Home Page Forums MAME MAME 8bit Apples - Apple I, II, /// and the 16 bit GS

rfka: Do you have the actual machines/motherboards for any of these to take PCB pictures? It's generally not too hard to determine if they're II/II Plus clones or IIe clones, but more documentation is always nice.

Most of the archives I've uploaded should have MB pictures
This is a web collection, so if I find ROMs I try to find pictures to go with them - unfortunately that's not always the case.

Since there was a Grappler Powered sticker, howabout a Grappler Plus Powered sticker (saw this on ebay)





and I also came across an ad that mentioned how many grapplers were sold (as of 1986)

RE: Teleport
Once enabled, pause the game and type "DEDICATION" to hear the dedication.
During play, press Ctrl-^ to enable extra keys, then press
Ctrl-U for the E.T. message;
Ctrl-@ for the hint message;
Ctrl-M for a collection of messages from songs and other games like Berzerk.

I'm not sure if this is the right place to put this observation, quite possibly not. But I discovered that the Apple II Emulation mode in the Apple /// isn't quite working. The symptom was that if I pre-boot with the Apple II Emulation disk, then boot a DOS 3.3 disk, then enter the monitor with CALL-151, my interaction with the monitor pretty much doesn't work. Commands don't do what they're supposed to, it doesn't seem like it is really "hearing" me. I can do 9D84G and get back to the Applesoft prompt. I expect this is easily reproducible. The Apple II Emulation disk is available, e.g., at apple3.org, and I've yet to find a DOS 3.3 disk that didn't show the behavior.

Upon investigation, I think the issue is that the special Apple /// VIA registers that live in FFDx and FFEx (and control various things like processor speed, RAM page, zero page) are not being properly "hidden" when in emulation mode. When emulation mode is on, I believe those addresses should no longer be active, but instead should be protected from writes and be read from RAM. This is presumably why once you get into emulation mode, you can't get out again. Those FFDx and FFEx addresses happen to be right where the monitor's command tables are, which would explain why the monitor can no longer understand me. Even if the addresses are not triggering state changes, they are not returning the bytes that should be there in FFDx, FFEx.

I somewhat verified this interpretation by writing a modified monitor ROM to the Apple II Emulation disk that relocated those lookup tables elsewhere (into the cassette read/write area) and once the monitor no longer relies on values in that area, it works fine.

I'm afraid I'm not savvy enough with the MAME codebase to know how to fix this, but I think essentially the case is when emulation mode has been turned on (by setting the $40 bit in $FFE3?), reading from FFD0-FFFF should return values from the system bank and ignore any contributions from the VIA.

Sorry if I invaded an unrelated thread, I was hypothesizing that this is kind of a grab bag thread of Apple II-and-friends-related issues.

That's... probably true. And arguably more important now that we emulate the Titan card. I'll check it out, thanks!

Ok, it's fixed in current GitHub code. I can call -151 and execute A2 Monitor commands normally now.

Perfect, thanks! (And astoundingly quick work!) I managed to compile and launch it, and I too am now seeing the monitor working properly.

On the minus side, I think this confirms that A2 emulation mode stuff can't actually service slot IRQs since they go through the VIA. (RobJ and I were discussing that recently in email).

There's a note in the Level 2 Service Reference manual that I came across, which may be saying that. Not certain it's saying exactly that, but it is concluding the same thing.

Apple3ServiceRefMan1982-10.pdf

Page 10.3, it says ("Peripheral connectors")