Abstract: Inviable T4 phage-like particles capable of directing the expression of large non-T4 DNA fragments from T4 expression control sequences are produced. Thus, E. coli harboring pBR322 derivatives containing cloned T4 gene 23 DNA sequences were infected with T4 phage carrying a deletion of the denB gene. Homology-dependent recombination results in the production of inviable phage-like particles containing DNA molecules composed of multiple, tandemly repeated copies of entire plasmid molecules covalently linked to single copies of normal phage genes. The yield of these inviable particles, intially low, was increased by means of a reiterated infection process that involves the use of a cloned T4 origin of replication. When T4 gene 32 expression control sequences linked in proper orientation to a DNA sequence coding for the non-T4 protein .beta.-galactosidase were also cloned in one such pBR322 derivative (pVH773), inviable phage particles capable of directing the synthesis of enzymatically active .beta.

Abstract: Inviable T4 phage-like particles capable of directing the expression of large non-T4 DNA fragments from T4 expression control sequences are produced. Thus, E. coli harboring pBR322 derivatives containing cloned T4 gene 23 DNA sequences were infected with T4 phage carrying a deletion of the denB gene. Homology-dependent recombination results in the production of inviable phage-like particles containing DNA molecules composed of multiple, tandemly repeated copies of entire plasmid molecules covalently linked to single copies of normal phage genes. The yield of these inviable particles, intially low, was increased by means of a reiterated infection process that involves the use of a cloned T4 origin of replication. When T4 gene 32 expression control sequences linked in proper orientation to a DNA sequence coding for the non-T4 protein .beta.-galactosidase were also cloned in one such pBR322 derivative (pVH773), inviable phage particles capable of directing the synthesis of enzymatically active .beta.

Abstract: A data processing arrangement including a microprocessor and a plurality of input/output devices arranged in groups in accordance with a predetermined priority scheme. Each input/output device is capable of initiating a service request via an interrupt line to the microprocessor as a result of which a machine cycle is initiated by the microprocessor in which control signals are produced by the microprocessor and applied to logic circuitry coupled to the groups of input/output devices. The logic circuitry operates to propagate a low voltage level at the output of the input/output device initiating the service request down through the lower priority groups and to change inputs of the lower priority input/output devices from normal high voltage levels to low voltage levels. Data is then applied by the input/output device initiating the service request to the microprocessor, following which a microprocessor reset instruction resets the device.