VCFe 20.0 – over and out

VCFe 20.0 is over, all of a sudden, and we had lots of fun as always.

Many thanks to everyone stopping by at our table, especially to those who voted for us at the poll. We got the fo(u)rth place.

Special thanks to Michael Steil, Andre Fachat und Marco Baye for hanging and hacking with us.

Very special thanks to Andre Fachat for his inpromptu 6502 talk right before our turn. I think we did prepare a real feast for every 6502 afficionado.

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Vintage Computer Festival Europe

Das VCFe steht wieder vor der Tür. Am kommenden Wochenende, also vom 27.4. bis 28.4., findet das Vintage Computer Festival Europe in München statt.

Das diesjährige Motto ist “Pixelritter – Programmieren am Limit”.
Und auch auf dem Steckschwein werden wir Pixel zeigen, teilweise am Limit programmiert.

Veranstaltungsort ist das Kulturzentrum Trudering

Wasserburger Landstrasse 32
81825 München

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Make Munich 2019 – It’s been our pleasure

Make Munich 2019 was awesome. Thanks to everyone who helped making this great event possible.

Again, we are stunned by how much positive feedback we got from so many people. Thank you all!!

Also, like in 2016, our booth was partly turned by a lot of kids into the official Make Munich arcade. So we definitely need to write more games. And build more Steckschweins. Let the children play.

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Meet us at Make Munich, 2.3. – 3.3.2019

Check out our homebrew 65c02 8bit goodness including our brand new video/sound-hardware at the Make Munich fair. We’ll also have BASIC, Forth, a couple of games and candy.
Our booth is in Hall 1, Booth Nr. 49, in the “Electronic Innovators”-Area. The did get that right, didn’t they?




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Fixing the white screen problem on a Tekway DST1062B oscilloscope

The Tekway DST 1062B (also known unter the Hantek or Voltcraft brand) is an inexpensive 60MHz digital storage oscilloscope, which is very much hackable and has proven to be worth its weight in gold pressed latinum.

More recently, my scope became affected by the infamous white screen problem, which apparently is a problem quite common to this model and its 100MHz or 200MHz siblings.


The Tekway/Hantek white screen of death

The screen just goes white, but the scope otherwise responds to pressing buttons, etc. so it appears not to be completely dead.
Some research revealed bad connections inside the scope as a possible culprit:
But in my case, that did not do anything.
More research brought me to a couple of messages within the famous Tekway hacking thread on the EEVBlog-Forum:

Forum member “bbf” told me during a conversation, that he had replaced the 3.3V regulator, but did not remember exactly, which regulator he used.
With this information, I went to examine the power supply. The 3.3V rail is powered by a KA78R33 regulator, which is rated for a maximum current of 1A. I removed it in order to power the 3.3V rail directly from my bench supply.


That’s a lot of load for the stock 3.3V regulator

And there we have it. The KA78R33 is under a constant load of almost 1.3A. Also using the bench supply I could play around with the exact voltage and I found out, that the scope is very sensitive about the voltage being correct. A voltage drop down to 3.2V will make the screen go white again.
To make things worse, the KA78R33 is completely potted in plastic, which I don’t imagine to be the best idea in terms of heat dissipation.
So we obviously need a beefier 3.3V regulator. I decided to go for a LM1085 which is rated for 3A, so we have plenty of safety margin. Also, it is almost pin compatible with the KA78R33, if inserted “the other way around”. Also, the LM1085 does not have GND but Vout on it’s housing, so one needs to be careful to not have it touch anything it’s not supposed to.
So with the new regulator, the scope works like a charm again.

Originally, the scope was sold as fanless, which was a big selling point for me back then. Inside, there happens to be a place to mount an 50mm 12V fan, also the power supply has a 12V rail just to power a fan. To be on the safe side from now on, I installed a fan. I just replaced the 12V regulator with a 9V one in order to keep fan noise down.


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V9958+OPL2-Boards are there

The newly made boards made their way from China to Munich. Starting now, the multi board version of the Steckschwein is made up of 3 Boards: CPU/Memory, IO/UART and V9958-OPL2.

Posted in dram, kicad, layout, platinen, RGB, sound, V9958, vdp, video, video chip, ym3812

New V9958-Board with integrated OPL2

It’s time for another hardware upgrade. Since we really want to get our single board Steckschwein done, we are going for higher integration of our multiboard prototype. After integrating the UART to the IO-Board, we integrate the OPL2 sound part onto the V9958 video board, so the current Steckschwein multi board incarnations are reduced to three boards.
We did postpone our plan to upgrade sound to OPL3 because Daniel Illgen, which we met at VCFb, convinced us with some awesome OPL2 tunes that OPL2 is still cool. Also, we save the extra oscillator, since the OPL2 can be clocked using the CPUCLK-Pin from the V9958, which happens to provide 3.58MHz.

We did upgrade however the video ram. The first prototype had Bank 0 and Bank 1, maxing out vram at 128k. We decided to include the Extended memory bank, too, this time, giving the V9958 extra 64k, which can be accessed using the blitter command functions. Why not?


KiCad 3D rendering of the new board

Also, to make the connector side more compact, we decided to not use RCA jacks for RGB anymore, but an 8pin DIN jack, which also carries the audio signal. So hooking up a 1084 Monitor or TV will only require a single cable. We use the same DIN jack and pinout as the NeoGeo uses, so there are even ready made cables available.


Posted in kicad, layout, opl2, platinen, RGB, SCART, sound, V9958, video, video chip, video signal, ym3812