22 Mar
2004
22 Mar
'04
10:55 a.m.
From: Paul Pennington <paulpenn(a)knology.net>
"Jay West" <jwest(a)classiccmp.org>
said:
> Well, actually, for the ET-3400 my interest isn't so much "collecting"
as
it
> is just plain technical interest. I would be happy with a replica of the
> ETA-3400 to hook up to my ET3400. Is it a complex box to duplicate?
It's pretty much a 6820 PIA, two 2k ROMS (one for Tiny Basic, one for Fantom
II (terminal driven monitor,)) 2x to 8x 2114 RAMS, and a programmed 32x8
ttl ROM (74S188) to handle the address decoding for *all* those chips. The
rest of it is the 5,+12. -12 power supply and the glue between the PIA and
the RS232/TTY & cassette i/o.
There's also a modification back to the et-3400 needed changing the system
clock rate and a few line drivers.
The manauls have the rom code for the Fantom II monitor and even the 74188
but not the Heath/Pittman Tiny Basic.
What do you want to do with it? I don't have
one, but I understand an
ETA-3400 adds a serial port, more memory, Tiny BASIC, and a cassette
interface.
The serial port is easily implemented with a 6850 and a one-chip
RS-232
driver. Adding on more memory should also be one chip
(64K x 8 static
RAM?)
and maybe an EPROM to replace the 1K monitor ROM.
Those are the only
things
I am really interested in doing. Hopefully I can make
it load and store
programs down the serial port to a PC.
As for the cassette port, not interested in going down that road
again!
I'll have to find that Kilobaud article where the dude wires up a floppy
interface to the et-3400...
Has the manual for the ETA-3400 been scanned and
put on a web site
anywhere?
;)
- Mike: dogas(a)bellsouth.net