MOS Technology TED

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TED pinout

The 7360 Text Editing Device (TED) was an integrated circuit made by MOS Technology, Inc. It was a video chip that also contained sound generation hardware, DRAM refresh circuitry, interval timers, and keyboard input handling. It was designed for the Commodore Plus/4 and 16. Packaging consisted of a JEDEC-standard 48-pin DIP.

Video capabilities[edit]

The video capabilities provided by the TED were largely a subset of those in the VIC-II. The TED supported five video modes:[1]

  • Text mode of 40×25 characters with 8×8 pixels
  • Multicolor text (4×8 pixels per character, double pixel width in the x-direction)
  • Extended background color mode (8×8 pixels per character)
  • Multicolor Graphics 160×200 pixels
  • Hi-Res Graphics 320×200 pixels
  • 46μs of the 52μs long visible part of the scan lines is filled with pixels

These modes were largely unchanged from the corresponding VIC-II modes aside from different register and memory mappings (see the article on the VIC-II for information on graphics modes). However, the TED lacked the sprite capabilities of the VIC-II, and so game animation had to be done exclusivly with custom character sets like on the VIC-20. This restricted the graphics of C16/Plus 4 games versus the C64. On the VIC-II, sprites used 2/3 of the die area pushing the transistor count over that of the CPU. In contrast, the TED caches the color attributes on-chip, increasing the SRAM from 40 bytes to 75 bytes and does away with the external color RAM.

The TED did include two features that the VIC-II lacked: luminance control and blinking text. Fifteen of its 16 colors (black being the exception) could be assigned one of 8 luminance values, thus making the TED capable of displaying a far wider array of colors than the VIC-II. The full palette of 121 colors is shown below.[2]

luma # 0 1 2 3 4 5 6 7
Y 0.125 0.25 0.375 0.5 0.625 0.75 0.875 1
hue # Pb (rel.) Pr (rel.) . . . . . . . .
0 — black 0 0 0,0 0,1 0,2 0,3 0,4 0,5 0,6 0,7
1 — white 0 0 1,0 1,1 1,2 1,3 1,4 1,5 1,6 1,7
2 — red −0.3826834 0.9238795 2,0 2,1 2,2 2,3 2,4 2,5 2,6 2,7
3 — cyan 0.3826834 −0.9238795 3,0 3,1 3,2 3,3 3,4 3,5 3,6 3,7
4 — purple 0.7071068 0.7071068 4,0 4,1 4,2 4,3 4,4 4,5 4,6 4,7
5 — green −0.7071068 −0.7071068 5,0 5,1 5,2 5,3 5,4 5,5 5,6 5,7
6 — blue 1 0 6,0 6,1 6,2 6,3 6,4 6,5 6,6 6,7
7 — yellow −1 0 7,0 7,1 7,2 7,3 7,4 7,5 7,6 7,7
8 — orange −0.7071068 0.7071068 8,0 8,1 8,2 8,3 8,4 8,5 8,6 8,7
9 — brown −0.9238795 0.3826834 9,0 9,1 9,2 9,3 9,4 9,5 9,6 9,7
10 — yellow-green −0.9238795 −0.3826834 10,0 10,1 10,2 10,3 10,4 10,5 10,6 10,7
11 — pink 0 1 11,0 11,1 11,2 11,3 11,4 11,5 11,6 11,7
12 — blue-green 0 −1 12,0 12,1 12,2 12,3 12,4 12,5 12,6 12,7
13 — light blue 0.7071068 −0.7071068 13,0 13,1 13,2 13,3 13,4 13,5 13,6 13,7
14 — dark blue 0.9238795 0.3826834 14,0 14,1 14,2 14,3 14,4 14,5 14,6 14,7
15 — light green −0.3826834 −0.9238795 15,0 15,1 15,2 15,3 15,4 15,5 15,6 15,7

Sound capabilities[edit]

The TED featured a simple tone generator that produced two channels of audio. The first channel produced a square wave, and the second could produce either a square wave or white noise. Between the two channels you could hear either two tones or one tone plus noise. This tone generator was designed for business applications, and did not provide the extensive sound features found in the SID chip.

Other features[edit]

The TED includes three 16-bit interval timers, which consist of down counters operating at the master clock frequency. They can generate IRQs on underflow. The chip also contains an I/O port, which is used on the Plus/4 and 16 to scan the keyboard and joystick. In addition, it handles bank switching, used by the operating system to maximize the amount of RAM available to Commodore BASIC.

TED has a higher priority on DRAM access than the CPU. Thus in the borders the CPU is able to run at full speed, but in the active display area it is throttled down to half the clock rate. An undesirable feature of the chip is its well-known tendency to destroy itself through overheating. To preserve a computer which employs this chip in working order, it is recommended to improve its cooling.[3]

As TED chips are not produced anymore its internal architecture has been investigated and replicated by a hungarian developer called Istvan Hegedus using verilog HDL in a project called FPGATED.[4] The source code of this project has been made open source which lead to a C16 implementation on the MisTer platform and a working prototype drop in chip replacement by the original code developer.

There is another TED replacement in development based on the original source code by the "ThED project".[5]

Notes[edit]

  1. ^ "TED 7360 Data Sheet" (PDF). Commodore Semiconductor Group. Retrieved May 21, 2019.
  2. ^ Color values are taken from the source code to the YAPE Plus/4 emulator.
  3. ^ Bucci, Davide. "CPU and TED temperatures in a Commodore Plus/4". Retrieved May 21, 2019.
  4. ^ "FPGATED reimplement the TED chip of Commodore 264 series in FPGA". Retrieved May 14, 2022.
  5. ^ "ThED – MOS technology TED replacement for Commodore 264 series". Retrieved Oct 29, 2021.

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