RC2014 – SandsSpot

2025-09-102025-09-10

Added a small case to the RC2014

I received the “Front Panel” and “Rear Panel” Kits for my RC2014 Z80 Computer. These panels are specifically designed for the Blue Box 110x250x190 mm project case, which I had purchased even before I got the initial kit to create the RC2014. I spent the last few days soldering and assembling the panels.

Showing "LCD Driver Module" and "Front Panel I/O" module. — The left side is the LCD Driver Module and and LCD Display and the right side is the Front Panel I/O module and the actual Panel for the front of the case.

You can see little tabs poking up through the back of the LCD panel. Under the little interface board that converts the 2×20 ribbon connector to the 16 pin the module needs is a tab that poked up into the pins of the little interface. It caused problems and I had to clip off that one tab. The Front I/O panel was also a problem, I soldered its ribbon cable header to the wrong side of the board, I had to desolder the header and flip it around behind the front panel so the ribbon cable could connect. My reading skills must be slipping. Though I don’t think the instructions mentioned the tabs on the LCD Display poking into the pins of the cable header.

There was a good bit of head scratching before I fixed those problems. But in the end, the front panel I/O and LCD Display are working well.

Showing RC2014 Front Panel assembled and attached to the case.

Showing Detail inside BlueBox case with RC2014 mounted inside, ribbon cables connecting to the front panel

The switches on the Front Panel I/O control the boot up. There are several choices for how to boot.

First is the Small Computer Monitor, a program that allows direct access to the CPU registers and memory.
Second is a version of Microsoft BASIC for 8080 (and Z80) microprocessors. This would be similar to how many 1970s and 80s computers would boot straight into the BASIC language interpreter (Such as the Commodore 64).
Third Boot option is a FORTH Language Interpreter. I have no idea how to use FORTH, at least at the moment.
The Fourth Boot option is a simple game called 2048.
The Fifth boot option is CP/M 2.2, Digital Research’s famed operating system for personal computers of the late 1970s and into the 1980s and that a version of was offered to IBM for the IBM PC. But Digital Research didn’t like the restrictions IBM wanted (and which Microsoft found a way around when the licensed MS-DOS to IBM).
The Sixth option is Z-System, an enhanced version of CP/M for the Z80 CPU (and the one I use the most).
The Seventh is a “Net Boot” which won’t work since I don’t have the RC2014 on the network.
And the final (eighth) front panel option is a User ROM boot, but I haven’t put in a User ROM so no booting from it either.

The Front panel also has an option to boot from the hard drive (in my case a Compact Flash drive like I have in my Canon EOS DSLR). There are 5 “slices” to boot from the current hard drive.

Slice 2.0 boots CP/M-80 v2.2
Slice 2.1 boots ZSDOS v1.1
Slice 2.2 boots ZSDOS v1.1 (yup, I’m wondering if I messed something up)
Slice 2.3 boots CP/M-80 v3.0 with Banked Memory
Slice 2.4 boots ZPM3 with Banked Memory (compatible with CP/M+)

I made a second Compact Flash (CF) for learning how to customize the system. I’m still using the original Compact Flash drive that came with the kit, though. The second CF drive has several Infocom Games, like Zork, or Hitchhhiker’s Guide to the Galaxy, the classic Colossal Cave Adventure, and a few others. I also have HiTech-C and z80ASM programming tools, WordStar and ZDE, and stuff I’ve already forgotten.

The install of the Rear Panel Kit was simple. I got the blank version, it has blank cover for the holes where cables and connectors will eventually go. I’ll get those as I need them. Things like the FDTI adapter, and audio ports, maybe a video port, and so on.

Next up? I think a sound card, probably this one Why-Em-Ulator.

2025-07-312025-09-10

RC2014 Project Update – Does it work?

First things first

So first, before revealing if the thing works or needs more work, the first part of the update is that I finished the Backplane Pro. The Backplane Pro has 12 40-pin slots for the modules. It took a while to solder in 12 40-pin headers, 4 20-pin extended headers (the number of extended headers depends on how many extended bus modules you’re using. I have three at the moment, but I put in four), and a number of other small parts, a couple resisters, a power switch, power LED, a power jack, a reset button, and so on. I didn’t count all the solder points, At least 580 solders. I might have mentioned I’m a slow solderer; it took me most of the day.

Then I buzzed it out (using continuity testing of my Multi-Meter Oscilloscope, a ZOYI ZT-703S). I made sure all the header points had the signal they should, and didn’t have bleed over they shouldn’t. That took a while too. When I finished that, and did not find problems, I applied 5 volts to the power jack and checked the power LED did light, and the +5 and GND points all showed the power.

Fairly sure the backplane was good I went about checking the module circuit boards. I put them one at a time in a slot on the backplane and checked that power routed cleanly to the points in the sockets (without the integrated circuits plugged in). Everything looked good there too.

So I plugged all the ICs into their respective modules. I did the Z80 CPU first (only one IC, the actual Z80 CPU) on that module). Then the SIO/2 board, and so on. The only board I didn’t get completed is the Real Time Clock module – I don’t have a spare 2032 Coin Cell for it. Then I put the extended bus cards, the Z80 CPU, the Z80 SIO/2 board, and the DUAL Clock in the first three extended bus slots (Slots 5, 6, and 7). The ROM/RAM Memory module is in Slot 8, an extended bus slot but that board doesn’t need the extended bus. Finally I put the Compact Flash module in slot 4, a standard bus slot. I left the Real Time Clock out for the moment, given it doesn’t have it ‘s backup battery yet.

