This is a description of the original CBM IEEE-488 cartridge "VIC-1112" for the VIC20, and of the following files: README - this text schematics.ps - schematic diagram (PostScript) schematics.tif - schematic diagram (TIFF) 325329-04.bin - EPROM (4 kB, raw binary) I've drawn the schematics from my own 2 IEEE-488 modules. The print on the board is "P/N NO. 1110009 REV.A", "COPYRIGHT 1981". U1: M53217 or 7417, 6 buffers (open collector). 2 are used to drive the lines EOI and IFC of the IEEE-488 bus, the other 4 are free. U2: EPROM 2516, 2 kB, label "325329-04", or ROM "325329-03" (same contents). U3: 74LS00, 4 NAND gates, all used. U4, U5: MOS 6522 VIA U6, U7, U8: MC3446, quad driver / receiver for IEEE-488 General Purpose Interface-Bus (GPIB) The ROM / EPROM is located at $B000 ... $B7FF. No autostart. Start with SYS 45065 (= 11*4096+9 = $B009) The VIAs are located at $9200 ... $920F (U4) and $9210 ... $921F (U5). july 1999, Wolfgang Guenther (woll@informatik.uni-bremen.de)