Since the 6532 is in fact a subset of the 6530 (no ROM, more RAM), it seems not too difficult to make a 6532 replacement this way.
The reDIP RIOT is an open source FPGA board which combines the following in a DIP-40 size package:
Lattice iCE40UP5K FPGA
1Mbit FLASH
5V tolerant I/O
The reDIP RIOT provides an open source hardware platform for 6530 RRIOT / MOS 6532 RIOT replacements.
4 february 2025 2025 I have built the PAl-2 kit, now designing and building a I/O card.
This information is based upon the available documentation: User manual, Schematic, BOM.
The PAL-2 is for sale by Liu Ganning at Tindie
Just followed the interactive BOM, passive components first, ICs last.
Nothing special to note, compare yours with the photo on the PAL-2 Tindie site.
Orientation of IC sockets and IC’s, check twice!
Check your soldering joints, not too much sodler, but covered with the right color solder.
And the three slider switches,: the SST keyboard one has a higher slider that the other two!
Please be careful with the Dupont power cables, double check the polarity! If in error: magic smoke!
I do not like the Dupont wires for power, serial, TTY switch. Too easy to make a mistake in the power connection.
I am now designing and building a simple I/O card for the Application connector, experimenters print, point to point wires, male pin connector to PAL-2, on board female connector for USB to Serial, power switch, TTY/Keypad switch.
That may grow later to SD or 1541 or Corsham SD card interfaces.
Video of PAl-2 #4, by Nils, running!
What is a PAL-2?
The PAL-2 is a kit for an SBC in the now large family of KIM-1 clones. Ranging from the Micro-KIM to the PCB exact replica by Eduardo Casino, all share the KIM-1 ROMs, LED display and TTY interface and the 6532 RIOT instead of the 6530 RRIOT.
What makes the PAL-2 unique:
It is a real and complete KIM-1 clone.
Available as a DIY kit with high quality components.
The layout is close to the KIM-1.
The good looking keypad is very close to the KIM-1
Application and Expansion connector with all relevant KIM-1 signals.
Lots of RAM in many configurable options.
Both RRIOTS 6532 on board.
TTY interface on TTL level, USB to TTL adapter included in the kit, quality serial!
Power can come from the USB to TTL adapter or from external 5V supply (same as for the KIM-1)
The PAL-2 differs from a KIM-1
No Audio cassette interface for file I/O circuit, but see below for a solution
Application and Expansion connector as 22×2 pinheader instead of PCB edge connectors
The signals on the Application connector are not all identical: no audio, TTY instead of 20 mA loop, decoding lines added
Not the same size PCB
The PAL-2 differs from the PAL-1:
The many quality improvements and enhancements make the base PAL-2 kit more expensive then a base PAL-1 kit.
If you expand the PAL-1 to the level of a PAL-2 you need to spend money on a motherboard, a RAM 32K, a second RRIOT kit, an RS232 cable and gender changer and a 9V power supply.
Improved keypad, with labels and look of the KIM-1
No need for a Motherboard
No external RAM module required
No external RRIOT required
E000-FFFF can be used freely from ROM expansion
The vectors (Reset, NMI, IRQ) can be placed in external ROM.
RAM decoding
The PAL-2 has a very flexible RAM memory layout, as shown in the next parts of the schematics:
Internal ROM and external ROM
The PAL-2 has a 2K ROM with the KIM-1 monitor. Since there is no audio in and out circuitry, the ROM from 1800-1BFF could be used for other programs, like the KIM Clone by Corsham Technology (Which also did not have the audio circuitry). The 28C16 is easy to program.
One of the first expansions that is to be expected is an external 8K ROM. The decoding for this ROM, e.g. an 28C64 is already present on the connectors and in the decoding circuit.
The decoding signals are 8K7_SELECT (CE on 28C64) and 8K7_ROM (OE on 28C64). Just the 28C64 IC has to be connected to address and data lines.
DIP Switches
The PAL-2 has a full 64K address decoder onboard, while the KIM-1 has only a 5K onboard address decoder for expansion. These two DIP switches on the PAL-2 are designed both to expand the KIM-1’s RAM and to maintain compatibility with its basic configuration.
On the PAL-2, the 4-bit DIP switch enables the onboard K1 to K4 RAM spaces, with each bit controlling 1K of memory. The K1 to K4 naming follows the definitions in the KIM-1 user manual, covering the address range from $0400 to $13FF. If all four DIP switches are set to ON, the entire 5K RAM space becomes available to the system.
The 8-bit DIP switch controls the “big segment decoder,” with each bit corresponding to an 8K memory block. These blocks range from 8K0 to 8K7, with 8K0 ($0000 to $1FFF) being the KIM-1’s default occupied address space. Since the PAL-2 is a KIM-1 replica, if you want to use it as a KIM-1 system, 8K0 must be set to OFF to allow the onboard KIM-1 logic to function. However, if you’re building a completely new system on the PAL-2, you can set 8K0 to ON to bypass the KIM-1’s onboard logic for the lowest 8K of memory.
