My experience with the RC2014

[karlab]

Hi All.

 

I just want to share my experience with the rc2014. I have been interested in computers for many years. I got my first computer in very early 1980’s, it was a Casio FP-1100 with a monochrome screen. The computer contained two Z80 CPUs, the main CPU had 64kb RAM and the second Z80 with 48kb RAM was responsible for graphics. The computer also had two 5 ¼ inch floppy disks drives running CP/M and lots of other software. I made software for the computer and did alter the CP/M distribution. I really regret now taking that computer to the dump.

 

For some years now, I have searched the internet for a similar computer which I could play with. There is plenty of emulator software available, but I wanted a hands-on system. I not sure when I first came over the rc2014 system, it must have been 1 year ago. But I hesitated because I didn’t know if I were able to solder the kit. My soldering skills were not the best.

 

So, in January this year took the courage and ordered the Full Monty (classic). Within a few hours after receiving the kit it was fully assembled. I totally messed up the clock board in the process, so I had to scavenge the board and I build a new clock module on a breadboard.

I plugged it into the computer, but it didn’t work. I messed around with various settings and different terminal software but didn’t manage to get it working. I suspected the problem was in the serial I/O module but since I don’t have any fancy equipment I was not able to pinpoint the problem.

I mounted max232 and added RS232 connectivity to the board. That didn’t help either with the communication. So, I gave up. Instead, I bought the CP/M upgrade kit (RAM, ROM, CF) and the dual serial module (SIO/2). After receiving and assembling these modules I had a working system running CP/M. This also confirmed that the backplane, CPU and Clock module from the original kit was OK.

Later I found that the original RAM and ROM modules were also OK, so the problem was with the serial module. I searched the serial module but was not able to find any short circuit or bad connections. I have probably damaged a connector during with my soldering skills.

 

With the working system, I have also gained experience with communication software. Since I am mainly using MacOS (Hackintosh), not all software work equally well. Some mac terminal software does not work at all. If you plan to use RC2014 with a mac, I would definitely recommend Serial (https://www.decisivetactics.com/products/serial/), it’s a paid app but it works. I will also recommend one of these Arduino USB-FTDI modules for communication with the computer. I have over the last months acquired various modules and I can easily put together at least 3 fully working systems.

 

It has always bothered me that I couldn’t get the original kit to work, so I made myself a project to design new PCB boards based on Spencer Owens published schematics. And after a few iterations, I have at last managed to get the system up and running.

 

They say the best way to learn is the to copy the masters, and so I did, but I will probably never be a very good electro engineer, but I have learned a lot through the process.

Also, I have had a great time putting together these kits, trying to get them working and the fault screening.

 

With Regards

 

Karl A.B.

My original rc2014 kit (scavenged), it is a sad view, but I couldn't get it to work.

The resurrection of the Full Monty, now fully working.

[karlab]

Just to follow my previous post:

FYI: Here is an overview of my modules based on the RC2014 classic kit. 

My second project was to try and simplify the classic kit into 3 modules: 1) CPU and Clock, 2) ROM & RAM, 3) Serial and Clock.

I aim was to make an easy to assemble kit with less soldering. In addition, by just replacing one module, the ROM & RAM card with the 512K ROM/RAM module it is possible to go from 32K Basic to full CP/M system. I placed a clock generator on both the CPU and Serial card in the hope that I could run those cards at different speeds, eg. the serial at 7.37Mhz and the CPU at 20Mhz. I have not been able to get this working yet, and I am not sure if it is possible either (maybe someone out there have some tips). But I have been able to separate the clocks so both cards will run with their internal clock, but only at 7.37Mhz. This is still a work in progress.

The 3 modules, from the top; ROM and RAM, Serial and Clock, and CPU and Clock

My third project is to get a case for my rc2014 kit. Someone on the rc2014 group pointed to a blue enclosure (110x180x130mm) on eBay some time back. I went and bought one since I thought it would suit perfectly. All my back-planes were too large for the case, so I designed a new which fit better into the enclosure, but also with room for e.g. USB charger/power supply. This project is also in progress.

 

The Backplane measure 110x140mm

 

 

 

The Blue Box.

[Steve Cousins]

Karl, that's very nice work.

It's great to see what others are doing.

Steve

[karlab]

Thank you Steve

As an update to my 3 module system. I have now successfully boosted the CPU module to 20 Mhz, while running the Serial MC68B50 card at 7.3Mhz.

It also work with the 512ROM/RAM module.

Here are some benchmarks using a prime-number generator (see below for details), with limit 1000.

7.3 Mhz - 5:53 (min:sec)

12 Mhz - 3:37

16 Mhz - 2:43

20 Mhz - 2:10

Z80 SBC By Grant Searle

Cold or warm start (C or W)? C

Memory top? 

Z80 BASIC Ver 4.7b

Copyright (C) 1978 by Microsoft

32382 Bytes free

Ok

10 CLS

20 PRINT "LIMIT";

30 INPUT L

40 FOR N = 3 TO L

50    FOR D = 2 TO (N-1)

60      IF N/D=INT(N/D) THEN GOTO 100

70    NEXT D

80    PRINT N;

90    GOTO 110

100   PRINT ".";

110 NEXT N

120 END

Karl

[Steve Cousins]

And my PC managed it in 0.14 seconds using the Visual Basic 6 code below.

Still, 2m 10s with a 20MHz Z80 is a big improvement on 5m 53s with a 7.3MHz Z80.

Good job we don't do this retro computer stuff for the processing power it offers.

Steve

Private Sub Command1_Click()

10 'Cls

20 'Print "LIMIT";

30 L = 1000: 'INPUT L

35 t = Timer

40 For N = 3 To L

50    For D = 2 To (N - 1)

60      If N / D = Int(N / D) Then GoTo 100

70    Next D

80    Debug.Print N;

90    GoTo 110

100   Debug.Print ".";

110 Next N

112 t = Timer - t

113 Debug.Print: Debug.Print t

120 'End

End Sub

[Jodie R.]

Yes, but Visual Studio took 3h 2m 10s to download, so the Z80 wins again. ;-)

[Conrad Larsen]

Hi Karl

I was just reading your post and sounds very familiar, 1981 had a Casio PB100 then had a zx81 16k ram pack, 48k spectrum with microdrive, BBC master, Amiga A600 then my first pc.

Had also built a hackintosh and used a few years. Now i use a Imac with bootcamp with winx.

And i brought of Tindie a rc2014 mini in 2017/08/09 but only just put it together the other week.

Its my new best thing!

Just received 512k ROM 512k RAM RomWBW and Backplane 5.

  

 

Regards

Conrad

.

[Karl Albert Brokstad]

Very Nice, and congrats with your 512kROM/RAM module.

I am very pleased with my 512KROM/RAM module and together with my CPU/Clock and 68B50/Clock modules and the Flash Drive module is my main setup.

I have 3 different SIO/2 modules, but strangely I prefer the 68B50 module. I found it to be very quick and very robust and I only need 1 serial I/O.

Karl

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Karl Albert Brokstad
Kirkeveien 9B, 5072 Bergen
98843314, 55289014
ka...@brokstad.no