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Madskp.
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16 October 2025 at 13:27 #70501BRONZE Member
Hi.
For years I’ve been on look-out for the upgrade ROMs for the Beomaster 4500 to upgrade it to two-way comms. I finally grabbed a NOS set that I found on eBay (not cheap but wanted to get this over with) and I uploaded the BIN files of both 1.6 and 2.2 ROMs to archive.org. Please help sharing these ROM dumps before the old EPROMs eventually fail. I hope this helps somebody else to upgrade or repair their Beomasters.
I can now get two-way IR on a BL7000. I tried MCP6500 too but that didn’t work.
Anyone know if all BM4500’s actually shipped with the two-way IR hardware or were there one-way models too?
My BM4500 now has the new ROMs, new battery, transformer wiring switched from 220V to 240V. And new adhesive on the touch-panel (although it’s still not perfect, and some previous owner had chipped the black paint on several places but I was able to mask most of it). The tuner feels somewhat low-sensitive though.
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You must be logged in to view attached files.Location: Helsinki - FinlandMy B&O Icons:17 October 2025 at 15:41 #70536Madskp
GOLD MemberI first saw now that this was also posted here. Very great that you have made the software available :-). These softwares can be hard to track down if needed for a repair or an upgrade.
I might have a go at updating my BM4500 to 2way at one point in the future.
Would you happen to know if the eproms has to be the excact model or if other can be used?
Location: Denmark17 October 2025 at 16:04 #70538BRONZE MemberThanks!
With both BIN files you can write whichever version you want (two-way comms or the BM-as-link-room-mode only in 1.6, as you pointed out in Discord).
The chip in my unit (and the replacement) was a generic 27512 EPROM, which is still readily available. Mine was M27512FI, ie. by STMicroelectronics but any manufactorer should be fine (as long it’s the same 28-pin DIP package). I couldn’t find the speed rating for either chips, but in this case I’d guess the “slowest” 200ns part should work (elsewhere, like vintage computers the speed of the ROM might be important). You’ll also need an UV-eraser (for the old EPROMs with window on top) and an EPROM programmer. I’m sure there are also newer pin-compatible variants (EEPROMs, ie. no UV-erasing needed, or write-once chips if you just want to write a chip once and not re-use it).
I find it interesting that the BM4500 was shipped with the “limiting” software (if the 2-way IR hardware was fitted). Also the release notes telling a fix for “Beosystem 4500 may intermittently block and it is necessary to remove the mains plug” sounds pretty annoying bug, and surely would’ve caused calls to dealers! (I might have actually experienced this on my unit with the old ROM once or twice, I always thought it was just an effect of a low battery but apparently not!)
Location: Helsinki - FinlandMy B&O Icons:17 October 2025 at 17:06 #70540Madskp
GOLD MemberThe chip in my unit (and the replacement) was a generic 27512 EPROM, which is still readily available. Mine was M27512FI, ie. by STMicroelectronics but any manufactorer should be fine (as long it’s the same 28-pin DIP package). I couldn’t find the speed rating for either chips, but in this case I’d guess the “slowest” 200ns part should work (elsewhere, like vintage computers the speed of the ROM might be important). You’ll also need an UV-eraser (for the old EPROMs with window on top) and an EPROM programmer. I’m sure there are also newer pin-compatible variants (EEPROMs, ie. no UV-erasing needed, or write-once chips if you just want to write a chip once and not re-use it).
Thanks for the info. I have the EPROM programmer, but might have to get the UV eraser.
I find it interesting that the BM4500 was shipped with the “limiting” software (if the 2-way IR hardware was fitted). Also the release notes telling a fix for “Beosystem 4500 may intermittently block and it is necessary to remove the mains plug” sounds pretty annoying bug, and surely would’ve caused calls to dealers! (I might have actually experienced this on my unit with the old ROM once or twice, I always thought it was just an effect of a low battery but apparently not!)
Yes something about the software for this systems is like B&O was not sure what to do with it. The link room functionality is only described as being in slave mode and for future use in the user manual, so not very official. I wonder why they didn’t mentione it instead of saying for future use
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