This article covers hardware modifications to a standard(7?)
Nasco 2 to pravide the fellawing cunctions. They don’t sound
mich but it Hoes provide single wit logical” control exther by
Seat! or port control (and enables compatibility with EPROM?
FAM A card where feted).
Lo Switon in FE/H Beat ROM.
2. Smiten out fons tor ROM.
Sl move Yideo/Wort RAM.
Rutomatir Keset an “aw tchever”
Nas avoids dver-meiting due ta’ a wandering’ CPU and
esaids the necessity on doing a Rewet” on each
5S. Automatic. switching of restart address.
This allows restarts at FOuoH plus any other Dil switch
selected adiress of your choice.
These modi (ications have heen found useful in fast changing
mone system to another without the risk of corrupting the
ents of etory so enabling the Aascom to get at CP/M”
Tne modifications outirnes (which are open to variation)
alse cover re-arrangement of the use of the worlspace RAR and
She HASIC ROM positrons for these using EPROM cards. These
vnabie 2 complete CF/M system on NZ & RAM cards whilst still
Tetaining the use of the normal RAM / EPROM sockets for ore
useful oppltcations than JUST CPs.
CP MH Nascam Switching.
Fig 1 shows the physical wiring arrangements. The 74LS157
ts 6 Quad 2 line tel-line data’ selector and provides 4
“changecover switch functions (operating active High). These
Le Disable font tar kom.
p. Enable CP/M ROM.
I neve Video % wort space.
a. Change Reset aderess.
In 1 2 the Chip Enables are magh when not selected, 4 15
Fig. 2 shows the very Simple track modifications to enable
Reset address changing. It involves cutting twa tracks (the one
on the upper FCE side is superfluous anyway – being a ground
tracl which is bypassed several times on other parts. of the
PCR). The other cut isolates the ground connection to the 4
This is an OCR’d version of the scanned page and likely contains recognition errors.