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Re: 6502 CPU Schematics
Hello Marcus.
> What's next? The MEGA2 ? ;-)
Humm, not too far off actually! ;-) I had the HAL from the IIe decapsulated
some time back. The idea was to recover the Fuse Map and create a new HAL
using modern means (GAL). Luckily I found a IIe with a PAL. Seems Apple
would use PALs when their normal stock of HALs ran out. I also found that
they never protected these low use PALs either and I was able to read the
Fuse Map (JEDEC) file from it - ending the HAL Decap project.
I then wanted to learn a bit more about the internal structure/security of
PALs (seeing more and more of them on other boards - protected of course)
and sent a copy of the IIe HAL burned to a PAL and GAL to also be decapped.
I was hoping to find the Security Fuse (copy protection) on both these
devices and hopefully find a way to 'reset' it so I could then create copies
of these devices. A 'good' idea, but one which can be very expensive and
time consuming too.
The company that decapped the HAL/PAL/GAL devices also sent me pics of the
die. What I saw was more of a mystery then what I expected. When I saw the
6502 Site my thoughts went back to HAL project and possibly being able to
better understand what I was seeing. Then my mind wondered to the custom
login of the IIgs and other cards like the ZIP GSX and TWII. Being able to
create clones of some of these custom ASICs would be great, although very
time consuming.
Some time back I had repaired a damaged PCT board. The SWIM (or some
crippled version of one) was damaged. Luckily for me the case of the IC had
popped and I could see part the die. I then took out the Dremel and
decapped the rest of the IC. I'll have to post some pics of what I saw, but
what a rats' nest! At least 4 layers and traces running all over the place.
Of course not knowing what some of the structures are doesn't help matters.
Being a MFM and GCR controller I assume this is some kind of a Micro
Controller, but can't say for sure. What I always found amazing about the
SWIM is a 'standard' MFM Floppy Controller is 68 Pins. The SWIM does BOTH
MFM and GCR and is only 44 pins.
So my next step I think would be to start with something 'simple' like the
IWM - being the smallest and easiest to test of all the custom ICs for the
Apple II. I will take a look and see if that IC has anything I can identify
and learn from. If I can produce a working copy of that IC then I'll move
on to something larger. The main idea being that now these custom ICs will
be able to be duplicated using modern custom logic in new designs.
Hopefully it will spur people on to create new hardware that once would have
been almost unthinkable due to the major undertaking of emulating some of
the unknown custom logic and then trying to fully debug it.
--
Henry S. Courbis
www.ReactiveMicro.com
Legacy Hardware and Support - Come take a look at what we have to offer!