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https://github.com/rricharz/R65

Code and emulator of my home built R65 computer, built around 1978
https://github.com/rricharz/R65

6502 assembler basic emulator history kim-1 microprocessors replica tiny-pascal

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Code and emulator of my home built R65 computer, built around 1978

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README 

        
# R65 - A late seventies computer built with a KIM-1

Assembler and Pascal code of my home built R65 computer, built 1977-1979.



This repository includes the original source files of the programs for

the system. There is also an emulator for the Raspberry Pi in the R65-Emulator

folder. The source files for the R65 programs have been tested on the

emulator.



Below is a screen shot of the R65-emulator front panel.



![Alt text](r65panel.jpg?raw=true "R65 Emulator front panel")



The original program listings are in the folder Original-Program-Listings.



Original Job computer built 1977-1979:

![Alt text](job.jpg?raw=true "job system")



The only picture of the original R65 computer available, made early 1978:

I (left) am demonstrating the R65 computer to Toni Weber (right) from the Swiss toy

store chain Franz Carl Weber. The keyboard (bottom) and the TV screen (in the back)

are visible. The very early reaction time test game played used the led's on the front panel.

 ![Alt text](original.jpg?raw=true "original")



Running ladders written in R65 Pascal:

![Alt text](screen-1.jpg?raw=true "screen-1")



The graphic basic interpreter has just been started:

![Alt text](screen-2.jpg?raw=true "screen-2")



The R65 computer has been built 1977-1979 by myself together with

Rudolf Baumann, who has built his own JOB computer at the same time with similar

hardware. The picture above shows the open JOB computer. The original

R65 computer has not survived. The floppy disks have also not survived.



Hardware specifications of the original R65 Computer:

- 6502 8-bit microprocessor

- 1 MHz clock speed

- 17 kByte, 33 kByte, 49 kByte RAM (expanded 2 times between 1977 an 1979)

- 2 kByte graphics RAM

- 10 kByte ROM

- 40 x 16 char monochrome display

- 224 x 118 dot monochrome graphics display (switchable with char display)

- 2 floppy disk drives. Formatted capacity 199680 bytes each.

- Interfaces: Teletype, RS232, parallel printer, audio tape, golf-ball typewriter, tv



Most of the original 6502 assembler programs have been written by myself

1977 - 1980, some of them based on code snippets found in publications.

They have been modified and improved up to 1982 by Rudolf Baumann

for his hardware. Thanks to him for keeping his hardware (not

functional anymore) and printed program listings up to today. The program

listings have been scanned and digitized 2018 by myself.



The main software includes the original KIM-1 ROM and 4 modules,

which were burned on EPROMS at that time. These modules are:



- A system monitor module, which is executed at startup

- A disk controller module, which handles the access to the floppy drives

- A IO controller module, which handles other IO

- A crt controller module, which handles the display



These 4 modules run in their original version, with the exception of

a few minor bug fixes.



The software also includes an extended disk operating system module (EXDOS),

which has been modified substantially. A number of commands have been added

to the emulator version

of the extended disk operating system module. They allow to import and

export serial data files to and from the Linux operating system and to

"change floppy disks". The emulator emulates 2 floppy drives as in the

original system, but can handle an unlimited number of floppy disks.



The original text editor has not been implemented, because it must be

considered very user unfriendly given todays standards. Instead,

using the "edit" command of EXDOS, the file to edit is automatically

exported to the Linux file system, and the Linux text editor "mousepad"

is called. Once mousepad is quit, the edited file is imported automatically

back into the R65 file system. This happens automatically and very quickly.



Please note that even so the emulator includes the original KIM-1 ROM, it is NOT

a KIM-1 emulator. Only the KIM-1 hardware required for the operation of the

R65 computer system is emulated in the emulator.



The emulator uses a very nice 6502 emulation module written 2011 by

Mike Chambers ([email protected]). The look and feel of the emulated system

is very similar to the original. But everything is much faster.



While the original system used a 8x7 matrix for the character display, I have

decided to use a high resolution font in the emulation to improve readability.



The original R65 computer included a basic interpreter, and an improved Tiny

Pascal compiler. The R65 Pascal system, which was quite powerfull for

a 8-bit microprocessor at that time, and the Basic interpreter have been reconstructed.



The basic floating point subroutines of the R65 Pascal system were published in Dr. Dobbs

Journal, Volume 1, Number 7, August 1976, page 17 by Steve Wozniak.



The original manuals had been written in German only, but the most important part has

been translated to English and is available in the Manuals folder. You should

find everything you need to install and use the emulator on a Raspberry Pi.



The installation instructions are in the manual.



The following Pascal games have currently been reconstructed:

- Reversi

- Pong

- Alien Invasion

- Starship (using an external tek4010 terminal emulator)



No Basic games have survived, but I imported a few Basic games from

http://vintage-basic.net/games.html to test the Basic interpreter.



The contributions in this repository are distributed in the hope that they will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. 

Please report any problems or suggestions for improvements to [email protected]