Sunday, July 28


Daily News Stuff 28 July 2019

One Man's Treasure Is Another Man's Treasure Edition

Tech News

Retrocomputing Journal

A couple of weeks ago my video of the day was an exploration of an enormous warehouse stacked twenty feet high in classic 8 bit and 16 bit computer hardware, ranging from old broken stuff that had been exposed to the weather for years and was basically unrepairable, to complete original systems still factory-sealed.

A few different retrocomputing hobbyists took the time to sort through the place (the owner is getting old and apparently not in the best of health) and more importantly, to take video of everything.  And an eagle-eyed viewer of one of those videos said:


And indeed it was.

Here's Mindset serial no. 854, complete and in perfect working order (the only thing that needed replacing was the fan), with original keyboard, mouse, joystick, expansion cartridges, software, and all documentation including programming guide and service manual.  There's even a dump of the custom BIOSes available.  (Several of them since it has two ROMs for the CPU and two embedded microcontrollers.)

Mindset 854 is a fully-expanded unit with 256k RAM and dual floppy drives.  And one - count them - one game.

Mindset was not a financial success, but the engineering here was better than anything that came to market for the next...  Ever.  Look at those expansion slots.  You pop the slot cover off, push the expansion cartridge in, and off you go.  None of the bullshit you have to go through with "modern" computers.  Just plug it in and go.

Anyway, they've gone back and scoured the warehouse and discovered more Mindset stuff, presumably in various states of completeness and repair.

And there is now one video about the Mindset on YouTube.  It's search result #5 for me.

Meanwhile, I've started on a BOM for the A750 as a sanity check.  Not including the case, PCB creation and assembly, or power circuitry (which might be very simple - the H750 only uses 500mW at full load), it comes to A$44.56 in qty 1 so far.  (Plus up to $25 in optional extras.*)

That includes:
  • STM32H750 microcontroller

    400MHz Arm Cortex M7 with 1060k RAM.  Might actually be 480MHz by the time I get anything working, because they're updating the stock with a new version.

  • iCE40HX1K FPGA

    Video upscaling and retiming; I'm proceeding on the basis that it will be needed.

  • Intel 5M80Z CPLD

    System controller, console video, and 74LS avoidance mechanism.

  • USB2514 hub

    This will convert one USB port from the microcontroller to four downstream ports.  Another advantage is that it has built-in ESD protection so you're less likely to blow up the entire system just plugging in a keyboard.

  •  2 x Winbond 8M NOR flash

    One in QSPI mode for running code (read-only in normal operation), the other in SPI mode for read/write storage.

  • 2 x VGA output

    One full-colour graphics, the other just for a two-colour text console for programming and debugging.

  • 2 x TinkerPort

    DA-26 port combining 8-bit parallel, 4-wire serial, 5V and 3.3V power, fast and slow clock sources, and GPIO on whatever pins are left.  One external for hacking, one internal for expansion.

  • 1 x USB type B

    Upstream connection to a PC or power supply.  Might be a micro B instead.  Carries both data (for programming / debugging / file transfers) and power (for power).

  • 4 x USB type A

    Two of the common two-high stacks.  USB 1.0 only unless I add a an external PHY.  Hmm.  How much is an external USB 2.0 PHY anyway?  Oh, A$1.90 qty 1.  I'll add that to the list for consideration.  Though with only 1MB RAM and 16MB storage you can transfer the entire system contents in or out over USB 1.0 in less than 15 seconds.

  • 10 x indicator LEDs 

    Mostly because I can get 3mm LEDs in 10 different colours at about 2¢ each.  Box of 500 for $10.74.

  • 21 0.5% resistors for VGA DACs

    15-bit colour on the main port, 6-bit on the console so you can have something resembling an amber or green screen.

    Plus a bunch more 1% resistors for general pull up/pull down/current limiting/whatever.

* Oh, need an SD/MMC slot or two. Those are about A$2 each. And at least one 1/8" inch audio jack. That's about $1, and I even get to pick a colour. So that's a another five bucks.  All drop rapidly to about half that price even in small volumes.

The other possible addition is general-purpose serial ports.  Not sure how much that is needed with upstream and downstream USB and the two TinkerPorts.  But RS-232 drivers are dirt cheap (at least if you do a minimal null-modem connection), and RS-485 isn't too expensive.

