newbie building a scratch-built computer

On 8/1/07, Ensor <classiccmp at memory-alpha.org.uk> wrote: Indeed. One of my fellow U Wisconsin employees modifies 1802 code for remote weather stations directly on the hex keypad of his EPROM programmer. He's quite good at it. I got that reaction with a PDP-11 once... our product had a 16-bit "window" register, right above the CSR. The PDP-11/VAX host writes to it and only the MC68K can read it, but whatever the MC68K writes, the PDP-11/VAX reads. We typically did our front-line debugging with a Fluke 9010A plugged into the MC68K socket, to check local memory, checksum ROM, etc. What my supervisor wanted was a program to run on the PDP-11 to constantly read the window, then write the same value to it. That way, the Fluke could write a value to the window, read it back, and if they matched, it demonstrated that most of the bus interface had to be working. He told me he wanted and asked me to get it written that day. I paused for a moment and said back, "L 1000 <cr> D 123737 <cr> D 173402 <cr> D173402 <cr> D 000137 <cr> D 1000 <cr> L 1000 <cr> S <cr>" (or something close to that, from memory). He stared at me, and asked me again to go off and write it and return by the end of the day. I repeated myself. For the third round, he said, "why don't you go off and write that program for me?" I had to tell him firmly, "I just did; go and type this in, verbatim... it's exactly what you asked for". He scowled at me, but finally typed it in, and what I gave him worked the first time. He still didn't believe it. I did a similar thing at the same place years later with the owner - only it was a hex patch on our 68K code. Fortunately, he's an old Geek from MIT, so he didn't question it when I told him to change byte X to value "foo" in a 4 page hex dump and send that to the customer to fix his problem. Java weenies just don't seem to have that depth of understanding these days ;-) -ethan