On Sat, 27 Jun 2020, W2HX via cctech wrote:
> Peter and Maciej. Thank you very much for the input. I don't believe
> this BIOS supports anything other than CHS. At least I don't see a way
> to toggle between CHS and LBA. Is this what I should be looking for? An
> option to enable LBA mode?
IIRC some old PC BIOSes indeed had an option to switch between CHS and
LBA, it's been a while. It might have been on a per-drive basis, at least
with some implementations; as usually, for bug compatibility or whatever.
This was all hairy stuff, now that you have reminded me.
Using Linux did help a lot back then, the system was especially ambitious
in its early days (it has fallen a bit into routine IMO over the years;
it's no longer hobbyists trying to make their best and squeeze out as much
as possible from the hardware), so all that was necessary was to put all
the boot stuff onto a partition within the first 528MB, even with fake CHS
parameters in the BIOS setup, and forget about all the PC BIOS limitations
as the kernel handled all automagically, including geometry discovery and
switching between CHS and LBA as necessary (IIRC there was an override too
for the user to pass at kernel invocation in case the firmware of a given
drive had a bug with one of the modes or whatever).
> I am not opposed to going to CF, but I have no other computers that have
> a CF port, thus I have no way to move files onto this 486 computer.
CF to PATA adapters are readily available and can be used to wire CF
media to any machine talking PATA. I have one of those adapters that
actually supports both a master and a slave CF device, so you can plug two
CF devices at a time, just as with original ATA devices on a flat ribbon
cable (from StarTech; it may not be available new anymore and I have it at
a remote location, but I can check the P/N when I'm back at it or perhaps
track down the original invoice in my e-mail archives if that would really
help you).
Of course you can bridge such an adapter to SATA or USB or whatever, just
as with a genuine ATA device, so you should be able to wire it to a modern
machine pretty easily. But actual PATA adapters for PCIe used to be made
too as I have a couple myself that I bought not so long ago so as not to
be stuck with vintage hardware for data copying involving a PATA device,
so tracking down one being sold shouldn't be a big deal yet.
You might be able to track down an actual hard drive in the CF form
factor too (branded Microdrive by IBM IIRC, a 1.8" device), though the
choice was rather limited. I have one of those from Seagate at 2.5GB,
extracted from a TomTom sat nav that I upgraded to solid-state CF of a
larger size several years ago. I used that dual CF adapter I mentioned
above to copy data between the two storage devices. Those true hard
drives ought to be pretty much compatible with anything, as they're
ordinary magnetic devices, just smaller:
/dev/hda:
CompactFlash ATA device
Model Number: ST625211CF
Serial Number: [...]
Firmware Revision: 3.04
Standards:
Likely used: 6
Configuration:
Logical max current
cylinders 4845 4845
heads 16 16
sectors/track 63 63
--
CHS current addressable sectors: 4883760
LBA user addressable sectors: 4883760
Logical/Physical Sector size: 512 bytes
device size with M = 1024*1024: 2384 MBytes
device size with M = 1000*1000: 2500 MBytes (2 GB)
cache/buffer size = 128 KBytes (type=DualPortCache)
Capabilities:
LBA, IORDY(cannot be disabled)
bytes avail on r/w long: 4
Standby timer values: spec'd by Vendor
R/W multiple sector transfer: Max = 16 Current = 16
Advanced power management level: disabled
Recommended acoustic management value: 128, current value: 128
DMA: mdma0 mdma1 *mdma2 udma0 udma1 *udma2 (?)
Cycle time: min=120ns recommended=120ns
PIO: pio0 pio1 pio2 pio3 pio4
Cycle time: no flow control=120ns IORDY flow control=120ns
Commands/features:
Enabled Supported:
* SMART feature set
* Power Management feature set
Write cache
* Look-ahead
* WRITE_BUFFER command
* READ_BUFFER command
* NOP cmd
* CFA feature set
Advanced Power Management feature set
* Mandatory FLUSH_CACHE
* CFA Power Level 1 (max 330mA)
HW reset results:
CBLID- below Vih
Device num = 0 determined by CSEL
Integrity word not set (found 0x0000, expected 0x1ca5)
> Is there anyway to add LBA mode to this machine? A new BIOS? A new ISA card?
You might be able to chase one of those sophisticated cards that I
mentioned, which obviously had their own expansion BIOS hooking up into
the PC BIOS. I don't know though how common they are these days on the
second-hand market. Some old hardware seems to be unobtainium, almost
never if at all surfacing, while other is ubiquitous. I don't know why.
I wouldn't bet on a PC BIOS upgrade for such a specialised machine. They
were supposed to be used in their supported vendor-provided configuration,
so what would be a functional firmware upgrade good for? A critical bug
fix is another matter, but that would not add such a major feature as LBA
support.
> Or am I better off considering a new motherboard altogether? Maybe more
> of a project than I was hoping for...
Another possibility would be a SCSI host adapter. They have always come
with their own expansion BIOS, so any limitations of the base machine's PC
BIOS are not relevant. I reckon there have been SD to SCSI adapters
available.
> I guess a possible solution might be IDE-CF card for the 486 and maybe a
> corresponding USB-CF for my daily PC for file transfer?
As I noted above I think an IDE-CF adapter is probably the easiest option
and you can use it both with your intended machine and with any other as
well. No need for a separate USB-CF piece to transfer data unless you
want that too, that is.
HTH,
Maciej
