HP-71B Enhanced Math LEX
08-11-2020, 04:24 PM (This post was last modified: 08-11-2020 05:39 PM by Dave Frederickson.)
Post: #36
 Dave Frederickson Senior Member Posts: 2,124 Joined: Dec 2013
RE: HP-71B Enhanced Math LEX
(08-11-2020 02:47 PM)Erwin Wrote:  ... Now in the 3rd run it was successful. Here is how I did it in the end - in my case original mathrom is in Port(5.01) on adress D0000:
Code:
POKE "D0000","B3DDDDDE" ... set RAM identifier POKE "2C004","95" ... config as RAM in the FRAM71 On/off FREE PORT(5.01) COPY MATH2B5:TAPE TO :PORT(5.01) POKE "D0000","00000000" ... remove RAM identifier POKE "2C004","D5" ... config as ROM On/off VER\$ ... recognized Math:2b

Just for information, the POKEs to D0000 have no significant effect. The first POKE to D0000 does nothing as the memory is initially ROM. You can verify this by PEEKing D0000. The second POKE to D0000 to remove the IRAM identifier has no significant effect for two reasons.

1. A ROM can run with an IRAM identifier - look at the Finance ROM.
2. The file copied to PORT(5.01) is a LEX file (I presume) which runs just fine in an IRAM.

Dave

EDIT: The fourth byte of a ROM contains a checksum, so by POKEing zeros to D0000 you're likely invalidating the checksum. See the ROMCOPY doc.