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Re: Computist Issue 30
"Sheldon Simms" <sheldonsimms@yahoo.com> wrote in message
pan.2004.02.27.15.54.53.961467@yahoo.com">news:pan.2004.02.27.15.54.53.961467@yahoo.com...
: I have second sight schematics that I can scan in, but I doubt
: they will be very helpful. The second sight isn't anything
: special, hardware-wise. It's all about the firmware.
I take it, to use as a guide more or less.
: The second sight card consists of a Zilog Z180, an Oak VGA chip
: (don't remember exactly which one, offhand), some memory and
some
: logic that lets the Z180 monitor the Apple II bus: In other
words,
: it is a small Z180 based microcomputer that simply runs an
: Apple II video emulation program, no different than the video
: emulation in a PC-based Apple II emulator.
There are video chips that are basically uCs in themselves.
Not much more is needed. I have several VGA cards from
PCs that are merely 3-4 chips. I believe that hardware wise
I can handle it, but firmware wise I will need lots of help.
: The biggest problems with the Second Sight are:
:
: 1. It is a power hog. It overloads the power supply and can
: cause general system instability if the Apple II power
: supply isn't upgraded.
ICs need much less power today than they used to. Hopefully
there is one that won't bog down the Apple IIs supply.
: 2. It is computationally underpowered. The Z180 can barely
: keep up with the job it has to do. This was recognized
: right from the beginning, but a Z180 was convenient for
: the designers because they were familiar with the chip,
: having used it for the RamFast. (or so I understand; I
: don't have a RamFast myself)
Again, uCs are not what they used to be. Most are good enough
to handle Apple II operations.
: 3. The board was never really completed. I had to send my
: second sight card back to Sequential for hardware and
: firmware upgrades one time, and the firmware, especially,
: was still incomplete. It didn't even emulate all Apple II
: and IIe modes properly.
I wouldn't have released something that wasn't complete or up
to par. You can expect a VGA card from me to work, or don't
expect one. 8o)
: All of that is why I suggested taking the same concept, but
: reimplementing it from scratch, using a modern low-power
: CPU. Only, the CPUs are so fast these days, that you could go
: ahead and toss in 65816 emulation as well and end up with an
: card that acts like an accelerator as well.
That's a smart idea. And if the schematic doesn't work as a guide
then we should look into that, but let's build a Plug'N'Play
card, not
one that would require hacking up the machine. 8o)
P.S., once someone asked me what "eight, Oh, right parentheses"
meant. 8o)
Bill @ GarberStreet Enterprizez };-)
Web Site - http://garberstreet.netfirms.com
Email - willy4SPAM6pa@comXcast.net
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