Replacing the main VGA port with DVI-I is the single most expensive option; that's a $12.38 difference for the driver chip and the DVI-I connector itself, which is about three times the price of a DA-15.

Actually, the most expensive option is the custom keyboard.  Those are US$160 each with Cherry MX Brown keyswitches, so probably three times the price of the computer itself.

Disclaimer: 3mm white, warm white, pink, red, orange, yellow, yellow-green, green, blue, and purple LEDs are about 2¢ a piece, with flat or rounded cap.  IR transmitters and receivers around 5¢, and the H750 supports IRDA, so I'll look into that.  Can also get amber (if that's different to orange), cyan, and turquoise, and various two-colour and colour-cycling variants.  But not proper RGB, not in 3mm.

Posted by: Pixy Misa at 11:08 PM | Comments (8) | Add Comment | Trackbacks (Suck)
Post contains 1071 words, total size 9 kb.

1 Do you know anything I can use to clone my UEFI, 3TB Windows 7 boot drive, that will result in an actually BOOTABLE clone? Macrium fails at that. I mean, it clones, but their "Fix Boot Problems" function on the rescue disk fails.

I mean, what's the point in cloning your boot disk if you can't drop it in as a replacement if it fails?

Hell, I can't even figure out how I managed to INSTALL windows on that drive again, since the installers I have (7 and 7 SP1) refuse to work unless I format it to smaller than 2 TB.

Posted by: Mauser at Monday, July 29 2019 10:56 AM (Ix1l6)

2 Man, watching that video makes me want to get a the parts to overhaul my Pentium II Windows 98 machine, and get a 486 with MS-DOS 6.0, and a full Commodore 64 rig.
I am still bitter over having my 486 (With the 5.25" and 3.5" combo drive.) and the Commodore 128 getting tossed while I was not at home.

Posted by: cxt217 at Monday, July 29 2019 11:28 AM (LMsTt)

3 Mauser:  at a guess:  mount the drive in an existing Windows installation, and create a single 3TB GPT partition.  Then put it in another machine and install Windows to that.  According to this page, that looks like it might work.

Posted by: Rick C at Monday, July 29 2019 12:36 PM (Iwkd4)

4 Mauser - you can read the rest of the drive, just not boot?  That's something, at least.

Windows 7 should be fine with >2TB as long as you have a UEFI BIOS (which you evidently do) and the drive is partitioned with GPT - which it should be since you just cloned it.

Here's the install instructions.

"From inside Windows Setup, press Shift+F10 to open a command prompt window."

About to break my PINF rule here...

Posted by: Pixy Misa at Monday, July 29 2019 01:15 PM (PiXy!)

5 Mauser: also, maybe this will work for you?  I think I originally misunderstood what you were asking.

Posted by: Rick C at Monday, July 29 2019 01:30 PM (Iwkd4)

6 Some of that rings a bell. At one point I tried to do a new install on the clone drive, (I used it as a scratch monkey for what I thought was a bad download, it was fine). But apparently the Windows installer wouldn't start in UEFI mode. I may have forgotten the trick (Also, I seem to have issues with my F10 key). The repair option on the installer also refused to work when the drive was formatted in GPT.

Still don't understand what's missing and why a pure forensic clone (at ~8 hours to run!) didn't do it.

Nice there's an MBRGPT tool, but Boo it only works in Win 10.


Maybe I should start a thread on my own blog so I'll have it as an easier reference.

Posted by: Mauser at Tuesday, July 30 2019 02:52 PM (Ix1l6)

7 PINF is something Brickmuppet said when I linked deadpan to a news item that was even more absurd than usual.  It stands for "Pixy is never facetious".

Posted by: Pixy Misa at Tuesday, July 30 2019 03:21 PM (PiXy!)

8 @Mauser I believe a straight clone leaves an issue in the master boot record that causes issues for Windows as the new disk has a different ID.   It's sounds your clone software didn't fix this.  Try: And:
(note, the links I grabbed are from some random sites based off a quick search, not sites I am particularly familiar with)

Posted by: StargazerA5 at Wednesday, July 31 2019 03:18 AM (jl9eJ)

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Apple pies are delicious. But never mind apple pies. What colour is a green orange?

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