I’ll be shipping whatever Type-3 Phoebes I still have in stock next week, and after that there will be a short pause until I get the next Phoebe batch. So if you don’t get payment request next week you’ll have to wait until the first week of March, or so.
Same goes for any DocBrowns I haven’t shipped yet. There was a delay with the parts I ordered and now the batch is about 3 weeks behind schedule. On the bright side those will come with 1.5.1 FW that has the Flash corruption issue fixed for good. Though if you had this problem with 1.5.0 and you haven’t recapped your Marty PSU yet, I’d recommend looking into it sooner rather than later. In general these PSU hold up rather well for their age but the electrolytic caps are probably only barely within specs by now.
Speaking of FM Towns, I’ve found some TI docs that nicely explain what external circuitry the 486SLC-class CPUs need to have proper cache flushing support. Considering that replacing the 386 with 486 usualy involves soldering anyway, additional wire or two and an extra 74AC chip wouldn’t really be that much of a problem and it just might simplify a lot of things on the modded system. I need to investigate.
It would be much easier (and cheaper should I mess up) to experiment on a typical PC mobo though, and so I’ve obtained one that looks like it can actually support 486SLC chips natively. But the clock is hardwired to 40MHz for the AMD 386SX that’s on it – and while it’s not terribly difficult to mod it to a different clock speed with external generator, I’m not sure if it’ll work properly with the memory and ISA bus. Chances are those have to be synchronized with the CPU clock.
So, if there’s anyone with a TX486SXLC-040 chip in PQFP-100 package for sale, I’d be very interested in buying it. Or trading for some ODEs if that’s preferable.
UPDATE: Forgot to make a photo of the mobo: