HP86 problem

[Alexkumt]

I thought of using the software emulator for HP87 to trace the cause of the problem through Disassembler.

everything I type on the keyboard appears on the screen correctly. in my opinion this hardware seems to work properly.

when the command line has been written and the enter key is pressed. the system does not digest what is written. ho is not intended correctly.

even if you wrote incorrect things, the system should respond with a syntax error. instead that damned mistake always appears.

I thought I would find help from an expert person in interpreting the disassembler part.

probably if there is some electrical noise in the hardware in that part. the problem could perhaps be traced back to them.

perhaps the previous owner of this computer installed a particular ROM. (but I don't seem to notice any tampering in the motherboard, which seems perfect with no changes or anything)

I thought that even if there is this problem. you could insert a module for CPM with Z80 and check carefully if the system works. in this way the main ROM is bypassed.

or get me a self test module to insert in the drawerRom