P21

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Robert Hoeller writes:
>Well, I don't have the manual here, but I think the schematic was quite
>simplified. I did some reverse-engineering on the prototype board two years
>ago, and it did not work exactly the way you described it.
By simplified, do you mean something is missing?  It looks to me like
everything needed is in fact shown, except how you hook up the keyboard.
As far as not being exactly like the prototype board, as long as it can
be run with P21Forth, I'm satisfied.

Jeff writes:
>>I guess my question is, can I just construct a system exactly as the
>>schematic on page 92 shows with NO modifications and have a working
>>system?  Once I accomplish that, I can test most of my questions myself
>>instead of dumping them all on this mailing list.
>Sure.  I didn't get a schematic, and as there may be different versions
>I don't know what you are looking at exactly.  But the schematics I
>have from Moore on Forth Engines are correct for that board.
Ok, I am going to put together a system exactly as the schematic shows.
But there is no indication anywhere in the manual that I can find as
to how a keyboard is hooked up.  I assume it somehow connects to the
74245, as the '245 appears to be the only way to get data into the
system.  I am initially going to be running P21Forth on it, using the
ROM image on your web site for a 128k ROM (image file is slow.rom); I
assume that P21Forth will in fact work with this schematic.
How does it expect a keyboard to be connected to the system?  Dos it
expect 7 bit parallel ASCII data plus a latch pulse from the keyboard
(such as an Apple II keyboard provides), or does it use some kind
of serial input mechanism, or what?

--Andrew