The MAME 0.252 release capped off a wild 2 months for Apple emulation in MAME. I started off switching the Apple IIgs emulation to exclusively use the emulated ADB microcontroller, and eliminated a chunk of old simulation code dating back to MESS in 2005. I then extended MAME’s ADB keyboard emulation to include the extra keys that an Apple Extended Keyboard has, including function keys and Insert/Delete and that kind of thing. Kelvin Sherlock helped there with some keypad key issues as well.

A wild new contributor benrg appeared around that time and started off strong with some great simplification of our 8-bit Apple II video emulation. He followed that up by actually improving MAME’s Apple II high-resolution NTSC artifact emulation to better match real TVs, so for instance the “V” in Ultima V’s title screen now looks smoother, as the creators intended. It’s a relatively subtle difference if you aren’t A/Bing it, but it is a definite improvement. Most recently, he’s also improved the Double Hi-Res emulation code (more in terms of code quality than results) and fixed some bugs in the unique double hi-res modes provided in RGB monitor mode on the Apple IIe. benrg’s work caused project leader Vas Crabb to notice that I hadn’t properly gone to a getter/setter model when I split out the Apple II video to a shared file, so I gave that stuff proper separation. No user-visible effects, but the code is cleaner and easier to understand now.

The focus then shifted back to ADB emulation. With the Apple IIgs now sharing it some long standing issues came to light. Devices were always responding to ADB TALK requests even when they had no new data to offer, and the Service Request mechanism used for devices to tell the host that they had new data wasn’t emulated correctly. I was able to fix those issues without angering any of the ADB microcontroller types we now support (IIgs M50740 & M50741, Mac PIC1654, Mac “Egret” 68HC05, Mac “Cuda” 68HC05, and Mac PowerBook M50753) and in fact with them fixed, using ADB Macs now feels subjectively better, especially when switching between the keyboard and mouse.

I also added support for a jumper that was added to ROM 03 Apple IIgs machines that disabled the Control Panel, primarily intended for school environments. With the ADB microcontroller emulated and running it was easy, and it’s something no other released IIgs emulator does. More IIgs excitement comes in the form of adding preliminary support for the “Mark Twain” prototype. The prototype’s improvements included SIMMs for RAM expansion, a built-in SCSI hard disk and DMA SCSI controller, and a built-in Apple “SuperDrive” 1.44MiB floppy. Emulation of those last two features isn’t working yet, but you can still pop any of our working mass storage cards into the MT emulation to take it for a spin.

There was a bug in our emulation of the Macintosh real-time clock chip, which was also in the IIgs where it wouldn’t tell time on Windows host systems but was fine on macOS and Linux. That was fixed, so the Brutal Deluxe Dragon’s Lair games now work for Windows users.

Finishing off, I piggybacked off of some great work by fellow dev Kale bringing up PCI-based PCs by starting work on some PCI-based Macs. There are now preliminary not-working drivers for the PowerMac G3 (the original beige one) and the Bondi blue iMac (the first iMac).

And there’s more to come in 0.253, including fixes for regressions in the IIgs games Zany Golf, GBA Basketball, and Paperboy and NCR5390-family SCSI improvements that make the Mac Quadra 700 able to boot from a hard disk for the first time.

And if you’re curious about what all happened with MAME in 2022, I highly recommend this excellent video by MAME contributor The Mog Miner. There’s even some Apple II and Mac content.