ROM programming
The ATW800/2 for the Mega ST bus features two flash ROMs that provide space for four 256 KB TOS images.
The DIP switch at the back of the card can select these ROMs. Looking at the DIP switch from the back of the card, the switches read 1 and 2 from left to right:
| Slot # | Sw1 | Sw2 | Default ROM |
|---|---|---|---|
| 1 | Down | Down | TOS 2.06 |
| 2 | Up | Down | Latest EMU TOS |
| 3 | Down | Up | Previous EMU TOS version |
| 4 | Up | Up | TOS 1.04 |
Disabling the ROMs
Depending on your board revision there are diffrent ways to disable the onboard TOS ROM.
Owners of a revision 1.1b (and later) card can simply pull the jumper marked with “ROM enable” on the card.
Owners of ATW800/2 with a revision of 1.1a can also use this red jumper but also need to do a tiny little bit of soldering. Due to a design mistake, the left pin of the jumper needs a connection to a 5V source. This is for example available at the 3rd pin from right of TRAM socket “SLOT 2” using a jumper wire on the backside of the card.
Owners card revisions before 1.1a need to remove the ROM chips from their sockets.
You can do this by using either a dedicated PLCC pulling tool (shown below on the left) or a thin but sturdy tool and carefully sticking it into the notches in the corners of the socket one side at a time. Gently remove the ROM chip by lifting it up a little on each side. After a couple of lifts, it will pop out.
