What I like about "single-chippers" is that you have the option of looking at them as programmable logic. They're not all as fast as CPLD's, but they're generally not as costly as a CPLD or FPGA capable of duplicating their function. A Z80 CPU or one of its scions compatible with its instruction set would still require external hardware to provide the interface to read-write memory, then the memory itself, and the decoding for the EPROM, and then the EPROM itself, plus the drivers for anything that requires more than a mA or two. Naturally there are exceptions, most notably those cases where the code needed to solve the prolem is already written for the Z80, but in general, a multi-device solution is not desirable. see additional remarks below, plz. Dick ----- Original Message ----- From: ajp166 <ajp166(a)bellatlantic.netTo: <classiccmp(a)classiccmp.orgSent: Wednesday, November 01, 2000 4:38 PM Subject: Re: Monitor for iSBC 8024 It depends on the nature of the problem you're solving, of course, but generaly, I like to keep it small enough so one has to search for it. If it's on a 4"x5" board, it's too big. If it's in a 1" x 2" board held on the back of the board with some double-stick foam, that's what I like. For an application to be of interest, it's either got to be small enough to be glued to a board in some fashion, or it's got to take its place. There's little room for a Z80, a PROM, a RAM, a PAL, and a clock buffer (assuming one can steal the clock from the host board). Most modern single-chippers have enough poop on their outputs that they don't need buffering, so all you need is the MCU and the clock souce. Dick