Copying a BBC Model B Microcomputer’s ROM

Retrieving my OZMON 1.1 ROM image was somewhat convoluted, as the backup copy on floppy disks had been lost during my 2002 attempts to create floppy disk images. However, I had an actual instance of OZMON 1.1 sitting in slot 13 of my real Beeb. Solution?

Use *SAVE to my Beeb’s cassette port whilst feeding the cassette audio out to the sound card input of a WinXP PC which itself is running a program such as bbctapedisc (http://8bs.com/othrdnld/utilities/bbctapedisc.zip) to receive and decode the audio. Had to adjust the volume of the audio input somewhat under WinXP while experimenting
with the transfer, but ultimately the following process worked.

On my WinXP host, launch bbctapedisc using:

bbctapedisc.exe -i -s -a image.ssd

On my Beeb:

Launch OZMON 1.1 (Use “*OZMON”)

From within OZMON, copy 8K of ROM space into RAM:

M&8000/&2000/&2000

Then execute to MOS commands to enable cassette mode, then save
the binary block of &2000 bytes starting at &2000 (i.e. the ROM image)

*TAPE
*SAVE "OZ11R" 2000+2000

Then pressed “RETURN” on the BBC Micro and it proceeded to “save” the
block of memory to tape.

The bbctapedisc application immediately started showing on screen that it was receiving blocks successfully. It took 32 blocks (&100 bytes each) to fully transfer the OZMON v1.1 ROM image. (First time there was failure between blocks &0E and &11, so I re-did the *SAVE using a slightly higher inbound volume on the WinXP side, which seemed to do the trick. The 2nd attempt worked with no blocks reported corrupt.)

Rename OZ11R to OZMON_v1.1.rom and we’re done.

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