Last Updated: November 09, 2005 09:48:34 PM
Rev. A of the 1861/Keyboard card. The card interfaces to a PS/2 keyboard and uses a standard 1861 setup to drive a composite monitor. Currently the 1861 circuit is untested. The connector at the bottom is from the CPU card and provides some signals required by the 1861 that are not on the standard bus. On System-4 the keyboard interface was contained on the CPU card.
The board has several subsections: I/O decoding logic (borrowed from Mile Riley’s ELF), serial to parallel keyboard interface made of a PAK-VI and a PIC 16F84 processor, 1852 based parallel input port, and 1861 video circuit. Jumper blocks select I/O port used by keyboard and 1861. The PAK-VI chip at the top of the card is a PS/2 to ASCII decoder produced by AWC Electronics.
|Jan. 12/2005||Test 1861 Circuit|
Schematics, board layout, and operational description
|Revision||Production Date||Schematic||Layout||Operational Description||PIC Code|