Hi, Rich
I've been unable, so far, to find the doc's I have for ProDos as well as the associated diskettes. I didn't get them with the IIc that, as I may have mentioned, was given to me as a token payment for a piece of PC hardware that the previous owner thought he wanted.
AFAIK, I have all the parts, i.e. the monitor, power supply brick, and the main box. The Monitor has a base into/under which the IIc seems to fit.
The notion of finding and "stealing" the slot decodes from the circuitry on the IIc board is improbable, since the decoding seems to be done in a gate array, and there's no reason to believe that Apple, in all their wisdom, would provide select signals for features not implemented in their design. I believe it would be just as easy to decode the appropriate address(es) myself with a PAL or whatever. In fact it may make sense to use a small CPLD to decode and buffer the proposed external I/O channel, since they're cheap and have sufficient drive current.
My goal, let's not forget, is to find a way to extract useful work from this otherwise not-too-useful system. I'm favoring an I/O channel port, likely containing a few addresses and a data bus, as well as rd*, wr*, irq*, wait* (the 65C02 readily supports that, unlike the NMOS part, which didn't wait on write operations) and I'm simply considering doing this as a more or less universal I/O channel in order to allow others to capitalize on the existence of the channel without limiting the purpose for which it's ultimately used. What makes this so tempting is that there's enough power on the external FDD connector to allow the device to power an external circuit, and there's enough potential, if the job's done neatly, and there is probably sufficient justification for such an effort based on the fact that there isn't an adapter for an external HDD and the like. There are undoubtedly some folks who'd use such a thing, even if they had to build it themselves.
Now, if I ultimately decide to build an extension of the CPU rather than a channel, then I'll put a 50-pin bulkhead connector through the side of the box at the right of the keyboard, near the bottom. If I build a channel adapter, it (the adapter) will probably reside inside and I'll build a bulkhead connector of either 40 or 50 pins in essentially the same place. How many pins will depend somewhat on whether I decide to include power, i.e. +12, +5, -12. Those are available on the external FD connector, though it would be more convenient to have them on the connector. We'll see ...
The idea would be to allow the device to drive a WD1002-05-series HDC. That's a bridge controller which came in several versions but which aren't made any longer. There are plenty of them around, though, and they're easy to program and handle MFM-modulated drives and, in at least one model "standard" 5-1/4" floppy drives as well. I personally like that because it has the potential of allowing one to transfer files between a PC or other machine and the IIc. It would, of course, require software.
What additonal information can you give me about that AZTEC 'C' version that you have? For what machine was it originally developed? How portable is it? Does it run, as-is on a IIc? How about a ][+? Have you any doc's for it with respect to the IIc? I have experience with Aztec's compiler, having used it under CP/M.
That, of course, gives rise to the question of what you want for the compiler you say you've been trying to sell. I routinely use 'C' compilers to lay out the logic in a task for a microcontroller, hence I use 'C' compilers for the 'HC11 and 'HC05/08 series from Motorola and for the 805x series (Intel, et. al.) It might be handy to have one for the 6502, though it would have to support both the NMOS and CMOS devices, and probably would have to support, as a minimum, the ROCKWELL CMOS devices, since I still have a number of them in stock and have MANY of them in the field, occasionally requiring support. I generally write in assembler for the 6502 as well as any other device I use, though the compiler gets me from start to a rough draft of the code I ultimately use. In some cases, where speed and resource utilization isn't critical, I just use what the compiler spits out.
Thanks for the kind offer of your extra Apple][ reference manual, but I did actually find mine, hence, don't kneed yours. I'm considering resurrecting my old ][+, not that I was ever a heavy user of the thing. I only have one drive for it, however, and I may have to snag one at the local thrift store.
It's been a long time since my last look at the Apple I/O map, but, IIRC, there was a 256-byte space mapped into each slot for device specific code (activated, methinks, by the "PR#n" command among others, and normally used to map the on-board EPROM, if there was one, into the common 1.75K-byte memory space common to all slots. Once that was done, the EPROM content could drive the board. Since I only need about 16 locations, I may just chew up a chunk of that common space, if it exists in a IIc in the same way as in the ][+, provided I can find one that was not used by any of the IIc's features. Would you have any specifics on that?
It may be a while before I'm ready to jump on this task, but I may actually get to it this year. My main interest is in making minimalist applications of various microcontrollers, though I do often use the 6502 in cases where I can buy a plurality of identical boards.
A fellow I once knew made quite a handsome lot of $$$ by using VIC-20's which once were very common in thrift stores, and applying them to control and monitoring tasks. Since they had a little memory and an on-board BASIC interpreter, he got pretty good at making them do what people had previously done with a PDP-11/03. I do the same sort of thing from time to time, though I don't run onto multiples of boards as widely available as the VIC-20 once was.
Please let me know what you can about the specific usage of the common page of I/O in the IIc, and about the compiler if you have such details available.
regards,
Uli
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