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TonyDuell · 5th Jun 2020, 9:15 am

A number of the high-speed (45ns or less access time) 1-bit wide bipolar RAMs had separate Data In and Data Out pins. I've just been working on a device that uses a couple of the Hitachi HM6147, for example (4K*1 bit).

As an aside, I once built a colour (TTL RGB output) video display board using 3 standard ICs, and which needs 2 TTL signals from the processor (bidirectional, open collector driven). While it wouldn't be compatible with the SoC VDU board, it could certainly be hung off an MK14, you might even be able to use the flag and sense pins on the processor. The ICs were :

74LS04 (6MHz clock oscillator and a bit of buffering)
6264 (RAM, actually all you need is 1K*8, but the 6264 is common enough)
SAA5243 (yes, the teletext IC. You can read/write the video memory over the I2C bus you see...)

5th Jun 2020, 9:15 am	#46
TonyDuell Dekatron Join Date: Jun 2015 Location: Biggin Hill, London, UK. Posts: 5,225	Re: Mk14 vdu A number of the high-speed (45ns or less access time) 1-bit wide bipolar RAMs had separate Data In and Data Out pins. I've just been working on a device that uses a couple of the Hitachi HM6147, for example (4K1 bit). As an aside, I once built a colour (TTL RGB output) video display board using 3 standard ICs, and which needs 2 TTL signals from the processor (bidirectional, open collector driven). While it wouldn't be compatible with the SoC VDU board, it could certainly be hung off an MK14, you might even be able to use the flag and sense pins on the processor. The ICs were : 74LS04 (6MHz clock oscillator and a bit of buffering) 6264 (RAM, actually all you need is 1K8, but the 6264 is common enough) SAA5243 (yes, the teletext IC. You can read/write the video memory over the I2C bus you see...)