There are guides online, the differences are documented, I believe you can tell from the outside. Bezel color is not always a 100% indicator. Floppies are at least easy for them! If no one else can do it, ping me and I can run off a set. Thanks, Jonathan ??????? Original Message ??????? On Wednesday, August 11th, 2021 at 10:37, Tom Uban via cctalk <cctalk at classiccmp.org> wrote:

Hi Tom, On Wed, Aug 11, 2021 at 09:37:24AM -0500, Tom Uban wrote: You have an 820-II; the original 820 only has two ROMs (U63, U64). ... I must have worked on mine right before someone put those files on bitsavers. I vaguely remember some alternate ROM version that supported a newer style keyboard, and was incompatible with my older setup, but I do not remember specifics. Labels in the e-bay photos also support that. I can able to help you with floppies. The floppies are standard IBM 3740 Single Density and easy to write with Imagedisk software and a PC-connected 8" drive. My 820-II currently boots and runs from disk images on SD cards, via a Lotharek HXC floppy emulator, with appropriate cable wiring. I used images found on the internet, and some I created from very old floppies of mine using Imagedisk on a PC with an 8" floppy connected. I highly recommend the Lotharek HXC floppy emulators. My only wish is the display on the floppy-form-factor version were easier to read. Both the swithing supply in my 820-II and it's external 8" drive box had failed. I replaced the supply in the 820-II case with a modern switching supply that easily fit. The HV bleeder resister for my CRT was arcing, so I replaced that. I replaced all the electrolytics on the monitor board. I also replaced the sockets for my ROMs, as some of their contacts "sprung" when I replaced the chips, but I do not recommend doing this unless it is absolutely necessary and you have good tools and practice. The 820-II restoration was a fun and rewarding project. It is well documented, easy to work on. It was also my first ever CP/M computer. When I was in high school, the 820 motherboards were readily available for $75. Mark -- Mark G. Thomas <Mark at Misty.com>, KC3DRE

Tom, On Wed, Aug 11, 2021 at 11:05:59AM -0500, Tom Uban wrote: If you still have any 8" floppies from your Big Board, these will probably boot and work in the 820 as well as 820-II. ... This adapter is useful: http://www.dbit.com/fdadap.html But, if your floppy doesn't require a TG43 signal, you could just wire a custom cable with no logic needed, or get something like this on e-bay: https://www.ebay.com/itm/114924378003 Additionally, some PC floppy controllers do not work for some kinds of floppy encodings. Here is the article I used as a guide. I've been using an Adaptec AHA-1522A SCSI+Floppy interace, which has a good FDC chip for optimum floppy format support. https://retrocmp.de/fdd/general/disk-imaging.pdf I'm all for not fixing it if it's not broken. But, I do suggest careful inspection of the electrolytics on the motherboard and monitor, especially since the monitor board is right above the logic board, so if a cap phsically leaked, the corrosive stuff that comes out could drip onto the logic board. I see this mostly in SMD style electrolytics, but have seen those like the ones in my 820-II physically leak, and the damage can be serious. -- Mark G. Thomas <Mark at Misty.com>, KC3DRE