EV IEEE Board
EV Computing writes: “Our IEEE card uses port FF hex for page mode switching
as well as the ports 34-3F as correctly shown. We apologise for this error on
Mike Hessey of Lucas Logic writes: “Please find attached a list of the I/O
ports currently being used by Lucas Nascom. Other future products may use port
numbers mentioned on this list. All these boards can be used with all other
Nascom 1 – ports 0-2 & 4-7. No alternative ports. Uses NASIO. Requires
buffering for connection to Nasbus.
Nascom 2/3 – ports 0-2 & 4-7. No alternative ports. NASIO is not used. No
Input/Output Board – 8-B & 10-12 & 14-1F. Alternative ports: All addresses can
be selected via on-board links. Potentially could access any I/O address via
A7-A0. Second board would normally use addresses up to 2F. Requires interrupt
FDC Board – E0-E3. Selectable to 20-23, 40-43 etc.
– B0-B2. Screen memory is paged in automatically by graphics support
software, normally at 8000 (link selectable). Requires use of RAM disable.
– Port FF output used for page selection.”
Well, Mike, I hate to contradict you (honest) but:
a) Surely NASIO is used on N2 & N3 when there is external I/O? After all,
there’s a switch on the PCB to select between NASIO internal/external.
b) The I/O board circuit diagram I saw implies 8-B & 10-1F are decoded.
c) The FDC circuit diagram I saw implies E0-E4 R/W and E5 R/O, and so does the
Sound and FDC
Mr. A. Brown writes: “I wish to supply the following information–
|Easicomp Sound Board –||Port||2,||write||only,||port||3||read/write,||or|
Lucas Nascom FDC Board – E0-E5. I/O provided.”
Animation Graphics Board
Mr N. Crook writes: “The R & EW Animation Graphics board for the Nascom
(Nasbus) (R&EW Jan. ’83) uses ports 08-1DH inclusive as far as I can tell from
the article. Although I do not have one I know several people at NASTUG who
are building then.
“Your ports map is coming in useful for me since I have finally started
the design of my own I/O board (blow the dust off the prototyping board!).”
Isn’t this the same board mentioned by Mr Moyle above? If so then there is a
contradiction in the port requirements for this board between their letters.
Oh well, if anyone else has any more corrections to make, or new boards to add
then please write in. I hope that I will have sufficient accurate information
by the time the
Nov-Dec ’83 issue
goes to print to provide a “this is a state-of-the-art
port map of the 80-BUS at the end of 1983.” For some reason I had
imagined that this would be a simple job, but with some people being unwilling
to supply any information and others supplying contradictory information I am
beginning to think that I let myself in for somewhat more than I expected!
Never mind, I won’t need to bother after 31/12/83 as it will be 1984 and Big
Brother will be watching over everyone for me.