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Re: Interesting Re: Decompiling the Reference Diskette and associated programs

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MAJ Tom discovered the "fencing off" of certain address ranges during 
boot. So this using 0xC000 is not a chance coincidence, but the result 
of IBM engineering.

Note that this requires a remote system, could that include a flash ROM 
with FAT12 file system?

"Virtual serial floppy drive
The virtual serial floppy allows the computer to boot any floppy 
diskette (e.g., a reference diskette), even when a floppy drive is not 
connected to the computer. The virtual serial floppy drive requires two 
computers, one that receives the data, and one that hosts the virtual 
floppy drive. The two computers are connected via a null modem cable.

Once the two computers are connected via serial cable, on the sending
computer open the serdrive.exe utility and specify the diskette image to
use (e.g., c:\serdrive reference_disk.ima ). Boot the receiving
computer, pressing F6 when XUB is detecting the attached drives. If
you wish to boot from the virtual floppy, press F2. To exit the serial
drive utility, press ctrl+c on the host computer. You can optionally
specify another diskette to attach.

Details regarding additional options are available online."

"JP1
JP1 is not used in normal operation. When the adapter is not configured,
connecting this jumper will force the ROM to respond at address 0xC000, 
which would cause the machine to boot from the BIOS even without having
configured it. You could then use the virtual serial floppy to boot a 
reference disk, allowing you to configure a machine with a missing or 
defective floppy drive."


Kevin Bowling wrote:
> On 7/30/26 21:53, Louis Ohland wrote:
>> Kevin, how do we access the larger BOOT ROM that is on the McIDE?
>>
>> So... the system boots from the original ROMs on the sysboard, then 
>> once POS has configured the system, then the control is passed to the 
>> flash on the McIDE?
>>
>> I suppose an analogy could be accomplished with an updated ethernet 
>> NIC which supports the bigger flash ROMs?
>>
>> Kevin Bowling wrote:
>>> That sounds cool.  There are some machines where slots are at a 
>>> premium so it would be ideal there.  For those where it isn't, maybe 
>>> easier to extend something like the McIDE which I think has boot 
>>> hooks, and it could all reasonably fit in an external flash boot ROM 
>>> BIOS, including all system types and all ADFs?
> 
> The BIOS hook is standard adapter option ROM.
> 
> McIDE has an interesting mode where a jumper JP1 allows it to boot on an 
> unconfigured system: 
> https://theretroweb.com/expansioncard/documentation/mcide-user-manual-v1-1-h1-0-6754aa5ae18c6582768777.pdf 
> 

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Decompiling the Reference Diskette and associated programs "Josh Rodd" <joshua.at.rodd.dot.us@rodd.us> - 2026-07-30 17:57 +0000
  Take me to the PROM Re: Decompiling the Reference Diskette and associated programs Louis Ohland <ohland@charter.net> - 2026-07-30 20:07 -0500
  Re: Decompiling the Reference Diskette and associated programs Kevin Bowling <kevin.bowling@kev009.com> - 2026-07-30 19:59 -0700
    Interesting Re: Decompiling the Reference Diskette and associated programs Louis Ohland <ohland@charter.net> - 2026-07-30 23:53 -0500
      Catching the Night Train Re: Interesting Re: Decompiling the Reference Diskette and associated programs Louis Ohland <ohland@charter.net> - 2026-07-30 23:58 -0500
      Re: Interesting Re: Decompiling the Reference Diskette and associated programs Kevin Bowling <kevin.bowling@kev009.com> - 2026-07-30 23:08 -0700
        Re: Interesting Re: Decompiling the Reference Diskette and associated programs Louis Ohland <ohland@charter.net> - 2026-07-31 08:26 -0500
          Re: Interesting Re: Decompiling the Reference Diskette and associated programs Kevin Bowling <kevin.bowling@kev009.com> - 2026-07-31 10:41 -0700

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