View Single Post
Old 4th Oct 2020, 8:33 pm   #418
JohnBHanson
Heptode
 
Join Date: Aug 2009
Location: Worthing, Sussex, UK.
Posts: 573
Default Re: Gemini 80-Bus System

Really what I have done is use the first sector of the hard disk and
make it a .com file.

What the boot rom should do is to read the first sector of the hard disk, copy
80h bytes to location 0 and run that.

The boot rom will have to do other things, such as initialise the uart and
memory management on a gm813 as well as set the drive characteristics
if you want to provide compatibility with the xebec. Also best to perform
a reset to the svc card and then read/flush the svc input buffer. finally
read in the boot sector of the hard disk to ram and then copy 80h bytes
down to location 0 and from location 2 I think.

Still this gives you a lot of confidence in your hardware setup.

PS - I think the program I gave you will only boot the mfb system - so be careful if you
change your boot -0/1 configuration.

Pleased you have made good progress. What boot eeprom came with the
machine?

Last edited by JohnBHanson; 4th Oct 2020 at 8:38 pm.
JohnBHanson is offline   Reply With Quote