Groups | Search | Server Info | Login | Register

Groups > comp.sys.apple2 > #48868

Re: How does the Apple IIGS emulate a IIe?

Show all headers | View raw

Kent Dickey wrote:
> In article <dog_cow-1708091984@macgui.com>,
> D Finnigan  <dog_cow@macgui.com> wrote:
>>
>>
>>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.
> 
> I don't know the source of the above paragraph and what it's trying to
> say,
> but I do not believe it is correct. 

The source is the October 1986 BYTE Magazine article by Gregg Williams,
senior technical editor at BYTE.

It's on page 86 of the issue of BYTE magazine dated October 1986.


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

Back to comp.sys.apple2 | Previous | Next — Previous in thread | Next in thread | Find similar

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

csiph-web