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1220: Difference between revisions
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The 1220 is built around a 65C02 as the control processor with 48K of SRAM, and 64K of firmware in a bank of EPROMs. There is a separate board under it that manages the display and keypad, which is powered by another 65C02 CPU and is using an MC68A45 CRT controller to drive the display. The display board has 56K of RAM and 8K of ROM, with two coin cell batteries to retain settings. There is a bug that prevents the 1225 from keeping the date after the year 2000. Upon powering it off and on again it will revert to 19xx, e.g. 2018 will turn into 1918. | The 1220 is built around a 65C02 as the control processor with 48K of SRAM, and 64K of firmware in a bank of EPROMs. There is a separate board under it that manages the display and keypad, which is powered by another 65C02 CPU and is using an MC68A45 CRT controller to drive the display. The display board has 56K of RAM and 8K of ROM, with two coin cell batteries to retain settings. There is a bug that prevents the 1225 from keeping the date after the year 2000. Upon powering it off and on again it will revert to 19xx, e.g. 2018 will turn into 1918. | ||
The keypad switches have a tendency to become very "bouncy". See the page on [[Restoring 1220, 1225 and 1230 keypad|restoring the 1220, 1225 and 1230 keypad]] for details. | |||
===Easter egg=== | ===Easter egg=== | ||