Improved TS2068 Internal ROM Bypass

Publication: Timelinez
Pub Details: Timelinez v7 n7-12 (Volume 7, Issue 12)
Date: July-December 1989
Pages: 1

Detailed hardware design for replacing the TS2068’s HOME ROM and EXROM without opening the computer case, using the cartridge slot to intercept the bus enable (BE) signal. Three designs: HOME ROM bypass (Figure 1) using BE-driven suppression of ROMCS in combination with external ROM/RAM; EXROM relocation (Figure 2a) by physically remounting the chip with full address decoding on an external board; and an advanced EXROM bypass (Figure 2b) using a latch circuit. Bypass board features include full rear connector pass-through, dual ROM sockets (RAM for development, EPROM for production), write-protect switches, jumpers for battery backup removal, and optional RGB video output. Includes complete circuit schematics and a short BASIC program to copy HOME ROM and EXROM to the bypass board. Declares the design public domain through The WIDJUP Co. Also includes a special message to DOS/mass-storage manufacturers about OS compatibility requirements for bank switching.