My Homebrew Z80 Microcomputer(calculon80.j89.se) |
My Homebrew Z80 Microcomputer(calculon80.j89.se) |
https://smile.amazon.com/Build-Your-Own-Z80-Computer/dp/0070...
I read that book after Don Lancaster's TTL Cookbook, also published by Howard Sams. That was around 1981, while I was in high school, and I had practically no electronics knowledge before that. Those books were extremely clearly written, and even today provide the foundation of my knowledge of microprocessors and digital logic. I never actually built or programmed a Z80 machine, but the basic knowledge was readily applicable to 6502 and 8088 hardware and software, and even to today's microcontrollers.
Because of the relative simplicity of those systems, I think they are still a good place for anybody to start. Those articles by Steve Ciarcia too. What a genius, at making the microcomputer revolution accessible to hobbyists.
I loaned those books to my best friend, who vanished with them when his family became missionaries, but I don't think he did it out of malice. I'm glad that I can find them online today, just to take me back to those exciting years.
There's a whole book on the ULA - http://www.zxdesign.info/book/theZXSpectrumULA.shtml
2014RC Computerphile video: https://www.youtube.com/watch?v=lU2NKHJygD8
I have a Wyse-55 terminal acting as a display with some ACIA board modifications to allow hardware flow control so it doesn't get overrun. I also have a VFD that'll do 40x15 characters or so, which is narrow for a CP/M system, but I should be able to modify the few programs that'll really make a mess on a narrow screen.
I've got a bunch of pictures on twitter if anyone is interested: https://twitter.com/FeatherOrNot/media
http://cpuville.com/Z80_kit.html
Getting it to work and writing simple programs is really satisfying and totally worth the burns from learning how to solder.
Oh I will. Things just got bogged down over the holidays and everything late last year. My next step is to get everything setup so I can program an EEPROM with my Arduino so I'll have a way to load a program to bootstrap the system. I'm intentionally doing things the hard way though, to maximize my learning. For example, I'm using an Arduino Uno which doesn't have enough digital output pins to represent both the address bus and the data bus for the EEPROM. So instead of just grabbing a Mega out of the parts box, I am using SIPO shift registers to setup a serial -> parallel bus so I can program the EEPROM with fewer wires from the Arduino. No, it isn't efficient, but it'll teach me to use shift registers.
One of my other "next steps" is to just breadboard that Z80 "test circuit" and see if I can get some LED's to blink. I have to get the clock stuff figured out as well...
Like you said, it's a lot of fun. :-)
The Ti86/Ti89 are programmable in both Assembly and BASIC (interpreter on-rom). If you are willing to buy the data cable and fiddle with SDCC (Small-devices C compiler, a "mod" of gcc) you might program them in C as well.
Links:
* Ti86: https://en.wikipedia.org/wiki/TI-86
* Ti89: https://en.wikipedia.org/wiki/TI-89_series
* SDCC: http://sdcc.sourceforge.net/
Also, I saw there is an "ASM" command, but I didn't check if it can assemble stuff or anything.
Is the PCB multi-layered, or two layers? Could you also comment which software did you use to design it? I've used Eagle CAD quite a lot in past and it works great, though I always wished to use KiCAD because it's open source. Thank you!
I will also upload the schematic etc. if anyone wants to have a look or create one their self. However, if anyone wants to build it, it may be a bit expensive due to the high IC count.
Good times
I enjoyed reading about the Calculon/80 and look forward to seeing your next project.
This was the effect I was looking for: https://encrypted-tbn2.gstatic.com/images?q=tbn:ANd9GcQHkdLM...
I used to do C development for the Z80 using one; it translated CP/M syscalls to Linux ones, and would let me run the CP/M version of Hitech C more or less as if it were native. It worked all right. Hitech C was only a K&R C compiler and didn't produce great code, but it was entirely self-hosted.
The script and emulator I used came from here (look for 'Hitech C on Linux'):
http://uzix.sourceforge.net/uzix2.0/index.php?page=down
...but while searching for that I found this other emulator, which looks a bit more maintained:
The text may only be interesting for people building or thinking about building a retro microcomputer.
Five PCBs cost me $250, but they can be made cheaper. Otherwise the price depends a lot on the components. Ceramic ones are very expensive and the whole computer would probably end up at around $300 - $400. For plastic components, the price would be more close to $200.
I think that the 68k will be more fun to write OS and other software for as it is 32-bit, has memory protection, and can run UNIX :-)
I was actually planning to do a ROM emulator with a PIC MCU at first, but ended up using a regular EPROM, SIO/UART and a bootloader to load programs via RS232. When I had a stable program, I burned it to the ROM and continued. This is because when I got started with the "test circuit" I didn't want to go back to the PIC :-D
I'm currently developing my ROM monitor so that I can get CP/M running :-)
http://www.merlintec.com/lsi/merlin2.html
It originally had an Ethernet interface instead of a bus, but since I couldn't get a PC Ethernet board to connect it to I ripped that out and did a simple ISA (actually 8 bit PC bus instead of full ISA) interface. This allowed me to use PC floppy and HD boards as seen in the picture so I could have a "sneakernet" in place of the missing Ethernet.
Edit: Wow, I dug up my original files and realized I did this almost ten years ago: http://www.mrbill.net/byo/
I doubt that I'll ever get around to building one but now, I have the option.