The following warnings occurred:
Warning [2] count(): Parameter must be an array or an object that implements Countable - Line: 795 - File: showthread.php PHP 7.4.33 (FreeBSD)
File Line Function
/showthread.php 795 errorHandler->error





Post Reply 
Unused registers on 67 and 97
11-07-2022, 01:04 PM
Post: #1
Unused registers on 67 and 97
Hi all,

I think I got Flu or Covid from visiting my grand-daughter who was coughing relentlessly, and have been quite ill for a week or so, bless her little soul, but I'm sick of being sick so I tried to get the brain working again today.

As per the mention of the non-use of these registers for the 67 and 97 in this thread, I decided to see if they can be utilized in anyway. There are located at addresses $3A, $3B and $3C.

There is very little spare code space left in these calculator ROMs, (about 8 useable words) so I wasn't optimistic about being able to do anything. There is also another 8 in Bank 1, but to use them, the code must be executing in Bank 1 already.

As luck would have it, I did manage to make use of these RAM registers by using 7 of the spare ROM words. This mode can be enabled/disabled on the Teenix 67 emulator, which changes the assembler files, and when enabled, by using the RAM swap keys [F] [P<>S], 13 registers are swapped instead of the usual 10.

Indirect addressing for these 3 registers still doesn't work, but either way, there is no more ROM to make any further changes unless it is a simple modification.

I'll do the 97 emulator soon and then try and give the option on the CPU boards.

cheers

Tony
Find all posts by this user
Quote this message in a reply
Post Reply 


Messages In This Thread
Unused registers on 67 and 97 - teenix - 11-07-2022 01:04 PM



User(s) browsing this thread: 2 Guest(s)