| 摘要 |
The video control circuit displays the standard fonts supported by the character code and various type characters by using the remainder attribute code on a CRT screen. The circuit comprises a selection logic (107) connecting to CPU (102), a special font character producer (201) connecting with the output terminal of an attribute code buffer latch (108), an attribute decoder (205) serially connecting with the existing attribute decoder, a multiplexer (206), a shift register (202) connecting with a timing control circuit (104) and the special font character producer, an enable logic (203) connecting with the shift register and the selecting logic, and an OR gate (204). Two attribute decoders and the multiplexer are implemented by a programmable array logic.
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