Just a few random comments from the designer...
- All my kits are strictly 1980's vintage thru-hole parts.
- No 4-layer; it's all plain old 2-layer, and with bigger traces and spaces than modern PCBs.
-Early kits had the PC compatible parallel port. Current kits have a 6-digit 7-seg display instead (since no one seems to have parallel ports any more).
- Even without an EPROM, a serial loader is only about 30 bytes.
- The 1802 has built-in DMA; so if you add a UART, no software is needed for serial loading.
- Mike Riley's 1802 diskless ELF/OS EPROM has a monitor, debugger, assembler, emulator, BASIC, VTL, FORTH, and lisp; all in just 32k.
- The 1802 is still in production, but mainly in mil-spec (expensive) versions. But they're not hard to find on the surplus market.
-- Lee Hart
The version I bought came with a parallel port, which can be used either for
1) GPIO - so you can control external devices.
or
2) controlling the device, with ELF-LINK.BAS!
Now it looks like Lee's replaced the parallel port with some 7-segment LEDs, which makes it work more like the original ELF (displaying hex instead of binary). But toggling switches does get pretty old, so that parallel port is mighty handy for programming via a computer with persistent storage...
Ok, the manual loaded. Yes, you do have to provide a boot loader for serial:
> Serial I/O needs a program. You can "toggle in" a simple serial loader, or, add an EPROM at U2 with a serial monitor to communicate with a Terminal program…
The parallel port version allowed you to control every switch and read every LED via your host computer, which means you don’t need to toggle anything into RAM manually.
And of course a serial port doesn’t provide any GPIO, so you can only beep a speaker with Q.
All the signals are brought out to J1 at the bottom edge of the front panel card. It appears that you could populate that with a header (since you have the soldering skills to build the kit in the first place), but I'm not sure how easy that would be if the header on the backside (which connects to the CPU board) interferes with soldering. You could at least connect wires.
I would not be surprised if Lee Hart continued to sell the DB25 version. It would depend on demand. I'd ask, he seems very flexible. Maybe he'll continue the development and introduce an FP that had both address and data bus 7-seg LEDs and eliminated the individual LEDs.
Apparently PCs running DOS could control the Membercard via the parallel port, but Windows cannot. I suppose there was a lot of discussion leading up to the change after twelve years, but I'm not yet up to speed on that.
Edit: I forgot to note that you only have to buy a $5 EPROM with the kit. That will include the bootloader, and much more. With that, the card will boot into a monitor.
Looks awesome! I also want modern computers that are more understandable from bottom to top. Like you I feel like hardware simplification has to be one of the first steps. You might be interested in my project, civboot.org and github.com/civboot/fngi
If you scroll down below the ordering section, you'll see an EPROM containing:
"The Diskless Elf/OS ROM by Mike Riley gives you a taste of everything! It has Tiny BASIC, FORTH, Lisp, VTL2, a monitor, simulator, and a mini-editor/assembler. It can also upload/download files in XMODEM format to use your PC as its "disk". All in a single 32k ROM!"
That EPROM can be ordered for $5.
There's a link to Riley's site. The Lisp interpreter I found there is a 2600 line file of fully commented asm.
Edit: this is, after all, a 64K computer kit, usually 32K RAM 32K ROM, but it could be 64K RAM, if you toggle in a minimum bootloader each time, like they did in the old days.
You can do a lot with 64K.
For comparison, the original Arduino Uno had only 2K RAM and was announced about six months after this kit came out.
