- Adding I/O to the KIM-1
- Automated tester
- Building a KIM Clone
- Fix for KIM Clone Single-Step Problem
- KIM Clone I/O Not Receiving Serial Data
- Using KIM Clone I/O Pins

About small SBC systems
SD Card System.
This is a two board system that provides a very inexpensive, flexible, and long-lasting storage option for our KIM Clone , SS-50 based designs, or almost any third party system.
The main board is the Corsham SD Shield. It plugs into an Arduino Mega and provides for insertion of a micro SD card, and also includes a DS3231 based real time clock (RTC). The Arduino does the hard work of providing an interface between the host processor (6502, 6800, 6809, etc) and the SD card and RTC. It connects to the host via a ribbon cable.
The board also contains three LEDs used for status, a RESET switch, a four position DIP switch, a DS3231 RTC, backup battery, and it maintains the Arduino Mega headers so additional shields can be placed on top. Since the source code is available you can add additional drivers for whatever shields you add. Want to add an LCD shield that displays which files are mounted? Just plug in the shield and modify the user interface class in the source code. Only one of the DIP switches has a defined purpose, so the rest are free for you to add your own logic.
The protocol between the host and the SD Card System is completely defined in The Remote Disk Protocol Guide available for download below.
The source for the Arduino Mega is also available for download.
The KIM-1. my first computer. Still have it, and it is still operational.
But I fear to use it for experiments and daily use, it is too valuable for me.
So I invested in KIM-1 clones and replica’s:
– Micro-KIM by Vince Briel
– KIM Clone by Bob Applegate, Corsham Technologies
– MOS KIM-1 Reproduction by Dave Williams
– KIM Uno by Oscar Vermeulen
Each has it advantages. And not all are still for sale.
Corsham is till in business and has an awful KIM Clone, with motherboard, I/O card, experimenters board and SD file system. A real enhanced KIM-1 on real KIM-1 hardware.
The KIM Uno is also available, affordable,now an emulator on an Arduino, soon on ESP32. Fun to have a KIM-1 look and feel.
All are documented on the KIM-1 replica’s and clone page.
KIM replica’s and clones
I have several KIM-1 replica’s or clones, and there are more available.
For me a KIM-1 Replica/clone needs a KIM-1 keypad and LED dispaly, a serial TTY interface, and the original KIM-1 software. Some have a layout close to the KIM-1, others look different, but all are functionally equivalent.
The CPU is of course a 6502 at 1 MHz crystal clock frequency. And they have at least the KIM-1 ROM 6530-002, the keypad/LED/TTY monitor.
Since 6530 RRIOT ICs (the 002 and 003 variant) are not available anymore, the same solution as in the other clones is chosen: a 6532 RIOT with a 2K EEPROM and some logic ICs (3) to get a hardware solution that makes it look exactly the same for the KIM-1 ROM software. The PCB is mostly a new design, not the typical 70ties KIM-1 rounded lines PCB design (except the KIM-1 Nachbau and the accurate reproduction by Eduardo Casino).
All this started with a design by Ruud Baltissen, who found out how the 6530 can be replaced with a 6532.
The result is great: it feels, looks and operates as an original KIM-1 with hex keyboard and LED display and TTY serial interface.
First Book of KIM programs run, All KIM-1 software runs, Microsoft KIM-1 Basic and Microchess run, when additional RAM is connected.
![]() Corsham KIM Clone |
![]() MOS KIM reproduction |
![]() KIM Uno |
![]() Micro-KIM |
![]() PAL-1 a clone, can be expanded with motherboard, second RIOT, RAM, ROM, Cassette interface |
KIM-1 Reproduction by Eduardo Casino
KIM-1 MTU baords by Eduardo Casino
Photos by Peter Offterdinger of ralf02 KIM clones and MTU backplane and K-1013 Visable Memory
MTU backplane and K-1013 Visable Memory display designed by Eduardo Casino
I have two Apple 1 Replica’s, the Vince Briel Replica 1 SE and the Achatz A-ONE.
Both have a 6502 and a 6821 and the original software. Video generation sid one in a affordable modern way, so not real clones.
Fun computers to work with, the first ‘personal computer’ in a very primitive format!
Pages with information on teh Apple 1 and these Replica’s
The PockeTerm is a 4″ X 2.5″ single board terminal that uses a VGA monitor and a PS/2 keyboard for its input and output. Dual serial ports gives the user the option of transferring data to/from a PC while still connected to the host device. This terminal was designed to work with vintage computers but is compatible with most systems including Unix and Linux systems. A low cost color choice terminal that has VT-100 compatible commands for controlling cursor and screen functions. Want to program the propeller microcontroller or install an update to the firmware? No problem, just connect the PockeTerm to your PC, run the Propeller Tools software and you can program it from your PC, no expensive Prop Plug required.
The PockeTerm has a full featured screen with Function key status at the bottom of the screen. Click on the image for a full size photograph of the screenshot.
