|Manufacturer:||Digital Equipment Corporation|
|Year Design Started:||January, 1972|
|Year First Shipped:||June, 1975|
|Word Size:||36 bits|
|Logic Type:||ECL ICs|
|Design Type:||clocked synchronous, microcoded|
|Microword Width:|| 75 (Model A)|
76 (Model B)
|Microcode Length:|| 1280 (Model A)|
2K (Model B)
|Clock Speed:||500 nsec|
|Cache Size:||2K words|
|Memory Speed:||1.0 μsec (initial core memory), 500 nsec (later MOS main memory)|
|Physical Address Size:||22 bits|
|Virtual Address Size:|| 18 bits (Model A and B)|
23 bits (Model E)
|Memory Management:||paging, 512-word pages|
|Operating System:||TOPS-10, TOPS-20, ITS, WAITS, TENEX, TYMCOM-X|
|Price:||US$250K (CPU), US$600K-1.2M (system)|
The CPU had two main units, the 'E Box' ('Execution') and the 'M Box' ('Memory'). It provided three types of busses to the rest of the components of the system; the 'E Bus', from the E Box; and the 'S Bus' ('Storage'), and later the 'C Bus' ('Channel'), from the M Box. The S Bus was for the attachment of main memory units, while the C Bus allowed DMA accesss to main memory.
A KL10 could support up to 4 DTE20 Ten-Eleven Interfaces; they allowed connection of a PDP-11 front end. At least one PDP-11, the 'master', was required; it could bootstrap the KL10, including loading the microcode.
A DMA20 Memory Bus Adapter could be attached to the S Bus, to provide a KI10-compatible external memory bus (called the K Bus in the KL10). Similarly, an DIA20 In/Out Bus Controller could be attached to the E Bus, to provide a PDP-10 I/O Bus (called the I Bus in the KL10).
Up to 8 RH20 MASSBUS controllers could be installed; they connect to the E Bus (for control), and also to the C Bus (for data movement). The MASSBUS can be used to connect a variety of disk and magnetic tape mass storage devices.
- NIA20 Network Interconnect Adapter - an Ethernet interface
- CI20 Computer Interconnect - interface to the CI high-speed link
If either the NIA2O or CI20 in installed, since they use some of the backplane slots for the RH20's, only 4 RH20's may be installed if either is installed. They also connect to the EBUS and CBUS.
There were two main packaging families: those used for the DECsystem-10, which used tall, medium-width cabinets like those of the KA10 and KI10, in the same turquoise blue as the latter; and the DECSYSTEM-20, which were shorter and wider and painted cream and orange.
The CPU, front end, and I/O controllers were accommodated in a set of three racks (or four, for some DECSYSTEM-20s); one to hold the CPU, one for the front-end, and one for all the I/O. The E Box and the M Box were both on the main backplane, in the CPU cabinet. The DMA20, DIA20, DTE20s and RH20s were all accommodated on backplanes in the second, I/O, cabinet; the first two were on a single backplane, and the latter two on another.
There were a number of variants over the lifetime of the KL10; the situation is confusing because there appear to be three different, somewhat orthogonal, namespaces for KL10 variants:
- CPU hardware variants (-PA, -PV and -PW);
- informal internal names for CPU variations ('Model A', 'Model B');
- KL10 'models' (-A through -E, and -R).
As far as is known, 'Model A' is an internal aphorism for -PA, and 'Model B' for -PV; the two are described in a DEC document as:
- "KL10-PA - A basic ECL processor with slots for cache and internal channels. Unofficially .. referred to as the Model A machine."
- "KL10-PV - A KL10-PA which has been modified to include extended addressing, more extensive microcode, and a faster clock. Unofficially .. referred to as the Model B machine."
The KL10-PV supported the 'Extended' PDP-10 architecture, with support for multiple 'sections' (256K-word address spaces), available to both the kernel and the user (although apparently only TOPS-20 supported the latter). The earlier machines could be field upgraded to a -PV, but it apparently needed a modified/new backplane.
Substitution/addition of the later MCA25 KL Cache/Paging Upgrade, which increased both the size of both the main memory cache, and the paging cache, as well as improved the functionality of the latter, produced the -PW. It too required backplane modifications; the resulting machine was termed the 'Model C' by some.
Many of the 'models' (e.g. 'KL10-C' and 'KL10-D') appear to be names for particular configurations (with various options, such as the DMA20 and DIA20); here is a DEC table which (hopefully authoritatively) defines them:
|Model||PV||Cache||Int Chans||Max DTEs||Max RH20s||DIA||DMA|
(*: Maximum 4 RH20s if a CI20 or NIA20 is installed, as those use the slots for RH4-7 in the RH20 backplane.)
The 'KL10-R' appears to be a Model E in a new cabinet design, one compliant with newer FCC RFI emissions standards; but it may also refer to systems with the MCA25.
Note that the early KL10-A only supported a single DTE20, and no RH20s, and it was the later KL10-B and up (the first two also with the Model A CPU), which supported up to 4 DTE20s and up to 8 RH20s. This is because the I/O backplanes in the second bay of the CPU differed in the KL10-B and up, to support the larger I/O configuration. (The DTE20 backplane differed between the two.) The KL10-A was intended to replace KA10 and KI10 processors, hence the lack of support for RH20s, etc.
One significant division between KL-based systems is between those with an external memory bus, and those with an internal memory bus (the native S Bus).
The DEC numeric model numbers - a fourth namespace - are even more confused, since a 1090 could be either a "KL10-B(PA) or KL10-D(PV)"; similarly, the 2040 and 2050 could be a "KL10-C(PA) or KL10-E(PV)".
The SAIL (or SU-AI) timesharing system — WAITS — main computer was a KL10 from 1976 to 1991. In 1983, it was upgraded from a model A to a model B CPU. Near the end, failing isolation in the backplane was fixed by inserting toothpicks.
- KL10 - documentation at Bitsavers
- Digital's DECSYSTEM-20 - Part 5 - CPU (KL10)
- Corestore collection: DECSYSTEM 2065 KL10-RH - Good images, has two MG20 memory units
- KL10 I/O connectors - Good image of bus connectors: on the bottom, MASSBUS connectors on the left; memory and I/O bus QuickLatch connectors on the right
- KL-10D Module Utilization
- ITS microcode