CS/A65 Gecko
(C) 1997 - 2007 André Fachat
In 1997 I started developing an extra CPU board for my
CS/A65 system, but now without
an MMU and with additional I/O on board. This resulted
in the Gecko board. Some of its features are:
- A fast serial RS232 interface, using the 16550 UART with
FIFO, known from the PC world.
- A serial IEC bus interface to the Commodore C64 and VC1541
- An interface to infrared LEDs to remote control devices like
CD player or TV sets
- A small keyboard interface
- Up to 30 kByte ROM and 32 kByte RAM, with up to 2 kByte fully decoded
I/O space
- Bus interface to standard CS/A peripheral interface cards
- When used as a slave board to a normal CS/A65 system, the ROM can be reprogrammed in-system (when using an IC like the 29C010).
Software support is available with my GeckOS operating system, as well as with the drivers
provided on this page.
An old description up to version 2.1 can be found in
the old page
.
2007-06-27
Added a new re-design of the Gecko board. See the
board description below.
2007-06-27
I have relicensed the board to use the same license
as the other boards (previously it was non-commercial
only)
The System is built from a 6502 with some RAM and ROM.
Additionally it contains a UART 16550A for an RS232 interface,
as well as a VIA 6522 for some other I/O:
- Infrared sender - to control stereo equipment, VCRs, TV sets etc
- 4 bit in/4 bit out - for example for a small keyboard
- Commodore IEC bus - master or slave, so it can be used as
controller or as device (drive)
The system also contains a CS/A65 bus adapter, so it can be
plugged into a CS/A65 bus. In this bus it can either take
the role of the master (using all the ICs) but only for the
bus' I/O area. But it can also take the role as an I/O/Memory
board itself. Here a number of ICs must be removed
and some jumpers set specifically.
Most of the drivers have been tested using the
board in the slave mode - using the PET setup of the
CS/A65 computer (The PET setup uses the IEEE488
interface to load the files).
This driver implements a normal PET ROM - but
using the Serial (RS232) interface as terminal.
I.e. it replaces the standard PET Basic4 editor
ROM with a new ROM that uses the RS232 interface
instead. This version uses the VIA T1 interrupt
to implement the system interrupt. The Backspace key
is used as STOP, and due to character code conversion
(or lack thereof) input must be in capital characters.
The archive contains the source code for the new
editor ROM, and two binaries. One "uarted" is the real
Gecko editor ROM, the other "lduarted" is a PET BASIC executable
that loads into the Fat40 setup of the CS/A65
computer and uses the BIOS card's RS232 interface.
The infrared device is controlled by VIA PB7.
This driver implements a small PET program
that allows to send infrared commands to a
TV set and a Sony stereo. Other commands
can be implemented as well.
This driver (PET program) reads the drive
status of a Commodore IEC disk drive.
This driver (PET program) uses the 4 bit in/4 bit out
port to handle a small keyboard. The keyboard
uses a 74LS145 4-to-10 open collector decoder
(similar to the PET keyboard) to select one of
ten keyboard columns, with 4 keyboard rows as
input bits.
Status: schematics tested
Notes
|
In addition to the 3.0C version this implements the
ability to reprogram the ROM in-system - in case it
is a 29C010 for example. Unfortunately this only
works when the board is used as a slave, and only
when the board I/O is mapped into the bus I/O
area and not into the memory area.
|
Files
Status: schematics tested
Notes
|
This board fixes the bugs in the 3.0A version.
|
Files
Status: tested with bugs
Notes
|
This board is the redesign of the original
Gecko board. It misses some important jumpers
to use the board as an I/O/Memory board slave in a
CS/A65 system. Also it misses the /IRQ diode for the
WDC VIA, and Pin2 of IC9A is wrong.
|
Files
Status: ok
Notes
|
This is the Gecko 2.1 version that adds
the ability to use the board as I/O or memory
board (slave) in a CS/A65 system.
|
Files
Status: ok
Notes
|
This is the original Gecko 2.0 version
|
Files
