*** M E M O R U M ***

If I'm reading the schematic for the RS232 board correctly, Rom decode for the FDX is potentially as much of a problem as the I/O port decode. Whist the DART is compatible with the CFX it looks like the communications part of the board isn't. So I've come up with a GAL design that enables just the D...

I'm guessing the diag ROM merely writes and then reads, which will only detect one type of error. The daig rom writes an XOR of the high and low bytes of the address to each location as it fills the memory, then reads back to check the correct value is present. The early version wrote a fixed patte...

But it works fine when the RS232 board is not fitted? OK, I have found one issue. The machine's stable when in BASIC and running games. The machine boots into the CFX menu fine and as long as you enter BASIC within about 10 seconds everything is fine. If I leave it any longer then the machine will ...

Mmm, that’s odd. Martin, any ideas? The PAL on the RS232 is the usual 14L4. Looking at the pal-assem code for that in the phoenix manual: Pin 14 is the direction pin for the LS245 buffering the data bus Pin 15 enables the DART I/O ports, it's fully decoded so shouldn't clash with the CFX's I/O rang...

That's the reason for the "?" in that post

TI's crazy naming convention

YAY Progress, I'd be looking at the 6116 providing bit 0 of the video memory 6G maybe ?

You can also feed the Y output from J12 pin 2 to a composite monitor or SCART TV. The signal needs to go through a resistor to form a voltage divider as the 9929 outputs a nominal 3v peak voltage, and composite 1v (on SCART at least) 470R is the resistor value I found "on the net". That to...

I'm home now. I've programmed a GAL with the 3 ROM & 64K RAM JEB file from Andy's site, fitted it and the ROM select line is still constantly high. The address lines are active as is the _RD line but no ROM select. What's the logic used to generate the ROM select for ROM A? Maybe I'm missing so...

I don't know if these will help - its a set of WinCUPL files for a replacement MTX500 (or maybe 512) PAL using the ATF16V8

If it IS the 1889, have a word with Andy.

When he put this page together he had spares of that.

http://www.nyangau.org/memotech/parts.htm