Quote Originally Posted by SpidersWeb View Post
    Old VGA cards often test the connector to determine if a display is colour or monochrome, when using a newer VGA monitor it often gets confused and results vary.
    I only have a couple of Trident cards which do this - so I make sure to use these with old CRTs - otherwise I try and use a different card that doesn't do it.
    Hmmm... how can video cards tell the difference? Was there something in the original VGA standard/original VGA signaling that made this possible?
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  4. Allocating RAM with int 21h- A guide to MZ gotchas

    Quote Originally Posted by wrljet View Post
    Mike,

    When any program in DOS gets control, it has all of memory allocated to it. You need to free the memory beyond the end of your program with INT 21h/AH=4Ah, before you can allocate anything more (other than from UMBs) with INT 21/AH=48h.

    Code:
    	mov	segPSP,es		; Save segment of PSP
    
        ....
    
    ; Free extra memory
    	mov	ax,ds			; Segment of DGROUP
    	lea	bx,ZTAIL+@STKSIZE+15	; Size of DGROUP, rounded up to para
    ...

    Updated October 20th, 2014 at 10:10 PM by cr1901

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  5. TRS-80 Emulation on a 5150 PC...

    Quote Originally Posted by Al Hartman View Post
    Quote Originally Posted by vwestlife View Post
    Which brings to mind... did anyone ever make a plug-in Z80 card for PCs?
    Yes, there was a card similar to the Microsoft Z-80 Softcard for the Apple ][ for the PC. It was called the Baby Blue ISA Card.
    Note to self... get hands on one of these.
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