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KIM-1 6530 Replacement board

A very common problem with maintaining 40 year old computer systems is that some of the parts have not been made for many decades, such as the two 6530 chips on the KIM-1. Each contains several timers, 64 bytes of RAM, multiple parallel I/O ports and 1K of mask programmed ROM containing the KIM-1 monitor program. To make things even more complicated, each 6530 is mask programmed with a number of configuration options such as which interface pins and address lines select which internal devices.

Many people, Bob included, have at least one KIM-1 in their collections with a non-functioning 6530. Depending on what failed, the KIM might be quite usable, completely unusable, or someplace in between. For these people, there was little chance of ever fixing the problem because the two 6530s in the KIM are unavailable anywhere… not even on eBay! In an effort to fix his own KIM, Bob borrowed work of other people and developed a small board that can replace either 6530 on a KIM-1.
Basically this emulates the functionality of the non-functioning 6530 by using the I/O ports, RAM, and timers from the 6532 chip, and then having an external EEPROM hold the code that was in the ROM of the original chip.

The board replaced U2 (6530-002) on Bob’s KIM and produces a fully functional system again. This is a prototype board (strange board color) but is identical to the production version otherwise.

For full documentation, schematics, design files, Gerbers, EAGLE CAD files and other technical data please also see Bob’s development notes.

The assembled version is the quickest way, and the easiest. Just set the three jumpers to either U2 or U3 to indicate which chip you’re replacing, remove the old 6530, then plug in this board. Bob strongly suggest saving the original 6530 in case you ever decide to sell your KIM to a museum as a static display.

KIM-1 6530 Replacement board manual
6530 replacement development notes
Schematic KIM-1 6530 replacement
kim-1 6530 design: gerbers, eagle, KIM ROM

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KIM-1 I/O board


The KIM-1 Application connector has a lot of useful signals on it and our expansion board makes them easily usable, as well as providing an RS-232 interface to the KIM’s serial port. The KIM has a 20 ma loop interface because that was the standard used by mechanical teletypes commonly used as terminals in the early days of the microcomputer revolution. Now we all have RS-232 ports on our computers and our I/O board allows a modern computer to connect to the KIM.
The expander plugs into the KIM’s Application connector. The lower left hand side of the board has a DB-9 connector that mates with a standard cable to a PC serial port.
Just above the serial connector are two standard 1/8″ inch audio connectors for a tape player; some people still like saving data to tape, just like in the old days. If both cables are out then the audio in/out lines are connected; this is perfect for running PLL adjustment programs. There is a jumper to select whether to use the audio high or low connections.
Above the audio connectors is the power connector with connections for +5, +12 (only needed if the cassette interface is used) and Ground. A filter capacitor is present to keep the voltages smoothed out.
Two of the best additions to this board are the POWER LED and KBD/TTY switch. A few people, myself included, have almost pulled board or made other changes while power was on. The handy LED provides an indication that 5 volts is present.
If you’re switching back and forth between the normal KIM KBD operation and using an external TTY device, there is now a small switch located on the board that is clearly labeled as to which position is for KBD and which is TTY.
There are various connectors and a set of switches provided for feeding the K1-K4 lines to an external memory board, such as our 4K or 60K memory boards. Each K* signal is individually selected, so if you have peripherals in any of the K1-K4 banks, you can disable any of those signals from going to the external board.
All of the remaining I/O lines are brought to a header for expansion.

Manual KIM-1 I/O board Rev C

Rev B 2006

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KIM-1 Multifunction board

A large multifunction (I/O and RAM combined) board, from 2017) and a Motherboard

This board combines several existing boards into one, and puts it into a form factor meant for those who have legacy motherboards such as the MTU K-1005, or any other motherboard that brings the raw Application and Expansion connectors to third party boards. It can also be used with the Corsham Technologies KIM Motherboard

Manual KIM-1 Multifunction board
KIM-1 Motherboard Manual

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44 Pin Extender Board

This handy-dandy board was created at the request of a customer and also to fill some needs on our workbench. One side has a 22/44 connector ready to plug into your KIM or any other computer with 22/44 edge connections on .156″ centers. On the other side are the same pins for you to plug another board into.

In the middle is the cool stuff. All pins brought to a .1″ center header, and each is labeled so you won’t forget that some letters aren’t used??

There are a couple of good uses for this extender. First, you can easily probe any signal between the KIM and add-on board. Nice. The other big plus is that it saves wear and tear on the edge connectors of the KIMs in our lab. They are almost 40 years old, so we try to be gentle on them.

An older version in use in our workshop…

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KIM-1 4k Memory board

A very simple board to add 4K RAM to lower address space ($0400-$13F

Manual KIM-1 4K RAM board
Schematic 4k RAM Board
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SYM AIM 60K RAM board

Basic features of the board include:

Can be used on either a SYM or an AIM.
Memory selectable on 4K boundaries covering the entire 64K address space. Not all blocks can be RAM, as the SYM-1 already has up to 4K of RAM on-board, there are multiple ROM sockets, and I/O.
The top $80 bytes are not available; that area is reserved by the SYM-1.
Can allow space for BASIC or other software in ROM. My system has an 8K BASIC ROM so I did not place RAM at C000-DFFF.
Can be ordered as a bare board, a kit, or fully assembled and tested. The bare board is just that… no components. The kit includes all components and you will need to solder the parts.
The Rev 2 boards have an additional chip which works around a bug in early AIM-65 boards. We know the problem was in rev 1 and rev 0 AIM boards, and it was definitely fixed on rev 4 boards, but I don’t know exactly which revision fixed the problem. Basically the RAM_R/W signal (pin Z on the Expansion connector) had the inverted Phase 2 clock NAND’ed with R/W. The SYM and AIM were both supposed to follow the KIM standard, but Rockwell got this one signal wrong.
Rev 2 boards have replaced the jumpers with a pair of 8 position DIP switches; those are easier to set and there are no jumpers to get lost ??
When running the ROM BASIC, this is what gets displayed:

MEMORY SIZE?
WIDTH?

