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

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On 7/31/26 06:26, Louis Ohland wrote:
> 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?

As a feasibility, yes.  As the McIDE is implemented, it would need a 
revision to have a flash instead of an EPROM, maybe moving from the CPLD 
to an FPGA to accommodate more logic, and then possibly dealing with 
level conversion as a side effect of that move.

> "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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