"These aren't the microdrives [droids] you're looking for". These are not the signals you are looking for :) Quite literally, I think the problem is the MDV circuitry generates spurious interrupts. To be honest, I'd be tempted to keep the machine just to show other people it had gesture r...

The 8302 does not have any significant impact on the speed of the whole machine as it's usually accessed in short bursts and, compared to RAM, infrequently. That being said, several pieces of code that access various parts of the 8302 are quite timing critical. Having the 8302 connected to the RAM b...

Interesting that no-one mentioned the biggest difference between HC and LS - power requirements. HC(T) uses power practically only when the signal transitions or there is a resistive load, the latter not being the case when it only drives other HC(T) or CMOS and indeed NMOS circuits like CPU or FPU ...

The 2 resistors connect to -12v supply and each resistor is in turn connected to the raw data inputs to the ULA from the Microdrive. Some kind of negative bias to better address the input threshold switching maybe ? Some time ago I've been told the RAW lines mean Read And Write. When the MDVs are n...

Well, the schematic has more or less been fixed for a while. One thing that has been done is that the original video RAM (first 64k) has been replaced by real dual port RAM, which uncouples CPU and video accesses completely, there is never any contention or slowdown. This also makes it possible to a...

Not silent, just very busy until Oct. 1st - yesterday. Lots of deadlines before most suppliers go to collective holidays.

It seems RAM is limited by compatibility with one of the superbasic compilers (Qliberator?) which used the top 3 bits of the address references to store data about the reference. These need to be 'don't care' for decoding (which also makes it 'fun' to write cache management code...), so only bits 28...

I've never used the PE for longer than it takes to disable it. In that brief time I have observed that it displays a no entry symbol of red on white, and a pointer of two colours, and sometimes a question mark of two colours. I have never been exposed to how they are internally formatted. Even the ...

To make a long story short, the gain in responsiveness will be disappointingly small if at all observable. And it will come at considerable complication to drivers, because under PE the cursor can be more than a 2-bit deep bitmap with the given hardware limitations. The OS updates the cursor under ...

To make a long story short, the gain in responsiveness will be disappointingly small if at all observable. And it will come at considerable complication to drivers, because under PE the cursor can be more than a 2-bit deep bitmap with the given hardware limitations. The OS updates the cursor under v...