I've been working on upgrading my RC2014 Z80 computer for the past few months, but in a very low-impact-to-my-finances-that-can't-support-it-otherwise way. This post will just go into explaining a few of the upgrades I have in mind,
First of all, my current hardware scheme, the "RC2014/LL MicroLlama" as I call it, is and has been fully functional in its current state, and is emulated well in my emulator.
I started working on a mass-storage solution for the MicroLlama, which I have slightly back-burnered this month so that I could attempt to focus on the 2017-04 RetroChallenge ("The Andy Project"), but I'll likely pick it up again next month, especially with some of the upgrades I now have in my hands, which I will now briefly talk about...
Dr. Scott M. Baker's Bus Supervisor Board
|A ton of chips and a well packed board!|
The short description of this is that it has some I2C I/O Expanders that sit on the entire bus (Data, Address, Control) as well as replaces the system's 7.37 Mhz clock board. This can be used to snoop on the system, read/write IO, read/write RAM, etc... taken one level above that, you can use SMB's python scripts to upload data right into RAM, thus eliminating the need for a ROM module.
People have successfully used this to run 64k RAM-only RC2014 computers, and upload the program ROM from their Raspberry Pi. (Schematic, GitHub link to software)
|It took me about 15 minutes to figure out the orientation of that crystal.|
(Pin 1, the pointy corner, is in the bottom right)
Also, I'm not sure the jumper configuration is correct yet.
I do not really have a RasPi to use for dev work, so my solution is to take a tiny Arduino Leonardo clone ("Micro-SS" like this one), with a cable connecting its I2C lines to the Bus Supervisor Board. Then, I'll make a thin Serial-I2C bit of software and making some desktop tools, perhaps in python to fit with the original from SMB.
|My "proof of concept" for USB-I2C communications.|
Here it's connected to an RGB color sensor.
Obviously, it would also be possible to include a couple of ROM programs directly into the MicroSS, and possibly store a small one in the ATmega 32u4's EEprom as well. Some buttons on the MicroSS could be used for injeting these pre-stored programs. i could even see a program that generates a menu that the arduino can basically farm out to the Z80 to get user responses/menu options, etc.
Additionally, I can make a RC2014 bus - to - pac-man bus adapter, and actually deploy code-in-development directly to the machine from my desktop from the makefile/build scripts. ... This is a dev tool I've wanted for about 20 years now!
Lots of possibilities!
I will put out another blog post and a github link for the supporting software, when I've got this working. (estimated - mid next month)
64k RAM and Pageable ROMI also received this past month the boards for these two official RC2014 boards: the 64k RAM and Pageable ROM. As you can see in the pic, i still need to order quite a bit to make these work. Now that I have the Bus Supervisor board, the Pageable ROM is less interesting to my needs, although I may still adapt my RC2014/LL design to use these pieces instead.
You can see pics of these in the top of this blog post.
The 64k RAM will definitely work well with the Bus Supervisor board, however the Pageable ROM board has definitely taken a bit of a slip down my plate... Until I can get the parts in for the RAM (sockets, etc) I can use my existing unmodified 32k RAM board for the upper segment of memory ($8000-$FFFF) and my slightly modified second 32k RAM board for the lower segment of memory, I just have to manually enable it for read/write.