ISA DiskOnChip and Clock Board
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- Опубліковано 12 вер 2024
- In this video, I create an 8-bit ISA board for trying out some DiskOnChip ICs that I bought on eBay. There was some extra space on the pcboard, so I also added an optional real-time clock IC. I describe how to replace the boot loader on the DiskOnChip, look around the existing data (nothing exciting there), and then reformat it. For more retrocomputing projects, see www.smbaker.com/
Cool project. I created a cut-down Linux distro around 1999-2000 that fit on an 8mb DiskOnChip devices. M-Systems made an 8-bit ISA card and software to flash them, which this reminds me of. It was a hassle to use, since you had to power off the machine, pull the card, install the DiskOnChip, power up, program, power off again etc. Once I had an image that passed QA, that got sent to China and programmed onto the shipping machines.
Very cool. I was thinking these would be perfect for a small embedded Linux device.
thanks so much for this video, i managed to get my 192mb working and updated firmware on the same 8mb chip you have. Now i can install win95 on the 192mb and have a true single board pc in my macintosh classic project without sd card adapters etc
I attempted replicating the DiskOnChip portion on dotboard to adapt this to a Commodore PC-1 ... turned out I can only get it semi-stable when using a 74HCT688 (in a static setup like on the Lotech XTCF - going with the DIP switches + pulldowns already makes it glitch out) and buffering the data lines with a 74LS245 (without pullups seems to be fine). I actually tried a ton of different approaches as it got obvious early on that the timing appears to be extremely sensitive ... 74LS688 + various pulldowns on critical signals, 74LS138 + 74LS139 or 74F138 for decoding or buffering the adress bus + control lines via 573 latches.
Also: Be careful about rewriting the bootloader ... turns out it's bad on all my DOCs after rewriting ~15 times (they can still be used fine by manually loading the drivers).
21:00 maybe laser printed transparency behind the clear front to help label those switches! maybe try different colours and backgrounds even! and maybe even fancy mood lighting behind, ****shrugs****
Could have been something McDonalds related. PCPOS (their old register software) was DOS based and there was a device/server called the CCU at one point involved. I'd have to go through a lot of my own old notes to see what the CCU executables were called.
These filenames look pretty similar to the ones I found in my "Hidden 386". It was a wireless networking access point (pre-wifi 2.4ghz protocol) that was a 386 machine without video, and an internal floppy drive to provide a boot medium. Maybe at some point they upgraded to a disk-on-chip?
Very interesting. It did feel to me like potentially some kind of LAN equipment, though I couldn't find any manufacturer identifiers anywhere. There was one very large INI file that appeared to contain what looked like IP addresses or portions of IP addresses, but each prefix assigned to a high-ASCII string. About 7000 of them. Given the mix of normal ASCII together with high-ASCII characters that make no sense to me, I wonder if the INI file is written in a language that I don't have the proper environment to display.
Nice project, though a little light on the clock side of things. Can you delineate the dip switch settings and mention what clock reading software you are using?
Fascinating. I picked up a strange pc having a backplane and sbc x86 and have been wondering about the plug over the cmos microcontroller (that is where the "Disk on Chip" device goes, right? New territory for me.). Mine had Win95NT on it and, on boot, it tried to logon to a couple overseas servers too.
Scott, Have you stumbled upon documentation of how writing should be done? Which registers to set etc… I'm thinking about a scenario where this chip would be used inside a non-x86 retro computer, so the built in BIOS extension wouldn't be used.
Which program are you using for RTC?. I've tried like +10..and no one works :(.
Thanks...still using your BOARD for booting in my XT (using disk on chip + xt-ide)
Ohh yeah, I forgot those exist!
Neat stuff
My guess is dos 6.22. That time stamp!
Thank you. Can i ask you if the rt809h can read this Chip?
Any chance of using as ram extention as well? like up to 1 meg for 8086/8?
where can i find the dipswitch setting for this card
Thanks for the project. Max disk-on-chip size that the card can take?
Also, is there any new BIOS firmware needed, e.g., upgrading to my computer (an old AT computer -- part of my collection)?
I read your page at www.smbaker.com/8-bit-isa-diskonchip-rtc-board, but it does not mention of any updated BIOS firmware needed.
It does sound like I would need the DUPDATE.exe utility to flash the boot image onto the chip. Where would one get the DUPDATE.exe utility?
Thank you!
I'm having a bad day making this thing to work. I´ve achieved to write to the DOC in address E000 in a machine where it won't boot from (Pentium MMX, too new maybe?). I have a 486 where it loads the DOC ROM, but only when no IDE or floppy controllers are installed, so I can't install anything. I have the PCI card where the DOC originally came from, and I've tried to install it in a newer machine (Athlon XP, it has an ISA port but it won't boot if the DOC with the ISA adapter is installed) and by disabling every IDE controller it gets to boot from the ROM but restart sor halts before getting to the floppy. If you have any clue of what's happening i'd appreciate the help.
OK it was the IDE controller. I got one working in the 486 and it can boot from floppy after loading the ROM, but for some reason there are errors reading the floppy when the DOC is in the system. If the card is in the PC without the DOC chip it reads fine, but with the chip in the socket it just doesn't work. At this point I'm suspecting on the DOC itself, what a shame.
Hi,
What is the resistor network ohm value, that is, the yellow component on the board connected to the dip switches for the disk IC?
The schematics does not say.
Thanks
They're pulldown resistors, probably anything along the lines of 4.7k to 10k will work.
@@1337Shockwav3 Yeah, in theory you can save a tiny bit of power by going with larger values but it becomes susceptible to electrical noise. I try not to go above 10K for stuff like that, though if you were really worried about power, you could use larger values if you add a capacitor as well.
CCU = Camera Control Unit?
Isn't there a /q flag to do a quick format? I suppose it was a good idea to check this for any bad sectors due to its age, but that's usually a waste of time
He uses DOS 3.31, so no (you need 5.0 for that).
It doesn't always work either. Not sure about the disk on chip but, Dos 6.22, Windows 95, and Windows 98se bootdisks all refused to quickformat my ide to sd card drive in my pentium 3 laptop.
Okay. I think I have found them - Disk On Chip utilities version 4.20 - www.digital-circuitry.com/FILES/M-SYSTEMS/DOC/DOC_SOFT_UTILS/DOC_V4.20.zip - there is a newer version 5.14 but it does not appear to support 8086/8088 cpus.
its posible downgrade the firware?
18:48 should backup. sadly your formated it
You make this too easy.