TMS9918A Static VRAM

[TcGmer]

I've been working on hooking up a tms9918 and a ay-3-8910 to a 6502 machine, which I based the design on ben eater's 6502 machine, and these videos you made really made the difference on the progress I'm making, for the glue logic since I don't have a 74x138 I designed some logic using nand gates and used the 6000 address space for the 6522 and the 7000 address space to the tms9918 (of course I had to mess a bit with the 6522 glue logic) and it all ended up working perfectly! If you read all this I just want to thank you for your work on making these videos and your care in explaing the viewer what's going on, greetings from Portugal!

[matthewwallace]

To anyone building this circuit:

When I first connected the all of the HCT574s' AD0-7 wires as shown in the video, my monitor outputted random values. I then flipped two of the HCT574s' AD0-7 connections, and it worked beautifully. I flipped the wires going out of the TMS9918A and into the left 574, and the wires coming into the right 574, relative to then ones shown in this video. It then worked perfectly!

[nowt]

Nice video. This project is pretty similar to one that I was working on back in 2019. I did actually use dram for the vdp chip but I used 4164s instead of 4116s. These are a bit easier to use as they only need 5v and I had some left over from repairing a ZX Spectrum.

I need to go back to that project, I had it working but it was getting a bit too flaky on the breadboards and I was spending more time trying to find bad connections than actually doing the computer.

I had an ay-3-8910 that was controlled through a 6522. The 6522 was also doing the baud rate generation for a 6850 uart. The computer was running Lee Davisons Ehbasic. The serial io and putting text on screen was done with interrupts with basic using a buffer for the chars. Watching these videos is giving me some motivation to get back to the project. I had quite big plans for it with a section of ram being paged and even an ide interface and implementation of a basic fat filesystem.

[ShaunJV]

I recently came across your channel and I'm really enjoying these videos! I hope you can produce more soon! It would be great to see you continue with this project

[matthewwallace]

This channel is incredibly underrated. You've been a huge help for my senior project!

[microhobbyist]

Ahhh! That's how it actually works. Thanks for clarifying things up.
I purchased some TMS9918A chips, I'll implement my video section soon on my 65C02 SBC.

[deepfried-pillow]

Thank you for making this video series - it's been a tremendous help with hooking up my own TMS9918 to a 6502 based computer I've been working on, and these videos have saved me a lot of trouble.
Thanks again.

[mbeware]

Interesting project. I would have love to see the sprite demo!

[MarianoLu]

How is the project going? I'm in the same boat so waiting for the next video!!

[theowinters]

A few months back I wrote an emulator for the version of the TMS9918A used in the Master System, so it's really interesting seeing this from the other side.

[goofyAAAAAAAAHHHHHHHHH]

AUUUG Through days of finding why my screen had blue garbled text I realized that as krallja said in the previous tutorial that the clock needed to be delayed a bit and at the time it worked without the delay (pin 3 of '138 connected straight to clk instead of connecting straght to pin 20 of 6502 ram for delayed clock) The circuit is now working wonderfully when inverting the clock line 4 times. Now i can start coding! thanks!!

[tylerlatham]

I've been anxiously awaiting this video. I'm so excited to see sprite mode as well. I have picked up some of these chips and plan on implementing this after I get my SN76489 sorted.

Also do you remember where you picked up those pliers with the red handles? They look great.

[inventr]

This is great! Any plans to make it work with a keyboard so you can type stuff onto the screen? I finished my BE6502 a while back and that's been my next goal.

[colonelbarker]

Thanks for this. Really interesting video!

[BalugaWhale]

Can you give us the link the the DRAM to SRAM solution? Seeing that simplification and your implementation was my favorite part!

[narayanbandodker]

I have a dumb question, is it possible to connect a PC DIMM to it? I'm not saying the modern DDR RAMs, but the first SDRAMs. I think it is possible to connect to it's bus but voltage may be an issue

[isaactanner]

Hi !!
Can you provide a schematic link with this latch converter to replace VRAM kind used in this project ?? Is a super good insight to replace annoying -5v in all projects !!
Thanx so much !!

[noureddinebenakrim]

You are awesome, don't stop making videos like this, thanks

[Hardwarenerd]

Happy new year! I hope you are having a great time! First question I have is where to get that 10mhz crystal?.. I've been waiting for this video! Time to expand my system

[Wobblybob]

That was awesome! Of course you could have used 4bit Drams and saved yourself alot of wiring. :-) Cant wait for the next installment.