Since winter has finally arrived again I got back to my project. Thanks to Adrian's Digital Basement on YouTube who ran into the same issue with a ROM 0 to ROM 1 upgrade, I discovered the ROM image I had used was wrong. Specifically, it was inverted. Bank 1 and bank 0 were reversed. Of course it didn't work. I used the correct image with my changes incorporated, and the GS now works.

I think the wrong ROM came from an emulator web page. Do some emulators require the ROM image to be inverted?

The correct ROM was here;
https://mirrors.apple2.org.za/Apple%20II%20Documentation%20Project/Computers/Apple%20II/Apple%20IIGS/ROM%20Images/

Hi Mike,
Nope, no emulator requires the ROM image to be inverted.
Antoine

Antoine Vignau wrote:
> Hi Mike,
> Nope, no emulator requires the ROM image to be inverted.
> Antoine
>

I just checked with KEGS. I think Mike is right. The ROM on the
documentation project has indeed the banks swapped compared to the ones that
KEGS recommends to use. The README.ROM.files.txt in KEGS explicitly excludes
the ROM from the documentation project:

"APPLE Computer and Peripheral Card Roms Collection.zip: Don't use, the
file Apple IIgs ROM1 - 342-0077-B - 27C1001.bin is not in the
format KEGS expects."

I also tried to upgrade my ROM0 using the APPLE2GS.ROM image that KEGS uses
and had the same experience. It did not work so I ended up buying one
instead.
It would be interesting to know why there are these two formats out there.

In article <cybernesto-1639236775@macgui.com>,
cybernesto <cybernesto@macgui.com> wrote:
>Antoine Vignau wrote:
>> Hi Mike,
>> Nope, no emulator requires the ROM image to be inverted.
>> Antoine
>>
>
>I just checked with KEGS. I think Mike is right. The ROM on the
>documentation project has indeed the banks swapped compared to the ones that
>KEGS recommends to use. The README.ROM.files.txt in KEGS explicitly excludes
>the ROM from the documentation project:
>
>"APPLE Computer and Peripheral Card Roms Collection.zip: Don't use, the
> file Apple IIgs ROM1 - 342-0077-B - 27C1001.bin is not in the
> format KEGS expects."
>
>I also tried to upgrade my ROM0 using the APPLE2GS.ROM image that KEGS uses
>and had the same experience. It did not work so I ended up buying one
>instead.
>It would be interesting to know why there are these two formats out there.

KEGS expects the ROM file it uses to be in memory order, so for ROM.01,
it wants the byte for $fe/0000 first, and ending with $ff/ffff. Why does it
expect that? Since that's the easiest way to dump out the ROM from a real
IIgs to transfer the data to your current PC.

In the years since KEGS was created, MAME has added IIgs support. MAME has
a different emulation strategy--they like to dump out the ROMs directly using
a direct device reader, and then use that data. The problem with this
strategy is very few people in the world have the ability to dump out their
own ROMs in this way--so folks using MAME sort of have to get the ROMs from
a ROM repository. You can identify ROMs for MAME since they're the only
ones giving part numbers for the ROMs (the 342-0077-B stuff).

Combine this with another issue: MAME has a lot of smart people figuring
stuff out, but they don't seem to like to document what they discover or
notify others of issues. So this is the first time I've heard that the ROMs
themselves may be in a different order than what KEGS has been using for
25 years. Now that I know this issue exists, I can look into making KEGS
accept ROMs in either order.

And even then, this is mostly speculation--I'm assuming MAME didn't store
their ROMs in a weird format for no reason, etc. Your data, that burning
the MAME format ROMS works on a real IIgs, is the piece of data I didn't
have previously.

Kent

kegs@provalid.com (Kent Dickey) writes:

