Processor Technology Sol-PC, Руководство пользователя

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Figure 8-5. 6574 Character Generator ROM pattern.
"C" and "T" were stored in the RAM in the proper character positions
in the third character row.
After the first two character rows have been displayed, the
Scan Counter (U40) is reset to a binary count of 15 (1111) and the
Character and Line Address Multiplexers (U30, U32 and U12) call up
the "C" in the Display RAM. The Scan Counter output specifies line
15 in the Character Generator ROM on RSI through RS4. As previously
mentioned, this line in the ROM is blank. Thus, the first scan line
of the third character row is blank.
The 7-bit ASCII code for the "C" (1000011) is input from the
Display RAM to address the Character Generator ROM by way of the Dat.
Latches (U26 and U27). This address is applied to ROM inputs A7
through Al (A6 through A0 in Figures 8-5 and 8-6). The Scan Counter
changes to a count of zero which specifies scan line R0 in the Chara'
ter Generator ROM. As shown in Figures 8-5 and 8-6, the ROM in turn
outputs a 7-bit word, 0011110, on D6 through D0 respectively (B7
through B1 on the schematic).
VIII-30
PROCESSOR TECHNOLOGY CORPORATION
Sol THEORY OF OPERATION SECTION VIII