I use an ancient DOS-based ICE called the Crash Barrier E5. It's effectively a sophisticated ROM emulator, so I use Siemens 'C516 with 6.5 ports to emulate my usual target Winbond with 4.5 ports. I conditional assemble in 'debug' mode, with P0, P2 and P4 re-directed to P5, P4 and P6. The Siemens mpu sits in a pod that plugs into the Winbond's PLCC44 socket, and the connection directs the swapped ports, and handles the ROM interface which is addressed by the E5. The E5 was designed to emulate ALL available 8 and 16-bit micros of its time (1980s - phew).

The E5 talks via the LPT and is very fast, taking ~1sec to download 64kB to the ROM emulator portion. Its drawback is that it's incompatible with anything beyond W98 because of its direct LPT comms. Other drawbacks are its DOS 'window' for debugging, 64kB maximum asm text files - but it has a nice multi-file interface.

It has multiple breakpoints that work by using a second 'shadow' ROM(RAM) that holds breakpoint flags, and its 'monitor' program also resides in the shadow, so on break, it flips program ROM and executes from the shadow. So no lost app ROM.

Reasons I won't convert:

1. Global search cabability across many asm files (needs it with 64k limit, of course).
2. 'Folding' capability within asm file editing, so sections can be folded away for readability.
3. Source file debugging.
4. I'm too old to change and learn a new system.
5. It would take far too long to re-edit all my files.
6. The monitor code is 8051 and I have the sources, so can modify it to my heart's content.
7. Fast assemble, link and download of revised code (<3sec).

Reasons I should change:

1. Make use of an XP OS with USB comms to the ICE.
2. Larger source file limit.
3. I have no spare E5 ICE device - it's full of obsolete FPGAs, and it's likely to die one day. Its designer and manufacturer is away with the fairies - he did offer to let me have the C sources for the PC software - but he never came good.
4. Love to have a more sophisticated debug window.

I have spent some time designing (in my head only) a replacement for the ICE, should it fail. It would have common app ROM(RAM), and two processors. I could then flip between one processor running the target app, and one running monitor, trace and other stuff form it's internal ROM, and accessing the target app ROM as external RAM. Just a pipe dream for lazy moments, and so long as the E5 continues to run, I shall use it.

I'd still be prepared to lay out up to $5000 for a decent replacement for it, however - if I could move seamlessly to it. I use 12-clock devices because there's a fair bit of bit-banging going on in my code, and I can't bare to rewrite that for a single clocker. I did try the Cygnal $99 kit, but couldn't get on with it - or the processor - nothing personal.

Dave