Hardware Reference
In-Depth Information
have several chips to write with the same data. Less expensive programmers are available
with only one socket, which is fine for most individual use.
I use and recommend a programmer from a company called Andromeda Research Labs
(
www.arlabs.com
)
.
Custom Programming of PROM Chips
I even used a PROM programmer to reprogram the chip in an 1989 Turbo Trans Am, chan-
ging the factory preset speed and rpm limiters, turbocharger boost, torque converter lockup
points, spark advance, fuel delivery, idle speed, and much more! I also incorporated a switch
boxunderthedashthatenablesmetoswitchfromamongfourdifferentchips,evenwhilethe
vehicle is running. One chip I created I called a “valet chip,” which, when engaged, cuts off
the fuel injectors at 36 miles per hour and restarts them when the vehicle coasts down to 35
mph.AnotherchipIcreatedcutsofffueltotheenginealtogether,whichIengageforsecurity
purposes when the vehicle is parked. If you are interested in such a chip-switching device or
custom chips for your Turbo Trans Am or Buick Grand National, I recommend you contact
Casper's Electronics (
www.casperselectronics.com
)
.
EPROM
OnevariationofthePROMthathasbeenpopularistheEPROM.AnEPROMisaPROM
thatiserasable.AnEPROMchipcanbeeasilyrecognizedbytheclearquartzcrystalwin-
dow set in the chip package directly over the die (see
Figure 5.4
). You can actually see
the die through the window! EPROMs have the same 27xxxx part-numbering scheme as
thestandardPROM,andtheyarefunctionallyandphysicallyidenticalexceptfortheclear
quartz window above the die.
Figure 5.4
An EPROM showing the quartz window for ultraviolet erasing.
