My 8bits4ever SX-1!

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Van larsthe18th

Master (158)

afbeelding van larsthe18th

12-05-2019, 20:00

With my solution above i can't get 'EMUFILE.COM' to work sinds it uses the MSXDOS2 kernel ROM,
can i change/flash the NEXTOR ROM in to the SX-1 some how ?

It would be so nice if the USB port of the SX-1 could handle a 'USB Floppydrive' like the Rookie drive does.
Could this be possible ???

Van RetroTechie

Paragon (1551)

afbeelding van RetroTechie

12-05-2019, 23:06

larsthe18th wrote:

Yes, the powersupply has to be 9V - 2A with 'Center Negative' (2.1 mm) barrel .

In 2019? That is f**ing EVIL! Evil Otherwise looks like a great piece of kit (kudoz for that!), but center pin negative on a DC plug is so uncommon these days, that's like begging for trouble. IDIOT design decision, no excuse.

I assume they put in reverse polarity protection to go with that? Right..?? RIGHT??

Van Meits

Scribe (5398)

afbeelding van Meits

12-05-2019, 23:13

Didn't Dell do that as well with their centerpin adapters that looked like the ones HP used? That was evil indeed, but they forgave you if you used the wrong adapter. This one better have protection as well. It's not off the shelf stuff from the computer shop around the corner.

There was an ATX connector on their first version(s). If they reintroduced that, I'd have one.

Van zett

Hero (540)

afbeelding van zett

04-06-2019, 14:08

Hmmmm is it possible to better the vga output? i see that some dots are duble pixel size and others not. is it possible to adjust this?

Van KdL

Paragon (1197)

afbeelding van KdL

04-06-2019, 14:48

zett wrote:

Hmmmm is it possible to better the vga output? i see that some dots are duble pixel size and others not. is it possible to adjust this?

The VGA output is mainly designed for CRT monitors. If you use my firmware you can try a calibration with the VGARATIO extra command for MSX-DOS2 but it does not work on all LCD/LED displays.
I also suggest you update the firmware to get this functionality and to select DIP-SW2 / 3 = ON / OFF.

KdL Index!

Van KdL

Paragon (1197)

afbeelding van KdL

04-06-2019, 19:44

RetroTechie wrote:
larsthe18th wrote:

Yes, the powersupply has to be 9V - 2A with 'Center Negative' (2.1 mm) barrel .

In 2019? That is f**ing EVIL! Evil Otherwise looks like a great piece of kit (kudoz for that!), but center pin negative on a DC plug is so uncommon these days, that's like begging for trouble. IDIOT design decision, no excuse.

I assume they put in reverse polarity protection to go with that? Right..?? RIGHT??

I generally use a standard router power supply +12V 1A center positive.
Here is an old email explaining how it works. Wink

From: 8bits
Sent: Wednesday, May 23, 2018 8:04 PM
To: KdL

It can take any power supply between 7 and 28v (I recommend 12v so the converter does not stress so much). There is also a polarity rectifier circuit so you dont have to worry about the PSU polarity.

The button nearest to the DC barrel connector is ON/OFF. For the button to act, you need to let it rest for a couple of seconds after each push.

8bits4ever Team

Van RetroTechie

Paragon (1551)

afbeelding van RetroTechie

05-06-2019, 13:49

KdL wrote:

It can take any power supply between 7 and 28v (I recommend 12v so the converter does not stress so much). There is also a polarity rectifier circuit so you dont have to worry about the PSU polarity.

Ah okay, no worries then! Smile In this case specs should be updated to reflect that, though.

Out of curiosity I searched, found a detailed view of the board in this thread, and had a look. I noticed a couple of things about the power circuit:

a) For polarity protection, personally I'd put in a single 1 or 2A rated Schottky diode rather than bridge rectifier. Simpler, lower losses, lower voltage drop of ~0.3V (versus 1.5~2.0V for rectifier bridge with 1N4007 or similar). And - of the DC jack can connect directly to circuit GND which which can be useful sometimes. Stupid user who puts in wrong polarity then simply has no power, no harm done.

b) All 16V rated caps there, meaning: input is only rated for 16V max? (well a bit more due to diode drop). I'd put 25V or 35V rated cap on the input. DC/DC converter circuit has no problem with higher input voltage, so higher rated cap = wider choice what people can use as power supply. Note that this also applies to the rating of ceramic cap(s) on the input.

c) Most interesting: looks like a 680 uH inductor there? That's a really high value for use with an LM2596. Side effect would probably be a low voltage ripple on output, which is nice. But it would also limit available output current. Have they tested (as in: measured) output current this circuit (as seen in photo) can supply? I'd rather expect an inductor in 33..47 uH range there. 68 uH is already a high-ish value. Let alone 10x that.

Van Argon

Paragon (1074)

afbeelding van Argon

05-06-2019, 17:33

The guys from 8bits4ever told me both polarities should work with the SX-1.
The PSU can range from 9 - 12V and should have at least 2A.

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