12/14/2018 at 16:40 •
Too much empty space on our new V9958 video board. So, why not add more memory? Adding another 64k maxes out the available memory for the V9958 to a whopping 192k. These additional 64k are not usable by any of the video modes directly, but are treated by the chip as so called "extended memory". Using the command engine, data can be swapped from regular video memory to extended memory or vice versa.
We decided to not use the RCA Jacks for RGB output anymore, because there was not enough space on the board edge for an extra jack for sound. Instead, we decided to go with a DIN jack. We use the same jack the NeoGeo uses for RGB, which also has a pin for audio. So one single cable to connect an RGB-Monitor. Also, there are ready made cables available. Nice.
Also, having still space to spare, we decided to add the OPL2 sound chip to the video board, too, making it a "multimedia board". The V9958 also has a pin "CPUCLK", which provides the 3,58MHz clock needed by the OPL2 chip. Sound support only existed on stripboard or even breadboard, so it really was about time.
The analog stage of the sound section by the way was closely modeled after the one in the Commodore SFX expander for the C64.
Now, only 3 boards are needed to have a full featured Steckschwein including sound.
09/04/2018 at 13:09 •
Steve Wozniaks famous 256 byte memory monitor has been ported to the Steckschwein. Check it out.
03/20/2018 at 12:55 •
Like the 9929 board, the all new, all more powerful video board based on the mighty Yamaha V9958 chip has two parts – the video chip part with the 128k video memory (64k x 4 DRAM this time) and the signal part, using the Sony CXA2075M chip not only as RGB output stage, but also to generate composite video and s-video. This should increase the number of Steckschwein-compatible monitors a big deal.
The V9958 is the successor of the V9938, which in turn is the successor to our TMS9929/9918, which has served our project for quite some time. But it is hard to ignore what the V9958 has to offer (80 column text mode to begin with), so we decided to use it as the first major upgrade to the Steckschwein Hardware specs in a couple of years.