If you've got no other way of getting files from your PC to your BBC, you can run a short BBC BASIC program on your BBC and use terminal software on your PC to send a copy of the ROM to the BBC.
If you use a second processor, switch it off and press CTRL+BREAK. Then type in the following program at the BASIC prompt.
10S%=&FEFF:D%=&FEFE
20IF?(S%AND8)=0:STOP
30MODE128:MODE135:HIMEM=HIMEM-&4000:A%=HIMEM:REPEAT:V%=?D%:UNTIL(?S%AND1)=0:PRINT;~HIMEM:REPEATREPEATUNTIL(?S%AND1)<>0:?A%=?D%:A%=A%+1:PRINTCHR$13;~A%;:UNTILFALSE
Run it with RUN. If you get a STOP at line 20, the Tube Serial
device wasn't detected - make sure everything is connected!
Wait until the display reads 3C00 or similar. Then send the file
from your PC or Mac. (See below for the details.)
As the file transfers, you'll see another hex number count up. When it stops counting up, the transfer is complete. Press ESCAPE to get back to BASIC.
If you've got a disk drive, note the addresses printed and use *SAVE
to save from the first address to the second. For example, if the
first address is 4000, and the second is 5F62, *SAVE BLFS 4000 5F62. Then use your usual tools to get this loaded into ROM.
If you use RTOOL, the ROM
is hopefully already at the right address for use with its P
command.
Download Hercules from http://www.hw-group.com/products/hercules/index_en.html
Select the appropriate port, set Handshake to RTS/CTS, then click
Open.
Right click the window, and select Send File > Send File.... Find
the Tube Serial ROM and click OK.
Download CoolTerm from https://freeware.the-meiers.org/.
Run it and click Options on the tool bar. Select the appropriate
port from the list, set Flow Control is set to CTS, and click
OK.
Click Connect on the tool bar.
Click Connection > Send Text/Binary File..., select the Tube
Serial ROM, and click OK.