Parsec

Gazoo · September 9, 2015

Ever since I got my HSGPL card, I've wanted to load Parsec on it. But I couldn't, because it's hard coded to run from the first Grom page, and I need XB to be there.

I assume nobody's ever figured out how to change the hard coding to another page, because I've never seen anything mentioned about it.

Well, after studying the source code, I finally figured it out. There are 20 values in the ROM file that need to be changed. The original values will be one of 3 hex words >9800, >9802, or 9C02. To change the Grom page that Parsec will run from, these values must be increased by 4 for each successive page that Parsec is modified to run from. So to run Parsec from page 2, one would change the values to >9804, >9806, and >9C06. To run it from page 16, as I do, the values would need to be changed to >983C, >983E, and >9C3E.

The following is the list of ROM memory addresses that need to be changed. I list them that way because there are different formats that the file can be in: no header, 4 byte header, and 6 byte header. The addresses listed are those that the computer responds to, not the absolute addresses of the ROM file. No change needs to be made to any of the Grom files, only the ROM file.

Here's the addresses:

>64EE

>64F4

>6530

>6662

>6690

>66BC

>7656

>7C4C

>7C52

>7C5C

>7CBA

>7CBE

>7E08

>7E0E

>7E24

>7F50

>7F56

>7F88

>7FB4

>7FB8

If you don't find >9800, >9802, or >9C02 at all of these addresses, you're not looking in the right place or you've got the wrong file. Don't alter anything unless you've got the correct data to begin with.

Have fun with Parsec!

Gazoo