For anyone that cares, here is a list of the configurations of my HP 9825s. Notice there's some funny stuff here. Some are marked 9825A on the back but 9825B in the front next to the display. Several are marked 9825T under the paper cover. #4 says A on the back, B next to the display and T under the cover! You figure that one out! Many of them have a list, under the paper cover, of ROMs that are installed internally in the machine. The ROMs listed are not the same on every machine and they're listed in differnt orders. Also some machines have different amounts of memory. The box mentioned on some of them is a small box that extends out the back where the power cord plug in is located. It looks like a noise filter was added on to some of the machine. Some of these also have the operating system located in a plug ROM located in the side of the machine. Joe #1 9825A SN 1622A07600 also 1637A01402 on back OPT 002 23228 Bytes ROMS 98210A String - Advanced Progranmming 98211A Matrix 98214A 9826A Plotter- General I/O - Extended I/O Has OS ROM in the side 09825-87905 #2 9825B SN 1014A02207 no OS ROM Full Travel keyboard. Has box on the back. Inside paper cover it's marked " 9825T” and lists the following installed devices: 9872A Plotter, General I/O, Extended I/O, Advanced Programming, String, System Programming , Total Memory 61670 Bytes #3 9825A SN 1622A09285 SN 1725A00116 on back Has full travel keyboard and box on the back. has Opt 001 15036 Bytes ROMS 98210A String - Advanced Progranmming 98211A Matrix 98213A General I/O - Extended I/O 98216A Plotter- General I/O - Extended I/O Has OS ROM in the side 09825-87905 #4 9825A (but marked 9825B next to the display) SN 1014A02187 Full Travel keyboard and has the box on the back. Inside paper cover it's marked "9825T" and lists the following installed devices: 9872A Plotter, General I/O, Extended I/O, Advanced Programming, String, System Programming , Total Memory 61670 Bytes No OS ROM No plug in ROMs #5 9825A SN 1622A04464 has chicklet keys Inside paper cover it's marked " 9825A” and lists the following installed devices: 9872A Plotter, General I/O, Extended I/O, String, Advanced Programming, Matrix Opt 001 15036 bytes, Opt 002 23228 bytes. ROMS 98210A String - Advanced Progranmming 98211A Matrix 98216A 9872A Plotter- General I/O - Extended I/O (note: none of these ROMs should be in this machine!) HP 98034B HP-IB Interface HP 98034A HP-IB Interface HP 98032-Opt 85 16 bit I/O w/ HP 9885 Disc Interface ( Yes, it could operate two HP-IB interfaces. As long as they had different addresses.) #6 HP 9825A SN 1622A03718 Has cicklet keys. Option 001 15036 total bytes ROMS 98210A String - Advanced Progranmming 98217A 9885M Flexible Disk Drive 98216A 9872A Plotter- General I/O - Extended I/O Has OS ROM in the side 09825-87905 #7 9825A (but marked 9825B next to the display) Full Travel keyboard. Inside paper cover it's marked " 9825B” and lists the following installed devices: 9872A Plotter, General I/O, Extended I/O, Advanced Programming, String, System Programming , Total Memory 61670 Bytes ROMS 98211A Matrix Has large warning label on outside top warning the user not to install any ROMs other than the 98211 matrix ROM or the 98217A Flexible Disk Drive ROM. Installing any plug-in ROM that is already built into the calculator may cause damage the machine.