Re: apple II roms side not...mousetrap ROM chip

["Bill Garber" <willy46pa@comcast DOT net>]

"Quadrajet1" <quadrajet1@aol.com> wrote in message
20040622043308.10778.00000309@mb-m25.aol.com">news:20040622043308.10778.00000309@mb-m25.aol.com...
: >I thought i'd ask these guestions due to the recent discussion
thread on
: >eproms and roms on the apple // and //e etc
: >
: >I have an exotic product called the "moustrap" chip....for the
//e ..it was
: >made (briefly till apple sued them) by a
: >company that took a switchable ROM (ie. able to hold the old
pre-mousetext
: >char set and also the new mousetext char set) on the same
EPROM chip and
: >switch back and forth between char sets...
: >and it was all incased in a hard plastic with a nice little
label called
: >"mousetrap" w/date (shinny metal foil label whoo who) with a
cable off the
: >end of it and a toggle switch...so back in the day..(1983 or
so)
:
:  I made a number of them mods back in the day,
: right after the enhanced //e came out.  Never
: got sued since I didn't commercialize it, but
: probably made 40-50 sets total.

If all you made was 40-50 sets, then you didn't
even put a dent in Apple's revenue, they shouldn't
care.  :o)

: But what I did was take the 3 ROMs and switch
: from regular //e and enhanced //e. The 2 ROMs
: and the video ROM got switched.  It was so simple
: with an EPROM burner.  Take a 27128 and burn the
: lower half of CD ROM with regular //e code and the
: upper half with enhanced //e. Same with EF ROM and
: the Video ROM, except it used a smaller EPROM.
: Obviously a 65C02 was installed.
:
: All that was needed was to toggle 1 pin high or
: low on each ROM to switch back and forth.  Tie
: all three pins together, all done with 1 wire.
: You would have to reboot once you switched over
: of course.

The easiest way to acomplish this would be to
burn 2 eproms, one with the old video ROM and
one with the newer enhanced video ROM, pull up
the /OE pins stack them and solder them one to
the other and add a switch between the /OE pins.
Push them in the socket and mount the switch.

Another is to burn a double sized eprom and switch
the highest address line between +5v and gnd. So,
in the case of a 2716, you would burn the 2 ROMs
in each half of a 2732 and switch the A11 line on
pin 21 from high to low for upper half and lower
half.

You can also run A11 to AN2 and use softswitches
to select the upper and lower half of the eprom.

Bill @ GarberStreet Enterprizez };-)
Web Site - http://garberstreet.netfirms.com
Email - willy46pa @ comcast DOT net
Change DOT to a dot to contact me



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