CVAX

CVAX is a chipset that was developed by Digital Equipment Corporation ( DEC) 1984-1987, and in such order, and the Virtual Address eXtension ( VAX ) has been implemented. The chipset was designed exclusively Model 6000 2/3 used in DEC MicroVAX computers as 3400, MicroVAX 3100 Model 10 /20 or the VAX and was not available for other computer manufacturers. The 32- bit microprocessor chip was included in the first processor by DEC which included an internal processor cache. In order to save chip area, the one KiByte large cache for data and program code of the dynamic RAM cell was realized, which is only one field effect transistor per bit.

Construction

The chip set consists of a 32 -bit microprocessor ( CPU CVAX 78034, 21-24674 ), which can be clocked at up to 12.5 MHz, a floating point unit, which is referred to as a floating point accelerator ( CFPA, 21-26604 ), a clock chip CVAX clock chip and various peripheral chips like the CVAX system support chip ( CSSC ), CVAX Memory Controller ( CMCTL ) and the CVAX Q- bus interface chip ( CQBIC, 21-25972 ).

The CVAX 78034 CPU consists of approximately 134,000 field-effect transistors on a chip area of 9.7 mm by 7.4 mm. The processor of DEC was manufactured in a CMOS process with a structure width of 2 microns. It is accommodated in a chip housing CQFP -84. The processor is controlled by a micro-code and has a partial pipeline. The calculator includes 16 general-purpose 32 bits wide registers. It can be a physical memory size of 1 GiByte and a virtual address space of 4 GiByte be addressed.

The first executed as a separate chip floating point ( CFPA ), which is connected directly via a special interface to the CPU CVAX, consists of approximately 65,000 field-effect transistors on a chip area of 7.3 mm by 9.1 mm. The CFPA is optimized for floating-point operators, such as multiplication and division.

Shortly before the start of mass production CVAX chipset in late 1987 was a presented in the structure width to 1.5 microns smaller version. This CVAX as or as CVAX designated 60 chipset could be operated at a higher clock rate of just over 16 MHz and was used in subsequent years in the then new VAX 6200 multiprocessor computers. The last adjustment to the chipset was the integration of the CFPA and the CVAX clock chip with a 8 KiByte L2 cache in a chip in 1990.

Special

On the CVAX 78034 CPU semiconductor chip different, technically unnecessary symbols and texts have been placed by the development team. These items are only visible after the mechanical and chemical removal of the die housing by means of thin section and microscopic examination techniques of the chip surface. Among other things, the representation of a hand in the poker game with the english text $ ... The Dream Is Always The Same was attached to the semiconductor chip. This expressed the wish to be able to boot the OpenVMS operating system and to get the command prompt, which announces itself with a $ sign appears.

At the time some semiconductor chips in the former Eastern Bloc were analyzed and reconstructed ident, also referred to as reverse engineering. While the predecessor chipset MicroVAX 78032 was still successfully copied by DEC as MME U80701 in the former GDR, this was due to the contemporary historical processes with the collapse of the Eastern Bloc in the CVAX chipset no longer possible. The planned as U80900 in the GDR replica of CVAX 78034 was never realized.

Since it was aware on the manufacturing side of the replicas in the Eastern Bloc, a text was on the chip area of ​​the CVAX 78034 filed in Russian with Cyrillic characters, which states something like: VAX - If you're good enough to steal the best.