 32255 BYTES FREE

BASIC V1.1
COPYRIGHT 1978 SYNERTEK SYSTEMS CORP.

Nice.

I’ve configured RAM from 1000-7FFF, B000-BFFF, and F000-FF7F. That gives a lot of room to squeeze in useful add-ons to the monitor.

SYM AIM 60K RAM docx
SYM AIM 60K RAM pdf


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Corsham github

Bob Applegate used github repositories to archive and supplement some of his projects.

While this github archive is still up (August 2024), it may go away too.

So here dumps of the repositories. Some of the contents may also show up in the Corsham projects archive pages.

6502 Tiny BASIC
# 6502 Tiny BASIC
This is Bob Applegate’s (bob@corshamtech.com) spin of a Tiny BASIC interpreter for the 6502. It uses an IL approach, like proposed by Dr Dobb’s Journal in the first few issues. This is not fancy, it’s not bug free, and it’s not amazing by any means, but it was fun to write and decent enough to do fun stuff and run demos.

CTMon65
CTMon65 – 6502 monitor

Eagle Libraries
These are libraries used in Corsham Technologies LLC prodcuts (www.corshamtech.com).
# SS-50.lbr
This is for constructing SS-50 and SS-30 compatible boards. It includes both male and female Molex connectors. For constructing plug-in boards using a female connector my suggestion is to place the center of the library part 0.15″ above the bottom of the board.
# S-100.lbr
This is for constructing S-100 boards and is, for now, more of an experimental library rather than something that has any sort of polish about it. Feel free to use but don’t be too disappointed when it does not meet your expectations.

Kicad SS50
# KiCad SS-50 Library from Corsham Technologies, LLC
This is a free to use library that was developed during our creation of
various SS-30/SS-50 boards.

KIM Monitor
# KIM-Monitor
KIM monitor as modified for the Corsham Tech KIM Clone board.

Music Board master
# SS-30 Music Board
This is a rough recreation of the Newtech Computer Systems model 68 music board. No atttempt
was made to make it look exactly like the original, but it is 100% compatible and uses the
same components as the original.

SD Drive
SD Drive Arduino firmware

SD Shield Tester
The SD Shield Tester is a program to test the Corsham Technologies SD Card System shield. This is primarily a manufacturing tool but can be used for general testing. It’s not very useful, but if you suspect an SD Card shield is malfunctioning, this is a way to test it.

xDbg
# xDbg
xDbg is a 65C02 debugger meant to compliment the Corsham Technologies xKIM monitor

xKiM
# xKIM
xKIM is an extended monitor for KIM computer systems. Commonly used in Corsham Technologies KIM-1 add-on boards.
It is a 6502 based monitor which has basic tools as well as some additional commands for working
with the Corsham Tech SD Card system.

xSBUG
xSBUG
This is the Corsham Technologies version of the SWTBUG SBUG monitor for the 6809. It is close to the original but has support for the Corsham Tech SD Card System (emulates disk drives).

xSWTBUG
xSWTBUG
This is a modified version of the SWTPC monitor SWTBUG for use on their 6800 based SS-50 systems. It has additions for the Corsham Tech SD card subsystem and other minor improvements.

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Corsham projects

As you can read below in the screenshot of the last post on Corsham’s website below, Bob has left us. I will miss him, a dear friend with whom I exchanged many emails about the KIM-1.

To honor his legacy I have collected on these pages everything available, from his former website, Github repositories and information I have received from Bob, enhanced with photos of Corsham products I have bought over the years.

I have decided not to replicate his website. Instead the structure is about all of his projects, current and past, with on each page all information available to me about the product, enhanced with available material from outside.

Note that I do not have more information. I do not have the PCB designs. I do not sell any Corsham product. All I have is here is what Bob once published.

Links
The Corsham Technology website used to live at https://www.corshamtech.com
Bob’s private website is still up (August 2024) at https://k2ut.org/
The Github repositories are also still up at https://github.com/CorshamTech
The forum at groups.io is here: https://groups.io/g/CorshamTech/

Pages you find here:


The last message on the Corshamtech website with the sad news about Bob.

Bob Applegate at his desk

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Bus extender

Bus extender

A handy bus extender from Retrospy. I glued labels from the KIM-1 manual on it, the PCB labels are wrong. PCB edges pads could be a little longer.



KIM-1 Application and Expansion labels for Bus extender

RetroSpy Technologies produces a range of retro (Vintage) hardware products that are of interest for the KIM-1/SYM-1/AIM 65 owner. Also the PAL-1 user may benefit from the products!
Retrospy is inspired by the Corsham Technologies products and since Bob Applegate is no more among us, produces similar/inspired products.

I bought several products from RetroSpy.
KIM-1 RAM/ROM Board
MOS 6530 Replacement for the KIM-1 SBC
PAL-1 Motherboard Expansion Kit
Bus extender

Other interesting KIM-1/AIM 65/SYM- related boards on the Retrospy shop:
AIM 65 I/O board
SYM-1 I/O board
SYM-1 SymDos I/O board
SYM-1/AIM-65 RAM/ROM board
KIM-1 I/O board
2532 to 2764 EPROM adapter
SD Card Storage System (like the Corsham one)

I should have bought he KIM I/O card also, for the 1541 connector, next time!