General > General Technical Chat
Show us your unfinished project!
pqass:
Bring out yer dead..... Bring out yer dead.....
In '85 I really wanted my own bare metal micro. This 8085 card was the start (and end) of that dream. I got an XT clone the following year.
I didn't breadboard any part of it; just direct to layout. I used rub-on transfers and tape, etched it myself (naturally), and used a Weller gun to stick it together. Someday I'll get around to buying an 8085 for it.
daqq:
A hardware based brainfuck* language interpreter. Did it some 12 years ago when I didn't have that good an understanding of logic design. Worked well in the simulation, in retrospect the flaws were obvious.
* - https://en.wikipedia.org/wiki/Brainfuck
capt bullshot:
A data collection hub intended to replace a lot of separate boards in my home data aquisition system.
Does quite a lot of temperature sensors of various types (Pt 1000, NTC, KTY, SHT21), voltage, current and digital I/O.
Built this about 10 or 12 years ago, and
guess what: though works indeed, the old boards are still in place |O
capt bullshot:
This one was intended as a central "networking" hub for the same system.
It has 4 * CAN bus, 2 * RS485 and RS232 plus some supply switching and overload protection.
It's working but never found its way into the system. Today there's a somewhat more sophisticated version that does Ethernet too in place of this one.
MarkL:
Here is my unfinished Z280 board than ran at 20MHz and had 2MB of memory. I only got so far as running a small debug monitor from EPROM, which was enough to test the memory design (it worked fine). The blank areas were for two dual-UARTs (DARTs), a floppy disk controller, a SCSI disk controller, and an RTC. It all just barely fit.
The Z280 was backwards compatible with the 8080A and Z80A instruction set, so eventually I could run CPM and legacy applications on it. But the real attraction was that the Z280 was meant to be multi-user and multi-process, and had a full MMU to support it. My longer term plan was to get UZI280 running on it, which a version of Unix.
I had all the parts to finish it. But after a few years on and off working on this, I finally gave up around 1995 in favor of just buying an x86 machine and running Slackware Linux. At the time I also found a Z80A emulator that ran on Linux at about 50x a real Z80A to support the legacy applications. In the CPU market, the Z280 was a flop and was either discontinued by Zilog or at least the writing was on the wall, I don't recall which. There was just no point in investing more time. RIP Z280 board.
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