The 8K1 block starts at $2000, controlling an 8K space beyond this address, and so on. If a bit is set to ON, the KIM-1 system will be able to access the corresponding address space, which will function as RAM. If a bit is set to OFF, the KIM-1 system will still work, but with reduced available address space. When performing expansion or add-on modifications on the PAL-2, you may need to disable certain address spaces to prevent the onboard logic from accessing the RAM chip.
The 8K7 block, representing the highest 8K memory segment, offers additional flexibility on the PAL-2. If 8K7 is set to ON, you can choose how to use this space—either as RAM or ROM—by adjusting the 8K7 SEL switch. For example, if you write a program (such as a tiny OS for the KIM-1) and burn it onto a ROM chip—similar to the well-known Jim’s ROM (but smaller)—you can connect the ROM to the PAL-2 (with some additional hardware, which is still under development). To boot from your ROM chip, use the VECTOR SEL switch to select ROM, allowing the system to retrieve the top three vectors from the ROM chip instead of the onboard KIM-1 ROM.
Application and Expansion connectors
KIM-1 Application connector
Differences on the Application connector with the KIM-1:
AUDIO IN -> 8k7_SELECT
AUDIO OUT LO -> 8K7-ROM
TTY in and out now at TTL level for USB to TTL converter
TTY PTR and KYBD, +1wV, AUDIO OUT LO not connected
This means, even if the edge to pin connector issue is solved, the standard KIM-1 I/O boards will not work for TTY and audio.
The expansion connector is identical to the KIM-1.
KIM-1 Expansion connector
Power supply
Power has to be applied in the standard KIM-1 manner to the application connector Pin 1 = GND, pin A = 5V. Note that reversing these pins will mean the dead of the PAL-2!
Expansion
As a first suggestion for a PAL-2 extension I see a board connected to Application and Extension connectors with:
Power switch
28C64 (or bigger, switchable in 8K chunks) EEPROM
Connector for the USB to TTL
External power connector, switchable between this and USB to TTL connector
TTY/LED keyboard switch
connector for the Application I/O ports PA0-PB7
Power switch
Optional:
Pin connector for PAL-1 Cassette Interface audio board
The KIM-1 has hardware and software in the 6530-003 ROM to save and dump files on audio tape.
Not used by most KIM clone users, so it is not present on the Corsham KIM Clone and the PAL-2.
But it is possible to have the audio in/out with one patch wire between pin 11 of U12D and the application connector!
KIM-1 Audio and TTY circuit
PAL-2 Audio and TTY circuit
On the KIM-1 circuit you can see the audio I/O is seen by the CPU at pin PB7 of the 6530-003. It is either an input or an output under control of the audio routines in the ROM.
The U26 (also present on the PAL-2 as U12d) is an open collector NAND feding PB7. On one input of U26 is PB5 from the 6530/32 (inverted by U16 (KIM-1_ or U10D (PAL-2), on the other is the output of the audio circuit generating TTL pulses from the audio sound input. This way PB7can be used both as input and output.
The PAL-2 and the KIM-1 has on the extension connector the signal PLL(_TEST), which is connected to U126/U12D. This is on the KIM-1 the output of the audio circuit.
So we have audio in (at TTL level) on the PAL-2 covered!
Audio out is available at PB7 at TTL level. With a patch wire between PB7 (or pin 11 of the U12D) to the application connector.
With the PAL-1 Cassette interface we can have the PAL-2 read and write KIM-1 audio cassette files this way. PLL_TEST to TAPE and a wire from PB7 to PB7 is all you need to connect to the Cassette Interface (and GND and +5V ofcourse).
Leaving R9 out of the Cassette Interface may be a good idea, there is already a pullup in the PAL-2 of 1K.
Physical Dimensions
The connector on the PAL-2 is a 2.54 mm pitch 2×22 female pin header connector.
The dimensions of the PAL-2 PCB are 168 mm x 218 mm.
Next two images show the connector, first shows the distance between the two connectors, while the second shows the distance from the PCB edge to the connector’s outer side.
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:
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.
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 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.
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.
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.
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.
CODOS (Channel Oriented Disk Operating System) is the name of the Disk Operating System made by MTU for KIM-1, SYM-1 and AIM-65.
The DOS needs the K-1013 floppy disk controller, 8 inch disk drive(s) and optional the K-1008 Visible Memory.
CODOS V2 was the version for the MT-130/140. Lots of software was available, see the MT-130 page for manuals.
Dave Plummer (of Dave’s Garage) has a KIM-1 system with various MTU cards, including the K-1013.