Finallly, I attached the FTDI cable to my computer and into the RC2014. I had to find the com port Windows assigned to it – which took it a while. It’s Com5. I fired up putty terminal software and configured a session to Com5 at 115200 bps and pressed reset on the RC2014. I got my first boot up results:

First Power Up screen for RC2014 — RC2014 Power up Boot – SUCCESS!!! It WORKS

SUCCESS!!! IT’S ALIVE

I was very happy, especially given the trouble the silver based solder gave me to start with (and two destroyed modules that I had to repurchase).

I did put the Real Time Clock (RTC) onto the board for the “photo op” where you can see the assembled system all together. But I didn’t power it up at that point (I thought about it so you could see the glowing power lights and such.

While I had the system powered up, I launched the Z-System operating system (not the IBM Mainframe Z-System OS…) and explored the compact flash. I also tried out Microsoft Basic and made it print:

Hello,World! RC2014 - is ALIVE!!!!!! John Sandlin 250731

I meant to make it print the full year, 20250731, but made a typo and didn’t fix it the right way. The backspace key doesn’t work correctly in Basic.

What’s Next

There are a number of things I want to do still. I want to get the RC2014 Front Panel Kit (and a back panel kit too), a Sound Module that uses a vintage sound module that were popular with the MSX Z80 based computers, and a video / keyboard interface. The Front Panel Kit gives it a proper vintage Kit Computer look. My first computer was a HeathKit H89, which I built while studying MicroComputers through an NTS training course, but the Front Panel is even more primitive than the H89.

I might also want to see about making the RC2014 work with MSX software. That’s down the road a bit though.

2025-07-302025-09-10

Project RC2014 Continues, after a short delay

I started the project using the silver based solder to try to keep it all RoHS. But the Silver Solder and me soldering wasn’t working out. I damaged to two of the project boards, The Serial IO and the Dual Clock boards. Silver Solder requires higher temperatures, I’m not the fastest solderer, and I melted a couple sockets so that pins fell out, and then I couldn’t get the silver solder to desolder and basically destroyed the boards. I had to order replacement PCBs and replacement components.

Now though, I have six RC2014 modules soldered up and just have the backplane left to go.

Six Modules done

The six modules, starting top left and ending bottom right, are:

Top Row:

Dual Clock Module

The Dual Clock Module is an Enhanced Bus card (it has two rows of pins to the backplane). This is the system conductor, keeping the clock pulses that the CPU needs to execute the instructions in coordination with all the other components. This clock has to talk to all the other modules to keep them in Sync.

Compact Flash Storage Module

The Compact Flash Storage Module will hold all the software to run on the RC2014 computer. Back in the day computers like this might have used Paper Tape (like the Altair), or cassette audio tapes (like a Commodore Pet (which also later used floppy disks), or Floppy Disks (like many CP/M machines like mine will be), and maybe even a smallish hard disk drive. The Compact flash takes the place of the hard drive and can have a reasonably large capacity (if you can imagine 64 MB being reasonable), well compared to the 5 MB drives of the time.

Middle Row:

Z80 SIO/2 Serial Module

The Z80 SIO/2 Serial Module allows the Zilog Z80 CPU to talk to the outside world – like the User. It’s an old reference but the movie TRON, this would be the I/O Towers programs used to communicate with the Users. Back in the day when CP/M computers were The Big Deal, the SIO would connect to a serial terminal, like a DEC VT100, or to a keyboard and monitor if that computer had one, like modern computers and laptops do.

Real Time Clock Module

The Real Time Clock Module is purely optional and many CP/M computers in the early 1980s did not have one, you had to tell it the date and time each time you booted it up. I can have a script run in CP/M that reads the current date and time when the computer boots up. It’s handy to have your files time stamped.

Bottom Row:

Z80 CPU Module

The Z80 CPU Module is the brain of the system. The Zilog Z80 was an improvement over the Intel 8080 and was very popular in many CP/M computers. The Z80 is an 8-bit computer CPU that often came with incredibly small amounts of memory. 16K was common, along with 32K, 48K and even 64K. 64K was the most an 8 bit computer could typically address with a 16 bit address bus without resorting to “Bank Swapping.” A screen on these old computers could hold 80 text characters each on 25 lines. So imagine 8 of these screen pages, and that’s the 16K. All your software had to run in that memory, including the screen buffer (those 80×25 character lines of text), the operating system, the application (like Word Star, a popular word processor back then) and all your data. But memory was crazy expensive, so you did what you could in as little as you could afford. Until very recently, Zilog was still making the original 40 Pin DIP Z80 CPUs (albeit in slightly faster clock speeds). Zilog discontinuing the Z80 prompted me to do this project before the chips are all gone.

512K ROM / 512K RAM Memory Module

The 512K ROM / 512K RAM Memory Module takes advantage of Bank Switching to let the RC2014 address more than64K of memory. This is where the computer holds all the information it’s working on and with, the instructions in the programs it’s running, and anything it needs to complete the tasks it’s working on.

NEXT UP:

Tomorrow I’ll start work on the RC2014 Backplane Pro. This is the backbone of the computer, and also distributes power and facilitates communication between the module. Then the troubleshooting begins!

2025-07-062025-09-10

Project RC2014 is started

I have my first board for the RC2014 Z80 computer put together. This was a simple board, just a socket, four resisters, 1 capacitor, and a right angle header. A lot of small solders, though. Once I have a chance to validate the solders are good and I have the backplane wired, I will put the CPU in that socket. I just want to validate the power and ground are going to the right pins first. So I have a good deal of soldering to do before I get there.

I’ll probably work on the Dual Clock Card tomorrow. Every CPU needs a good clock, or two.