Re: Apple IIc ROM

[Giorgio Morocutti <gmoroc@libero.it>]

On Sun, 27 Jun 2004 20:39:00 GMT, Wayne Stewart <waynes@telus.dotnet>
wrote:

>Giorgio Morocutti wrote:
>> Hallo folks !
>> I have got two Apple IIc: one has matherboard type 612-128F 110V 60Hz
>> USA with ROM 0033B and it works fine with Unidisk drive 3,5". The
>> second has motherboard type 612-128E 220V 50Hz Europe with original
>> ROM 0272A.
>> I picked up a new ROM 0033B for the second IIc, but this crashes with
>> garbage on the screen. :-(((
>> I checked that the first has the IOU chip labelled 344-0021, while the
>> second is 344-0023A; moreover on the first the W1 jumper is OFF and
>> the W2 jumper is ON, on the contrary, on the second W1 is ON and W2 is
>> OFF.
>> Now the question:
>> The crash with ROM 0033B on the second IIc depend on these differences
>> ? (N.B. the new ROM works fine on the first IIc ) 
>
>You've hit on the solution, Giorgio. The firtst ROM, the 0272A is an
>8k ROM which is equivalent to a 2764 EPROM. The other ROM is a 16k
>which is replaceable by a 27128 EPROM.
>So to let the IIc read the 0033B you have to cut the W1 and bridge
>the W2 with solder

Thankyou Wayne !
Now my IIc is working with Unidisk 3,5"  ;-))))

Ciao

Giorgio

Giorgio Morocutti
gmoroc(chiocciola)libero(punto)it

Apple II forever !