C65 ROM status?

append delete Terlisimo


I'm wondering what's the preferred ROM image to use for testing and debugging.

Makefile creates MEGA65.ROM from 910111-390488-01.bin

In Paul's c65 PCB prototype demo on Youtube I see he's using ROM with checksum $4BCF, and timestamp is 911001.

This corresponds to rom image 911001.bin from, although that one has a BASIC demo built in that runs on startup, which obviously isn't present in Paul's demo.

I can't get the freezer to work, and I suspect it's down to the ROM image I'm using. running this on nexys4ddr fwiw.

What's the general idea regarding the c65 rom, will the project just use the old rom or maybe modify it? Possibly rewrite?


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append delete #1. adtbm

Hi Terlisimo,

the ROM image is the 911001 and to get the freezemenu working you need the
Freezemenu.m65 on your SD-card.
Here is a link to an SD imagae in my dropbox, where the freezemenu is in:

append delete #2. Terlisimo

Thanks for the image! I put FREEZER.M65 on the sdcard but still nothing happens.

It just goes into this loop:

,0777202A 20 20 33 JSR $3320
,07773320 9D 00 13 STA $1300,X
,07773323 E8 INX
,07773324 20 CF FF JSR $FFCF
,0777FFCF 00 00 BRK $00
,0777202A 20 20 33 JSR $3320

As if there should be something at $FFCF but that part of memory (kernal rom?) is just zeroes. This is in c65 mode. In c64 mode it just goes into BRK loop at

,0777E39C 00 00 BRK $00

...with SP going from $BEFF to $BE00 until it wraps around.

The left segmented display goes from displaying 0400 to 4000 when the freeze menu should pop up. Long-pressing the restore key still reboots the machine so it's not completely dead.

Was freezer tested on a nexys4ddr board? I see that the mega65 prototype uses the larger xc7a200t FPGA...

append delete #3. adtbm


yes, this image is from the SD-Card which i am using in my Nexys4DDR.
Did you use the fdisk function to partition and format the SD-Card, before putting the
files into the fat32 partition ?

append delete #4. Terlisimo

That was it! I probably just left it factory formatted. Feeling rather stupid now :)

It seemed to work because it loaded the bitstream and ROM from the card but the freezer didn't work.

append delete #5. adtbm

No worries, i had exactly the same problem the first time ;-)
Have fun !


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