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

I have surveyed the PCB with a multimeter. I found a few shorts, that I was able to correct. Once I was happy with the board, I installed power leads and the CPLD. Connected power supply and programmer. I am using this programmer. Attempted to program the device: Failed. JTAG error. No device detect...

And since it is the RGB to NTSC/PAL Encoder, do you need it?

If you have a monitor with RGB input, then you could just leave it out.

Martin, On less dense boards I have done that. However you have to bend the wire over to stop it just falling through the hole and the bent over bit adds to the problem of bridging adjacent tracks. That is what failed my 31st Dec attempt. I have been trying to think of a way of evenly spreading the ...

Progress at last 20200126_103449.jpg Lots of steps involved: The layout was revised to ensure that all vias were at least 0.1 inch apart. I created a number of footprints consisting of ovals of different orientations on the upper and lower layer, such as Via_Image.png and placed them over the vias, ...

I have never been sure whether the RAM disk has to be F, or whether it could be G, H, or I.

But to search the drive type table for type 51 would probably work, thanks.

Martin, I was more thinking of detecting a RAM disk from CP/M. Specifically, enabling M576ZVM to warn the user that their RAM disk is about to be clobbered :) I suspect that part of the reason that there is little software making use of more than 64K is that there were very few machines back in the ...

Probably prompted by my struggles with making my own PCBs, Lez as gifted me with three professionally made PCBs: ZX Max 48 Superfo Harlequin 128 Superfo Harlequin +3 Since I am stubborn and determined to build my own design, I thought I would pass at least a couple of these boards on to others. Note...

I suspect that with MTX Basic, the main use of more than 64K would be for large data arrays rather than just for code. If I remember correctly, simple variables are stored in common RAM above 48K and are limited to less than 16K. Arrays (and strings), however, are stored immediately after the Basic ...

In terms of hardware support, it would be possible to produce a custom version for the CFX-II. The speed would be in between that of M576ZVM and CPMVVM. The CFX-II has a silicon disk rather than extra memory for a RAM disk. With the silicon disk it is not possible to directly access individual bytes...

Martin, I am not surprised that you found M576ZVM to be significantly faster (well less slow). The cycle counts given in the earlier post are best case values obtained on MEMU and do not include cycles spent waiting for I/O. Also, they are taken at the start of the program, when M576ZVM is loading t...