Greg Andrzejewski wrote: > > Just type in at the basic prompt: > > > > PRINT PEEK(64447) > > > > If it says 255 it's the old ROM, no Unidisk. > > If it says 0 then it's the Unidisk ROM. > > Then 3 is the memory expansion model, will > > allow Unidisk, and 4 is memory expansion > > model, Unidisk, and bugs fixed. The IIc+ > > is the only one that returns a 5. > > My model returns 255, so it is the original ROM. Is there any advantage to > updating the ROM? Does it involve anything more than swapping a chip? I tend > to think not, because if it were it would probably be talked about more. Bill has explained the technical details of the EPROM change in an earlier post. As to the benefits of the firmware update, I turn to the venerable Apple II technical notes to glean the following snippets: Original IIc ( $FBBF = $FF ) o Can use the IIc external drive only o No AppleTalk firmware o PR#7 boots the second drive o Mouse firmware maps to slot 4 o Serial firmware does not mask incoming linefeed characters o Serial firmware does not support XON/XOFF protocol 3.5 ROM IIc ( $FBBF = $00 ) o Can use the IIc external drive and the UniDisk 3.5 drive o AppleTalk firmware maps to slot 7 o PR#7 returns the message "AppleTalk Off Line" o Mouse firmware maps to slot 4 o Serial firmware defaults to mask all incoming linefeed characters o Serial firmware supports XON/XOFF protocol The AppleTalk firmware is of no practical use, since the support hardware never made it out of the development stage. That leaves the support for the UniDisk 3.5 (and other intelligent SmartPort peripherals, such as Apple IIc hard drives), and improvements to the serial firmware. You lose the ability to boot from a second 5.25" drive with PR#7. I seem to recall that this firmware revision also made some other improvements, such as giving the IIc a full self-test, and some monitor improvements such as adding a mini-assembler, but I'd have to look at the firmware listing to confirm this. -- David Empson dempson@actrix.gen.nz