APPLIED ENGINEERING TransWarp - Manual (Page 8)

Software Control Programmers can also control TransWarp from within their programs by writing a
specific value to a certain memory location. This location, expressed in
hexadecimal notation, is $C074, and in decimal notation, 49268 (-16268 Integer
BASIC complement). The valid values which can be written to this location are 0,
1, or 3. A zero enables the maximum hardware default speed. A one will cause the
TransWarp card to run at 1 MHz. Writing a three will disable the TransWarp card
completely and pass processing control to the Apple’s processor until the
TransWarp is again activated by cold-booting the system. The following example
Applesoft BASIC program line will slow the TransWarp to the 1 MHz clock rate.
]10 POKE 49268,1
Accesses to the Apple’s RAM and ROM are restricted to the Apple’s clock rate of
1 MHz; therefore, on power-up, TransWarp loads the Apple’s ROM into its RAM,
and uses the rest of its RAM to emulate most of the Apple’s main and auxiliary
memory, running at accelerated speed. The Apple’s memory is used only for
video display of text and graphics, which requires the 1 MHz rate. This can cause
some video- intensive programs to run slightly slower than full TransWarp speed.
TransWarp does not use the memory cache-ing technique to increase
processing speed. All processing in main and auxiliary memory is accelerated.
This is a great advantage to users of memory expansion cards which install in the
Apple //e’s Auxiliary Slot, such as Applied Engineering’s RamWorks and
RamWorks II cards. All accesses to these cards are at TransWarp’s accelerated
speed. Using RamDrive software to use the accelerated extended memory as an
emulated disk drive, disk-access-intensive programs loaded to and executed
from a RamDrive will run appreciably faster.
CP/M Software Z-80 cards which have their own memory and do not use the Apple’s direct
memory access (DMA) bus, will function (at normal speed) with the TransWarp
card active. Since processing for the CP/M software is being done by the Z-80,
TransWarp’s 65C02 will not accelerate CP/M programs.
Some Z-80 cards use the Apple’s DMA bus to access the Apple’s memory. The
TransWarp card must be deactivated before running CP/M software on Z-80 cards
which do use the DMA bus. TransWarp can be deactivated during a CP/M cold
boot by depressing the ESC key during power-up. (See the section entitled
“Hardware Control.”)
TransWarp
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