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Re: 6502 CPU Schematics
Henry S. Courbis wrote:
Hello Michael.
Finding a full microcontroller (as opposed to a simple state machine)
would really surprise me.
Really? That does tend to agree with what I saw on the die. Nothing I
could identify as RAM/ROM or anything segregated in to sections like a CPU
is. I just assumed I was missing something. Maybe it's a bit simpler of a
device then I thought - just a simple ASIC.
It is an ASIC. The IWM was inspired by the (at the time) new capability
of integrating the whole Disk ][ Controller on a small ASIC--hence the
name Integrated Woz Machine.
What's your opinion of a MFM Floppy Controller then? Here's a link:
http://www.gilanet.com/ohlandl/floppy/82077AA_FloppyControllerDatasheet.pdf
Think this would also an ASIC?
The original 82077 was released in 1988, and was probably mostly ASIC,
though the more complex drive control functions (seeking, recalibrating,
etc.) have a great deal more sequential logic than the IWM (for which
complex functions are performed by the 6502).
Fortunately, there's little relationship between a "standard" FDC and
an IWM or SWIM, since the functionality is partitioned very differently.
Start with the Disk ][ Controller diagram and I think you'll be able to
identify everything.
Good idea. Kind of what I was thinking - that I should be able to identify
some similar items between both devices.
Thanks for the input!
Good luck!
-michael
AppleCrate: An Apple II "blade server"!
Home page: http://members.aol.com/MJMahon/
"The wastebasket is our most important design
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