Hallo allemaal,
I don't know who also monitors CommodoreOne and/or comp.sys.cbm so I give
you the things I'm working on at the moment.
1) I realised a small board with a 65816, 6526A and some glue-logic capable
of replacing a 6510. Last weekend I put three more ICs on the board and now
I'm capable of using the full 16 MB range on a C64 !!!
The idea is quite simple. First I detect if the 65816 addresses the first 64
KB segment or not using a 688 8-bit comperator and an invertor. The onboard
I/Olines P0..2 are ANDed with the output of the invertor. This simply means
that selecting any other then the first segment puts the C64 in RAM-only
mode ie. I/O and ROMs are disabled.
I already replaced my 4164's with 41256's but I am still have to add a
74LS157 or 257. Notice: _not_ the "A"-version. The idea is that when the
VIC-II needs to access the DRAMs directly, it tristates the 257A's. The
157/257 outputs a (L) which means the first 64 KB segment of the 41256's are
choosen automatically.
You want to use the extra segments for other purposes? All you have to do is
to disable the CAS-signal towards the DRAMs for the wanted range (it can be
any size !!!)
I intend to install 1 MB using four 30-pins SIMMs which means I need some
more glue-logic.
Question: I do have the pinouts of 30-pin SIMM's on paper somewhere :( Has
any body them at hand in E-form, or a URL, please?
2) The day befor I went on hollyday I got the weird idea of connecting an
IDE-HD directly to a 1541 using the three I/O ports of the 6522's: the free
A-one and the two normally used for the diskcontroller. The only thing which
has to be done is writing a new Kernal. Advantage: no complicated
soldering/board needed.
Spin offs: using a 1571, 4040 or 8x50 board as base.
3) In Poland I realised that the same trick can be performed with a C64: use
the keuboard lines as databus and use the userport for the controllines. It
took me 15 minutes soldering and about 45 minutes to make a nice hole in the
side of the case to fit a connector for the HD in.
Next step: writing some simple SW to see if this works at all.
___
/ __|__
/ / |_/ Groetjes, Ruud
\ \__|_\
\___| http://Ruud.C64.org
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