Re: SEA files in GSOS

[Jeff Blakeney <CUTjblakeney@sympatico.ca>]

On 09 Sep 2004 23:26:28 GMT, mjmahon@aol.com (Michael J. Mahon) wrote:

>Alistair J Ross wrote:
>
>>  I have a SEA file (it's actually the SHRINKIT extractor), which GSOS is
>>  a text file. I would imagine I just need to alter the file's offset
>>  with a hex editor, but what is the offset and where is it?
>>
>>  I would need to change ASCII -> Executable
>
>I would do it by BLOADing the TXT file (specifying TTXT to ProDOS)
>then BSAVEing it (after prefixing the load address if it isn't already
>there), but I'm sure others have a better way.

This is a good idea, although you missed the CREATE step, but in this
case it isn't quite so straight forward.  GSHK (aka ShrinkIt.GS) v1.1
is 118,119 bytes long so you can BLOAD the entire thing into memory
from Applesoft under ProDOS 8.

You can do it by using a few commands.  The following assumes that the
GSHK self extracting archive is named ShrinkIt1.1.SEA (the filename
for the archive available from A2Central.com's public file library),
currently has a TXT file type and that the file is in the current
PREFIX.  Also note that I haven't actually tested this so it might
need to be tweaked:

RENAME SHRINKIT1.1.SEA, GSHK
CREATE GSHK.SEA, TS16
BLOAD GSHK, A$2000, B$0, L$4000, TTXT
BSAVE GSHK.SEA, A$2000, B$0, L$4000, TS16
BLOAD GSHK, A$2000, B$4000, L$4000, TTXT
BSAVE GSHK.SEA, A$2000, B$4000, L$4000, TS16
BLOAD GSHK, A$2000, B$8000, L$4000, TTXT
BSAVE GSHK.SEA, A$2000, B$8000, L$4000, TS16
BLOAD GSHK, A$2000, B$C000, L$4000, TTXT
BSAVE GSHK.SEA, A$2000, B$C000, L$4000, TS16
BLOAD GSHK, A$2000, B$10000, L$4000, TTXT
BSAVE GSHK.SEA, A$2000, B$10000, L$4000, TS16
BLOAD GSHK, A$2000, B$14000, L$4000, TTXT
BSAVE GSHK.SEA, A$2000, B$14000, L$4000, TS16
BLOAD GSHK, A$2000, B$18000, L$4000, TTXT
BSAVE GSHK.SEA, A$2000, B$18000, L$4000, TS16
BLOAD GSHK, A$2000, B$1C000, L$D67, TTXT
BSAVE GSHK.SEA, A$2000, B$1C000, L$D67, TS16

A generic file type changing program could be written entirely in
Applesoft using this technique but I'll leave that as an exercise for
others.  :-)

-- 
 Jeff Blakeney - Dean of the Apple II University in the
                 Apple II Community on Syndicomm.com
 CUT the obvious from my address if you want to e-mail me