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Creating the F18A – An FPGA-based TMS9918A VDP

2/16/2011 04:25 AM EST
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matthew180
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re: Creating the F18A – An FPGA-based TMS9918A VDP
matthew180   2/18/2012 3:56:58 PM
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Harry, My initial development started on a Xilinx devboard board (Spartan 3E board), and I don't see any problem with using the DE(0,1,2) boards. I did use a few Xilinx specific components like the DCMs, but I think you would have to do that for any FPGA. Also, the design is set up to work as a stand alone VDP and communicate via a real external bus in a host computer. For internal SoC stuff, some modifications would be required (the current design would not work well as a drop-in core to an SoC). The other possible issue is, the F18A uses a lot of the block RAM. 16K is quite a bit for the smaller FPGAs, and this might be an issue if the design you were trying to use the F18A in required a lot of the FPGA's block RAM. The F18A also relies on the dual-port nature of the block RAM, so changing it to use an external memory would require extensive redesign. Aside from all that, it would possible to use as a VDP in a larger project. :-)

Harry  H
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re: Creating the F18A – An FPGA-based TMS9918A VDP
Harry H   2/18/2012 9:20:09 AM
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Hi. Is it compatible with the SPARTAN or ALTERA DE1 boards? Many FPGA programmers/developers using such boards would find it useful to have a plugin VDP. Having a plugin/external VDP would free space on the FPGA chip for other logic. All the best...and WELL DONE

matthew180
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re: Creating the F18A – An FPGA-based TMS9918A VDP
matthew180   2/10/2012 3:43:56 AM
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Pre-orders are now available for anyone interested in being in on the first batch of boards. See my web store at codehackcreate.com Thanks everyone for the support! Matthew

Werzel
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re: Creating the F18A – An FPGA-based TMS9918A VDP
Werzel   1/29/2012 4:01:59 PM
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Great PROJECT !! Will there be two versions.. One for NTSC (American) and one chip for European (PAL) systems. Or will there be one Chip that is switchable from NTSC/PAL by software ?? All the best ..and keep soldiering on !

matthew180
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re: Creating the F18A – An FPGA-based TMS9918A VDP
matthew180   1/12/2012 9:12:27 PM
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The F18A is not in production yet, but soon (I hope.) They will be available from my website (codehackcreate.com), where I post updates (although not as often as I'd like.) I also have a thread dedicated to the F18A on the AtariAge forum in the 99/4A section. Currently the F18A supports the 9938 80-column mode, and I do have other enhancements, of which multi-color sprites are included, as well as horizontal and vertical scrolling, and a lot of other extras.

Lez Anderson
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re: Creating the F18A – An FPGA-based TMS9918A VDP
Lez Anderson   1/12/2012 7:37:10 PM
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Where can you buy the F18A chip from ?? and how much will it cost...?? Does it have an 80 column display or is one planned, Are there any multicolor sprites planned ?? Best Regards and well-done!

matthew180
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re: Creating the F18A – An FPGA-based TMS9918A VDP
matthew180   12/1/2011 7:21:01 PM
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Hey Adam, thanks for the reply! I'm still planning on doing a 9900 SoC (probably starting with the 99/4A) and having access to the information and hardware you have would be awesome! I knew the 990 minicomputer was based on the 9900 CPU, but I didn't know the 990/10 had a discrete logic CPU! Talk about a goldmine of information, wow! I'll get a hold of you via email.

Adam.Roman
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re: Creating the F18A – An FPGA-based TMS9918A VDP
Adam.Roman   12/1/2011 5:39:54 AM
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Hey Matthew, great article, thanks for sharing, blah, blah. I am also a long-time fan of Mike's inspiring FPGA Arcade site, the TI-99/4A, and the TMS9900 (especially its cool assembly language.) I have, for some time, been thinking of squeezing the 9900 and 9918A into a little 5mm square Actel chip, but time and other things have not yet permitted such a project. But to that end, I acquired a few years ago a very large amount of TI990 equipment, information, and disks. I have several complete systems, including many TI990/10 processor boards, which are basically the standard 7400 series logic chip implementation of the TMS9900 before it became a single chip. (I imagine this could be of use, especially the various PROMs.) I also have the much expanded 990/12 systems (check out That assembly language in docs on bitsavers.org!) as well as 990/10A boards and the later Business System 300A, both based on the interesting but somewhat disappointing TMS99000 chip. I realize some time has passed since your article, but if this is still of interest, feel free to contact me. (Once I refresh my memory a bit, I also have extensive knowledge on this processor that needs to be utilized. I spent many an hour studying those schematics a few years ago!) I am near Chicago and will gladly help if I can. Best regards, Adam Roman

matthew180
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re: Creating the F18A – An FPGA-based TMS9918A VDP
matthew180   4/6/2011 4:53:25 PM
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Thanks for the feedback, I'm glad people are enjoying the article. If you ever find your 99/4A and it is not working, chances are it may be the VRAM (a DRAM failure), and the F18A board would fix that problem. ;-) The project is actually moving along and I'm on my second round of prototype boards. If all goes well, production should begin by the summer. Sadly I'm behind on updating my journal, as usual.

Leowise2010
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re: Creating the F18A – An FPGA-based TMS9918A VDP
Leowise2010   4/6/2011 4:26:09 PM
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Matthew, excellent article! I also had a TI TI-99/4A as one of my first computers, I am not sure where I last saw it (it was no longer a working system, sad) I am also learning FPGA programming and I agree with you, it hard but rewarding. Great work, hope you finish your project and hope you post a follow up article about your adventure!

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