kair.us/ projects/ hardsid_isa/
Hardsid ISA clone
This is a reincarnation of the Hardsid
clone which I made almost 20 years ago. The back story on that
page is true, me and my colleague really had intention to make a PCI
version which would be software compatible with the Hardsid ISA. We
had working code for PCI interface implemented with Altera FPGA from
another project. It didn't really support all the PCI features, but
it realized a few I/O addresses for read and write operations. When
the official Hardsid PCI was released, we kind of lost the interest,
even though it would have been a fun project.
I didn't receive any emails about the Hardsid replica schematics and
layout files until the last two years. I have had a few requests if
I still have the Gerber files available. Sure enough, I still had
the Eagle design available. Instead of just providing the Gerbers, I
have made some slight changes to the layout as well. My original
design was nearly 100% clone of the original Hardsid ISA. But it was
difficult to source the ISA bracket for that. I used one from ISA
network card but it wasn't really a good fit. There are still ISA
brackets commercially available, and I chose to use the Keystone
9202, which is available from several distributors. It was
necessary to increase the board size a little, to accommodate the
9202 screw locations. I also swapped the EXT In and RCA out
connector locations in order to make room for the second screw hole.
These changes also make the board look different enough compared to
original Harsid ISA, hopefully preventing anyone selling this clone
as original. Below is Eagle3D / POV-Ray render of the 'new' clone
board.
Here are downloads for the design files, Gerber files and BOM. You
can order bare boards from PCBWay using
this link. And here is Mouser
shared project which contains all the components for the
project (except the SID!)
hardsid_isa.zip
Eagle .sch and .brd
hardsid_isa_gerbers.zip
Gerber files
hardsid_isa_circuit_diagram.pdf
Circuit diagram
hardsid_isa_assy_dwg.pdf
Assembly drawing
hardsid_isa_bom.xls
Bill of materials,
exported from the Mouser
project
9202_cutout.pdf
RCA connector hole drawing for the Keystone 9202 ISA
bracket
9202_cutout_step.zip
STEP file of Keystone 9202 bracket with hole
http://z80.guru/files/HardSID/ISA/
Hardsid ISA Windos drivers 9x, NT and 2000. The driver package
contains also manual which describes the jumper settings etc.
About component selection
Although the circuit diagram and assembly drawing indicate HC
logic family, I have selected HCT family parts for the Mouser
project BOM. This is because the ISA bus was originally specified
for TTL, not CMOS logic levels. I have used HC chips in my build,
and the board has been working flawlessly with several
motherboards. They have all been quite late models from late 90's
or early 2000, so maybe those have CMOS levels on the ISA bus
also. I think the original Hardsid ISA used LS family, but I can't
be sure because I didn't check the voltage levels. The markings on
the chips were sanded off and painted black. LS chip availability
seems to get worse nowadays, especially the 74LS574 is difficult
to get now. So my recommendation is HCT, but the HC and LS should
work as well. Just don't use a mix of HC and LS chips, it will
cause problems!
Note that I haven't ordered the complete Mouser project BOM
myself, so I can't be sure that all components are correct. If you
build this board with components from the Mouser shared project,
let me know about the results!
Photo
Finally, here's a group photo of the original clone and the new
clone. And there's also my Catweasel Mk3 PCI board as bonus. The
Catweasel is mainly intended as a versatile floppy interface, but
it includes a socket for SID also. The SID implementation on the
Catweasel is a little weird. It has a circuit to boost the
'digi-sound' on the MOS8580. But the filter capacitors are not
easily changeable, and their capacitance is chosen to fit the
MOS6581!
kair.us/ projects/ hardsid_isa/
page created 10.9.2020
last updated 26.3.2021 webmaster@kair.us
