User`s guide

From the usual BASIC prompt, get into the Monitor (e.g. CALL -151) and type in
the following code to turn OFF the ZipGS ...
2000:A9 50 8D 5A C0 8D 5A C0 8D 5A C0 8D 5A C0 8E 5A
2010:C0 0A 8D 5A C0 20 00 BF 65 1D 20 00 00 04 00 00
2020:00 00 00 00
A 2000L should look something like this ...
2000: A9 50 LDA #$50
2002: 8D 5A C0 STA $C05A ; write $50 to $C05A four times to
2005: 8D 5A C0 STA $C05A ; enable access to the ZIP registers
2008: 8D 5A C0 STA $C05A
200B: 8D 5A C0 STA $C05A
200E: 8E 5A C0 STZ $C05A ; write $00 to $C05A to disable ZIP
2011: 0A ASL = SLOW mode
2012: 8D 5A C0 STA $C05A ; write $A0 to stop accessing ZIP
2015: 20 00 BF JSR $BF00 ; Do a ProDOS QUIT call
2018: 65 $65
2019: 1D 20 $201D
201B: 00 00 BRK $00
201D: 04 00 00 00 00 00 00
Use the following commands to save it:
CREATE SLOW,TSYS
BSAVE SLOW,TSYS,A$2000,L$24
To enable the ZipGS (= FAST mode), simply change one byte:
200F:5B
(this changes the STZ $C05A to STZ $C05B)
CREATE FAST,TSYS
BSAVE FAST,TSYS,A$2000,L$24
____________________________
From: William Baguhn
012- Is there some ZipGSx mod that will improve
performance without going to a faster crystal, etc.?
There is; you can do the ZipGSx Split Cache Mod. As your manual explains,
Zip GSX speed comes from having a faster processor which can access code and
data from its high-speed cache RAM. The standard 'GSX has a unified cache, which
means data and code have the possibility of overlapping. If the cache controller
sees a need to bring in a lot of code, it will go to main memory and bring in up
to 64k of code (or 16k in a 16k cache system) and, possibly, overwrite useful
data.