HP97 The journey begins

[teenix]

Hi all,

More progress :-)

The HP2240B now seems to be accepting all the print commands under the control of the HP-97 microcode. There were no changes to the original microcode, so from its point of view it is still connected to the 97 printer. It is a bit slower than the original 97 printer which is to be expected.

I had to delve into the 97 microcode to find a way of knowing when the last of a print line has been compiled. This was a bit of a task because there is more than one path for the print code to execute, but in the end the solution was "fairly" simple.

Once the end of the print line is detected, the characters originally for the PIK character ROM need to be re-formatted for the HP2240 printer and sent over the IR link. A full graphical print line needs to be sent and this takes a bit of time. As the HP2240B does not have handshaking, the PIC has to wait until it thinks the IR printer had finished its job before sending other lines if required. This can be up to 1.8 seconds according to the manual.

There is one last task I may as well do while I am in the guts of the project which is to create the notes mode. This is where the 97 can display and print stored messages either from certain keypress combinations, or from a running program similar to the 65/67 CPU boards.

However, as I found out with the 97 emulator, making this work with the 97 printer is quite a difficult task.

cheers

Tony