dark hole in the delicate phosphor in well under a minute; programmers had to be ready to hit the Stop lever fast if a very bright spot suddenly appeared because of a programming mistake. Teletype output Printed output on a Teletype Model 33 ASR was controlled by a single pole relay. A subroutine would convert the LINC character codes into ASCII and use timing loops to toggle the relay on and off, generating the correct 8-bit output to control the Teletype printer. Laboratory interface The LINC connector module included bays for two plug-in chassis allowing custom interfacing to experimental setups. Analog-to-digital and digital-to-analog converters were built into the computer and each could be accessed by a single machine instruction. Six relays were also available. Variants In addition to the original "classic" LINC, slight programming variations occurred when using the micro-LINC (μ-LINC) (1965), micro-LINC 300 (μ-LINC 300) (1968) (integrated circuit [MECL] versions), and LINC-8. There were variations in the input/output equipment, access to memory. Later models had a faster clock speed. LINC-8 and PDP-12 computers While Bell in his book says designing the LINC provided the ideas for DEC's second and third machines, the PDP-4 and the PDP-5. Digital Equipment Corporation would launch the extremely successful PDP-8 before it manufactured the first next-generation LINC-compatible computer, the LINC-8 and a combination PDP-8/I and LINC, combined as the PDP-12. DEC's final 12-bit lab machine, the Lab-8/E, incorporated the LINC instruction set. The first follow-on, the LINC-8, booted (slowly) to a PDP-8 program called PROGOFOP (PROGram OF OPeration) which interfaced to the separate LINC hardware. The PDP-12 was the last and most popular follow-on to the LINC. It was a capable and improved machine, and was more stable than the LINC-8, but architecturally was still an imperfect hybrid of a LINC and a PDP-8, full of many small technical glitches. (For example, the LINC had an overflow bit which was a small but important part of the LINC's machine state; the PDP-12 had no provision for saving and restoring the state of this bit across PDP-8 interrupts.) MINC-11 computer Digital produced a version of the PDP-11/03 called the MINC-11, housed in a portable cart, and equipable with Digital-designed laboratory I/O modules supporting capabilities such as analog input and output. A programming language, MINC BASIC, included integrated support for the laboratory I/O modules. MINC stood for "Modular Instrument Computer." The name undoubtedly was intended to