Televideo 912B
ROM's
Two ROM's, one in socket A3 and the other in socket A49.
Images of the two ROM's are at here (at the bottom, past the notes).
RAM
• Data RAM, comprising of two 2111 RAM chips, in sockets A52 and A53 ("read/write storage by the firmware")
• Display/character RAM, comprising of four 2114 RAM chips, in sockets A6, A8, A10 and A12
2111 Failure
NOTE: My terminal is in half duplex mode so that for these tests, typed keys appear on screen.
If the 2111 at A52 is the only RAM chip removed:
- At power on, a single beep is heard, and on the screen, only the cursor is seen (as expected).
- Pressing keys does not affect the display (just like a dead keyboard, or terminal in full duplex mode).
If the 2111 at A53 is the only RAM chip removed:
- At power on, a single beep is heard, and on the screen, only the cursor is seen (as expected).
- Pressing some keys result in a space on screen, some "o", some "?", some "/".
2114 Failure
NOTE: My terminal is in half duplex mode so that for these tests, typed keys appear on screen.
If the 2114 at A6 is the only RAM chip removed:
- At power on, a single beep is heard, and the screen at here is presented. Note that only part of the screen is affected. The display is stable.
- Typing keys results in unexpected characters appearing at the cursor position.
- If I use the arrow keys to move the cursor to an area of the screen where there are no characters, then typed keys result in the expected characters appearing on screen.
If the 2114 at A8 is the only RAM chip removed:
- At power on, a continuous beep is heard, and the screen at here is presented. The characters displayed are changing.
- Pressing keys does not affect the display.
If the 2114 at A10 is the only RAM chip removed:
- At power on, a single beep is heard, and the screen at here is presented. Note that only part of the screen is affected. The display is stable.
- Typing keys results in unexpected characters appearing at the cursor position.
- If I use the arrow keys to move the cursor to an area of the screen where there are no characters, then typed keys result in the expected characters appearing on screen.
If the 2114 at A12 is the only RAM chip removed:
- At power on, a continuous beep is heard, and the screen at here is presented. The characters displayed are changing.
- Pressing keys does not affect the display.