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Re: How does the Apple IIGS emulate a IIe?

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Kelvin Sherlock wrote:
> ---
> It's possible that everybody, including Apple, has been wrong for 37
> years but extraordinary claims require extraordinary evidence.
> 

I found articles going back to the 1986 release of the IIgs that described
the Mega II as a "complete Apple II on a chip." Most likely someone made an
assumption about the chip, and it spread around, was repeated, and stuck for
37 years. This happens in every knowledge domain, not just with vintage
computers.

Here's a post from September 1986 that asks if the Mega II is an emulator
chip:
https://macgui.com/usenet/?group=6&id=3010

Here's a reference to an October 1986 BYTE Magazine article about the Mega
II:
https://macgui.com/usenet/?group=1&id=3626


THE MEGA II
The Mega II is a custom CMOS chip containing about 3000 gates and a 2K-byte
by 8 ROM (for the character generator). It replaces the following chips from
the Apple IIe and IIe: char­acter generator ROMs for eight lan­guages.
several TTL chips that per­form logic functions. and the MMU (memory
management unit). IOU (in­put/output unit). TMG (timing genera­tor). and GLU
(general logic unit) custom chips.

In previous Apple II designs, the re­freshing of memory was tied directly to
the Apple II video mode. The Mega II includes an 8-bit counter for
refresh­ing the 128K bytes of (slow) memory associated with the Apple
IIe/IIc model; it does five cycles of RAM refresh during the horizontal
retrace of each video scan line and refreshes the 128K bytes of memory in
3.25 milliseconds. By taking care of RAM refresh the Mega II chip opens the
Apple II design to new video modes that were impossible before.

-- 
]DF$
The New Apple II User's Guide:
https://macgui.com/newa2guide/

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Thread

How does the Apple IIGS emulate a IIe? Mitchell Spector <mitch2gs@hotmail.com> - 2024-02-11 02:38 -0500
  Re: How does the Apple IIGS emulate a IIe? Antoine Vignau <ntn.vignau@gmail.com> - 2024-02-11 11:12 -0800
  The Mega II, was Re: How does the Apple IIGS emulate a IIe? D Finnigan <dog_cow@macgui.com> - 2024-02-13 17:56 +0000
    Re: The Mega II, was Re: How does the Apple IIGS emulate aIIe? D Finnigan <dog_cow@macgui.com> - 2024-02-13 18:04 +0000
      Re: The Mega II, was Re: How does the Apple IIGS emulate aIIe? Antoine Vignau <ntn.vignau@gmail.com> - 2024-02-13 11:42 -0800
    Re: The Mega II, was Re: How does the Apple IIGS emulate a IIe? Yeechang Lee <ylee@columbia.edu> - 2024-02-13 12:11 -0800
  Re: How does the Apple IIGS emulate a IIe? kelvin@pro-kegs.uucp (Kelvin Sherlock) - 2024-02-16 00:31 -0500
    Re: How does the Apple IIGS emulate a IIe? D Finnigan <dog_cow@macgui.com> - 2024-02-16 13:59 +0000
      Re: How does the Apple IIGS emulate a IIe? D Finnigan <dog_cow@macgui.com> - 2024-02-16 14:05 +0000
        Re: How does the Apple IIGS emulate a IIe? Mitchell Spector <mitch2gs@hotmail.com> - 2024-02-17 23:58 -0500
          Re: How does the Apple IIGS emulate a IIe? D Finnigan <dog_cow@macgui.com> - 2024-02-19 14:50 +0000
      Re: How does the Apple IIGS emulate a IIe? kegs@provalid.com (Kent Dickey) - 2024-02-19 21:56 +0000
        Re: How does the Apple IIGS emulate a IIe? D Finnigan <dog_cow@macgui.com> - 2024-02-20 14:09 +0000
          Re: How does the Apple IIGS emulate a IIe? kegs@provalid.com (Kent Dickey) - 2024-02-20 16:55 +0000
            Re: How does the Apple IIGS emulate a IIe? D Finnigan <dog_cow@macgui.com> - 2024-02-20 18:32 +0000
              Re: How does the Apple IIGS emulate a IIe? "James Hall [VE3MYZ] FN25dj. 73" <james.hall.ottawa@gmail.com> - 2024-02-21 23:34 -0800
  Re: How does the Apple IIGS emulate a IIe? David Schmidt <schmidtd@my-deja.com> - 2024-02-16 09:28 -0500
  Re: How does the Apple IIGS emulate a IIe? kegs@provalid.com (Kent Dickey) - 2024-02-19 21:45 +0000
    Re: How does the Apple IIGS emulate a IIe? Mitchell Spector <mitch2gs@hotmail.com> - 2024-02-19 19:37 -0500
      Re: How does the Apple IIGS emulate a IIe? Steve Nickolas <usotsuki@buric.co> - 2024-02-19 22:38 -0500

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