F18A Firmware Update

Downloads:

MSC file for JTAG update with Xilinx IMPACT tool: f18a_250k_v18-mcs

In-System Update for TI-99/4A Computer: F18AUpdate_v18

Checksum History:

V1.8

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 […]

FPGA VHDL SDRAM Controller

Introduction

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 […]

Disconnect Between the Layers

I have been programming for a long time, and for the last few years I started working on the hardware side of things too. Something that has really come to my attention recently is how much disconnect there is between the “layers” of producer-to-user. I suppose this kind of disconnect might also exist in other […]

F18A Programming Introduction

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

1.0 Introduction

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

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.

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F18A Features

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 […]

TIdBiT – TI BASIC Translator

Download: TidBit source

V3.0 – Updated on September 13, 2016

TidBit was created to help write TI-99/4A BASIC and Extended BASIC programs. TidBit is a pre-processor that lets you write your code in a more natural way (no line numbers, use indentation and comments, use labels, etc.) and then generates a normal BASIC/XB program that […]

Bank Switch Mini 256K

Bank Switch Mini 256K

When I started selling the Classic 64K Bank-Switch Boards on the CHC store, I wanted to follow Jon’s lead and offer a cartridge shell. Currently the only place to get a 99/4A cartridge shell is to removed the circuit board from an existing TI produced cartridge, at least until someone […]

F18A – FPGA Based TMS9918A

The TI-99/4A Master Title Screen on a VGA LCD monitor

Development Journal Index: The FPGA Development Board September 7, 2010 FPGA Education, Books, and Community February 1, 2011 Learn VHDL or Verilog? February 5, 2011 Making Boards July 14, 2011 F18A PRE-ORDERS Open! February 9, 2012 F18A Features July 21, 2012 Mounting the F18A […]

Integer to ASCII Conversion in Assembly

I wrote this code to demonstrate how to convert a binary number into ASCII digits for display on the screen. This is a complete program that has been tested on a real TI-99/4A computer. The code assumes VDP graphics mode I (the default) and includes the VDP routines I wrote as replacements to the ones […]