I have an idea.
And since I am a n00b, and this is the "N00b Questions" section ... well, here goes.
I very soon will receive the LaST 4MB upgrade for my ST, and there is a bridge (which can be pared with a switch) to switch on or off the 4MB expansion (yes, technically, we only disable the addressline, but the effect is the same).
I saw a vid from Adrian Digital Basement where a memory expansion could be disabled by holding the mousebutton during poweron of a Classic Macintosh.
So I got to thinking; that should not be hard at all.
So, here is the idea;
From the mouse button (that's a dedicated pin, pin 6) to the Data port of a D-Type Latch (74LS75, iirc), and from the reset line to the Control port of that latch, that should give a High output on the output if the mouse button was held down during reset, and the inverted output would then be low.
From the inverted output to the base of an NPN transistor, the collector to the address line, and the emitter to the "other side" of the jumper/switch/bridge on the expansion module ...
Would/should this work??? (Maybe it could even be an improvement on the module itself, but let's not get carried away here...)
Now, what I am totally not sure about is what type of transistor or if I have it the correct way round (as in; should I swap C and E), but the idea itself; it's feasable, right? anyone here with logic/electronics/TTL knowledge here to mature this idea?
(If it's stupid, just tell me, I can take it
... )The alternatives are
- creating or finding a hole in the case for a toggle switch
- opening the case everytime the 3 extra megabytes need to be disabled.
Yes, I know, this should not happen very often, or even at all, but 1. it's a challenge and 2. it's neat to have the option to revert to 1 MB temporarily without damaging/opening the case.
R.
