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TonyDuell · 30th Apr 2018, 6:02 pm

It's a custom HP CPU. In fact the only standard ICs on the HP85 processor board are the RAMs (4116 16K*1 DRAMs). The OS is essentially ROM basic (but a reasonable BASIC). There's also the HP9915 (not to be confused with the 9815) which is an HP85 repackaged into a half-width rack module, essentially.

The HP75 is a closely related handheld/portable machine with a compatible CPU. I know the source listings of the HP75 ROM are available (with some hilarious comments....) but I've never seen the sources for any of the HP85 family.

Another machine that looks similar is the HP9826 (I believe this was the replacement for the HP85). Built-in small CRT but with a 5.25" floppy drive where the tape drive would be, no internal printer, but HPIB as standard. That has a 68000 inside...

30th Apr 2018, 6:02 pm	#3
TonyDuell Dekatron Join Date: Jun 2015 Location: Biggin Hill, London, UK. Posts: 5,215	Re: HP80 Series Computers (HP85, HP86, HP87) It's a custom HP CPU. In fact the only standard ICs on the HP85 processor board are the RAMs (4116 16K*1 DRAMs). The OS is essentially ROM basic (but a reasonable BASIC). There's also the HP9915 (not to be confused with the 9815) which is an HP85 repackaged into a half-width rack module, essentially. The HP75 is a closely related handheld/portable machine with a compatible CPU. I know the source listings of the HP75 ROM are available (with some hilarious comments....) but I've never seen the sources for any of the HP85 family. Another machine that looks similar is the HP9826 (I believe this was the replacement for the HP85). Built-in small CRT but with a 5.25" floppy drive where the tape drive would be, no internal printer, but HPIB as standard. That has a 68000 inside...