MSC file for JTAG update with Xilinx IMPACT tool: f18a_250k_v18-mcs
In-System Update for TI-99/4A Computer: F18AUpdate_v18
A small update to fix a sprite collision bug where sprite collisions were being incorrectly detected outside of the active display, and added hybrid VDP register write restriction to mask VDP register writes […]
For a long time I hesitated engaging the idea of writing an SDRAM controller. I think my reluctance was due to the stigma that SDRAM controllers are extremely hard and complicated, and I always wanted something quick and simple. Once I finally committed to designing one, and after looking at two other more simplistic […]
Thanks to the help of several fellow 99/4A enthusiasts (Rasmus and Tursi), I’m happy to announce an in-system software update for the F18A firmware. Currently the update program only runs on a 99/4A system and requires a bulk-storage device large enough to contain the update program, bit stream, and data file on the same “disk” […]
Anyone interested in using the F18A in their own computer or microcontroller system, please start with the TMS9918A datasheet since the electrical interface, host CPU interface, and timing specifications of the F18A are the same as the TMS9918A. I’m only going to outline the F18A differences here.
Since the F18A runs at a higher internal […]
0.0 F18A Register Use Spreadsheet
The register use spreadsheet is essential to programming the F18A and shows how all the extra VDP registers are used and what features they provide.
Download the F18A_Register_Use Spreadsheet
Programming the F18A is very similar to the original 9918A VDP. Because the F18A is a pin-compatible replacement for […]
Mounting the F18A VGA connector to your system case is *highly* recommended! The F18A is not designed to withstand any pulling on the VGA cable and requires good strain relief. One good “tug” can easily rip the F18A out of the socket and bend or break the PCB pins on the bottom of the board.
Test of the Bitmap Layer
Since the F18A is now shipping (finally!), and the feature list is stable (heh, yeah right…) I need to get my website updated, and eventually write some documentation so people can use the enhance features. For now I will try to make a comprehensive list of the features with […]
Update: March 19, 2012
I learned over the weekend that ceramic SMD capacitors cannot be reliably soldered using a soldering iron. It seems the ceramic material expands at a different rate than the circuit board and causes microscopic cracks in the crystalline structure of the ceramic. Apparently this will cause the parts to fail over […]
I recently restored a Toobin’ arcade coin-operated (coinop) video game. Operators have a habit of doing some of the most awful things to games, so I had to undo some damage and stupid modifications, like changing the marquee lighting BACK to florescent from incandescent (which seems to be a favorite modification of operators for some […]
When I first started the F18A project I figured getting a minimal FPGA board to run it on would be easy. After all, I bought my fully loaded devboard for about $150, and the only thing I needed was the FPGA and a few connectors.
Well, I’m here to tell you it did […]