> In article <cybernesto-1639236775@macgui.com>,
> cybernesto <cybernesto@macgui.com> wrote:
>>Antoine Vignau wrote:
>>> Hi Mike,
>>> Nope, no emulator requires the ROM image to be inverted.
>>> Antoine
>>>
>>
>>I just checked with KEGS. I think Mike is right. The ROM on the
>>documentation project has indeed the banks swapped compared to the ones that
>>KEGS recommends to use. The README.ROM.files.txt in KEGS explicitly excludes
>>the ROM from the documentation project:
>>
>>"APPLE Computer and Peripheral Card Roms Collection.zip: Don't use, the
>> file Apple IIgs ROM1 - 342-0077-B - 27C1001.bin is not in the
>> format KEGS expects."
>>
>>I also tried to upgrade my ROM0 using the APPLE2GS.ROM image that KEGS uses
>>and had the same experience. It did not work so I ended up buying one
>>instead.
>>It would be interesting to know why there are these two formats out there.
>
> KEGS expects the ROM file it uses to be in memory order, so for ROM.01,
> it wants the byte for $fe/0000 first, and ending with $ff/ffff. Why does it
> expect that? Since that's the easiest way to dump out the ROM from a real
> IIgs to transfer the data to your current PC.
>
> In the years since KEGS was created, MAME has added IIgs support. MAME has
> a different emulation strategy--they like to dump out the ROMs directly using
> a direct device reader, and then use that data. The problem with this
> strategy is very few people in the world have the ability to dump out their
> own ROMs in this way--so folks using MAME sort of have to get the ROMs from
> a ROM repository. You can identify ROMs for MAME since they're the only
> ones giving part numbers for the ROMs (the 342-0077-B stuff).
>
> Combine this with another issue: MAME has a lot of smart people figuring
> stuff out, but they don't seem to like to document what they discover or
> notify others of issues. So this is the first time I've heard that the ROMs
> themselves may be in a different order than what KEGS has been using for
> 25 years. Now that I know this issue exists, I can look into making KEGS
> accept ROMs in either order.
>
> And even then, this is mostly speculation--I'm assuming MAME didn't store
> their ROMs in a weird format for no reason, etc. Your data, that burning
> the MAME format ROMS works on a real IIgs, is the piece of data I didn't
> have previously.

MAME ROMs for the Apple IIgs are in the same order as KeGS uses.

My MAME Apple IIgs ROM 01 ZIP file's ROM:
unzip -p ~/.mame/roms/apple2gsr1.zip 342-0077-b |sha1sum
e4fc7560b69d062cb2da5b1ffbe11cd1ca03cc37 -

I have a pretty up-to-date build of MAME, fwiw.

My KeGS ROM 01 file (filename "ROM"):
sha1sum ~apple2/emulators/kegs/ROM
e4fc7560b69d062cb2da5b1ffbe11cd1ca03cc37 /extra/apple2/emulators/kegs/ROM

I think the OP's flipped-bank ROM file was probably just messed up. Or
perhaps it is for an emulator other than either of KeGS or MAME.

--
--
Jerry awanderin at gmail dot com

>
> I think the OP's flipped-bank ROM file was probably just messed up. Or
> perhaps it is for an emulator other than either of KeGS or MAME.
>

The following ROM images have the same sha1sum and work on KEGS:
https://mirrors.apple2.org.za/ftp.apple.asimov.net/emulators/rom_images/gsrom01.zip
e4fc7560b69d062cb2da5b1ffbe11cd1ca03cc37 *xgs.rom
https://mirrors.apple2.org.za/ftp.apple.asimov.net/emulators/rom_images/iigs_rom01.zip
e4fc7560b69d062cb2da5b1ffbe11cd1ca03cc37 *iigs_rom01_APPLE2GS.ROM
https://mirrors.apple2.org.za/ftp.apple.asimov.net/emulators/rom_images/rom01.zip
e4fc7560b69d062cb2da5b1ffbe11cd1ca03cc37 *rom01_APPLE2GS.ROM

These ROM images on the other hand do not work with KEGS:
https://mirrors.apple2.org.za/ftp.apple.asimov.net/emulators/rom_images/APPLE%20Computer%20and%20Peripheral%20Card%20Roms%20Collection.zip
90ae5cbd5dff056bf39e44bde76f150e18956d33 *Apple IIgs ROM1 - 342-0077-B -
27C1001.bin
https://mirrors.apple2.org.za/Apple%20II%20Documentation%20Project/Computers/Apple%20II/Apple%20IIGS/ROM%20Images/Apple%20IIGS%20ROM%2001%20-%20342-0077-B.bin
90ae5cbd5dff056bf39e44bde76f150e18956d33 *Apple IIGS ROM 01 - 342-0077-B.bin

But if you try to build the adapter below, the KEGS compatible versions do
not work. Only the last two work.
https://www.applefritter.com/appleii-box/GS03_IIGSLRomReplacement.htm