Mostek VAB-2 Video Terminal

• 1978 3870 F8 Microcomputer Data Book - bitsavers.org
• 1980 Mostek Circuits and Systems Product Guide - bitsavers.org
• mostek vab2 - PDF copy of the specific section from the 1978 Mostek catalog on the VAB-2
• 1977 Mostek VAB-2 Video Adapter Board Operation Manual - PDF copy of a manual I had found, scanned and posted on archive.org

The VAB-2 photos in the 1978 catalog matches the board seen in this terminal, the power supply section on the far left was broken off from the main board and mounted near the keyboard. The only identifying markings seen on the VAB-2 board is "Mostek ASSY 450-00189-00" that matches the image in the VAB-2 operation manual. The 3870 was a 8-bit microcontroller complete with ROM and RAM. The microcontroller decoded the keyboard, handled RS-232 serial communication and generated NTSC video output. This terminal was built in a kit-style steel keyboard case that was manually drilled or cut out to accomodate this particular keyboard, switches and connectors. There is a BNC connector for video output and a DB25 serial connector carrying 300 baud serial 8-bit data with 1 stop bit. The Mostek board was advertised with only two baud rate options: 110 or 300. The display could show 16 lines of 64 characters in both upper or lower case.

I acquired this homemade terminal in the mid-2000s from the same engineer who had given me the late 1970s Tektronix computers and hardware. I thought it was a curious little video terminal built around a seldom-seen commercially available board and thought the board was originally designed to be used in something else. I could not figure out exactly what it was until about 20 years later when I came across PDF copies of the Mostek product catalogs. I last tested it in 2025 and it still works displaying video on a flat screen TV. The characters on the screen are simple and look similar to the TV typewriter/terminal implementations seen in the mid-1970s.