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Eric LaForest wrote:
> Love to see those.
>
> Looks like a neat design. I always wanted to homebrew a wearable around a
> small embedded 386/486 which would run Linux to provide a programmable
> interface to a small army of DSPs. :) I'd get mail and all that as well
> as high speed, hard real-time Real-World signal processing. But I got a
> NetWinder...so all I have to do is to get some DSPs plugged into it and I'm
> rolling...
>
> As much as commercial solutions are good, homebrewing has advantages...has
> anyone else homebrewed (if only on paper) something neat?
Alrighty then. The fellow whose scanner I use may have left it locked
in his dorm room over christmas, but hopefully not. I suppose I'll post
large attachments of scanned legal pad soon...
The reason I gave up was because I couldn't figure out how to write a
dynamic memory allocation routine... Any help here would be helpful...
I was unable to dredge anything useful out of the 2.0.36 kalloc routine,
as it is beyond my understanding.
But here is a bit more detailed description, in case your mouth is
watering (keep in mind that there may be inherent flaws in the design):
The thing was designed to function as a PDA sort of thing, with a DB25
expansion port for adding an HMD, keyboard, and hotsync-type of thing.
Looking at my schematics, I see that the keyboard interface was never
scribbled down, but I was planning on using a PIO to scan a key-matrix.
Not that big a deal. I pulled several from out-of-service VIC-20s,
though they are of the 680x line.
The primary (ie built-in) display was designed around a 480x128 graphic
LCD and an HD61830 LCD controller (the LCD is $8 from www.allcorp.com).
The schematic for that is on the back of a placemat around here
somewhere, so I'll either have to find it or (more likely) redraw it.
That LCD comes with an enclosure, too, which was going to house the rest
of the circuitry, too. Only problem is that the 61830 only comes as a
non-standard sized QFP (ie can't get a QFP-to-DIP adaptor for it)
I was mistaken about 1Mb of RAM, the chip in my drawing is a 128Kx8
Sram, but it could be easily replaced by up to 4Mb (as I recall I was
using a 1Mb chip until I found the 128K chip for a very low price).
The memory map:
< 0x0000 - 0x7FFF > ROM (32K)
< 0x8000 - 0xBFFF > Non-Paged RAM (16K)
< 0xC000 - 0xFFFF > Paged RAM (16K)
The IO map:
< 0x0 > Bank switcher. The 128K ram gives you 7 pages
of banked RAM. 1 through <n> here switch
to whatever bank, where <n> is the last bank.
Writing a zero causes the non-paged area to
be mirrored in the paged area (which may or
may not be useful). This location can also
be read from, returning the current bank.
< 0x1 > Display0
< 0x2 > Display1- These are for the LCD controller.
< 0x3 > KB- the PIO attached to the keyboard.
< 0x4 - 0x7 > Unused. Perhaps internal expansion later?
< 0x8 - 0xF > These lines come out to the expansion port.
Hmmm... If I hooked a 555 to the IRQ line of the Z80, perhaps it could
run a port of Linux8086. I still want to port it to the Apple2...
Please comment profusely(sp?), as I do plan to build this machine
sometime, or at least a variant of it... Say, no mechanical componets
(besides keyboard)... I'll bet this would make a decent car computer,
though a TNC and a dumb-terminal would work ok, too (my MFJ-1270B has a
Z80 in it... :).
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