CTRL-F1 Selects Baud Rate
CTRL-F2 Changes text color of the main display section
CTRL-F3 Turns on/off the 2nd serial port that connects to a PC.
CTRL-F4 Force incoming data to 7 bit ASCII. Strips the 8th bit, required for some systems
CTRL=F5 Change cursor type. Choose from underscore, solid block, or none. Also, choose from blinking or not.
CTRL-F6 Add line-feed to carriage returns
Documents
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Pocketerm Setup and Users Manual 2009 |
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Pocketerm Setup and Users Manual V3 2009 |
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Pocketerm Circuit diagram |
Pocketerm Bill Of Materials | |
Pocketerm Firmware | |
Pocketerm CD |
PS/2 keyboards
I have succesfully assembled the kit, the manual guided me just fine through the steps. Took me just over an hour.
The PockeTerm worked right away. Thanks to mfortuna’s tip, put jumpers in 1&2 and 5&6, and testing is independent of cables and computers to connect.
A standard keyboard with PS/2 worked. What did not work was my mini-USB keyboard (standard PC keyboard without numerical pad, and smaller size, like notebook keyboards) connected via an USB to PS/2 converter. The USB keyboard is ok, works with the PC’s and the Apple 1 kits via the USB-PS/2 dongle. I bought it because the smaller size looks better with the small computers and takes less desk space With the scope I found the PS/2 clock/data line (cant remember which one), to be open, as if nothing connected. So something is missing to make the USB device come alive. I googled around and found this: http://www.parallax.com/Portals/0/Downloads/docs/prod/edu/28060-PS2Adapter-v1.0.pdf
In it I saw a schematic how to connect a Parallax mini PS/2 keyboard, and it was different from the PockeTerm PS/2 interface. It has additional 10k pull-ups connected to the PS/2 clock and data. I soldered in the two 10k’s and the mini keyboard came alive!
Program the Propeller Notes by Vince Briel
The PockeTerm makes a really good development board for learning how to program the Propeller chip. For more information on programming the Propeller,
please visit the Parallax forums here: http://forums.parallax.com/forums/default.aspx?f=25
The above steps will program the Propeller with the code that is now resident on the EEPROM onboard the PockeTerm. Change step 3 to the location of the program you wish to insert onto the PockeTerm.
A collection of articles and projects around the Replica 1.
Rebus
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REBUS Replica 1 Hardware Extensions ACIA, Flash, Apple II sound Ken Wessen |
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Apple II sound circuit |
Replica Quick reference by Jeff Trenter | |
Krusader Ken Wessen’s assember IDE Archive with many variants, sources, versions |
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Krusader 1.2.1 source for use with an ACIA | |
Applesoft Lite archive | |
EWoz extended WOZ monitor with hex file upload | |
Jeff Tranter’s large collection of 6502 articles Micro-KIM, Replica 1, and much more. A real treasure collection, original here! |
EEPROM programmer circuit (as featured on the Multi I/O board)
EEPROM circuit
Here’s a 1 chip EEPROM programmer for somebody wishing to copy their EEPROM or create their own data. In keeping with the replica 1 theme, it is a down and dirty solution requiring few connections. All the connections listed on the EEPROM go to their listed connections. A 74LS00 is all that is required to program an EEPROM.
This attaches to address A000-BFFF and is direct addressing. Simply write to the address to store the data. You should give a slight delay after your write since it takes 200ns to write a byte into an EEPROM. I do a short loop in basic
FOR I=1 TO 2:NEXT I
That does the trick. I tested this circuit out and had 0 errors when writing.
In 2007 Vince Briel tried to get a replica of the Cassette board, as designed by Steve Wozniak, operational. Another example of the genius Steve Wozniak, minimal hardware, 256 byte program. Two revisions, he did not have much luck with this. Reports indicate this has to do with insufficient quality of the power supply lines.
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Original Apple 1 Cassette Interface Manual |
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A real userguide as can be found at the site of San Bergmans |
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Mimeo Cassette Interface and Operations Guide |
Software
Archive with disassembly and source files of the Apple 1 Cassette Interface.
The Multi I/O Board, 2007, gives 2 8 bit bi-directional ports with 4 handshaking lines, a 6522 VIA,, a true RS232 serial port, a 6551 ACIA, with speeds up to 19,200 BAUD, and a 8K EEPROM programmer to store data or programs. There is a socket to add your own Speakjet voice chip that works in conjunction with the serial port to make your Replica 1 or Apple 1 speak!
Software included to let the WOZmon operate over serial.
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Multi I/O board Setup and users Manual |
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multiboard_schematics.pdf |
Three slot expander
Available first in 2006 for the SE and continued to the Plus. One side for the 40 pin connector, the other side a real Apple 1 slot.
Note that sometimes the 40 pin flatcable connection is not reliable and gives CFFA1 I/O errors. A thick extra ground wire between the Replica 1 and the slot expander solves this.
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Slot Expander I board manual |
One slot expander
A single slot expander, one Apple 1 slot, to be placed upon the 40 pin box connector.