Host Transfer (Nonstandard) DLP

The Host Transfer (Nonstandard) DLP is used to connect a Medium System or V Series system to the B9383, B9384, B9385 and B9387 microprogrammed disk pack drive controllers. The nonstandard version of the Host Transfer DLP supports an interleaved layout of sectors on a track providing increased capacity (albeit with less throughput).

The Nonstandard Host Transfer control was named in retrospect. It was the original* Host Transfer (or disk control) DLP and was designed in Pasdena. A year or two later the Large Systems plant in Mission Viejo began using DLPs on their systems and needed some features in a disk control that the current Host Transfer DLP did not support. Since they were Large Systems, they naturally named their new control as the Standard Host Transfer control, relegating the original design to Nonstandard. V Series eventually used both forms of Host Transfer control and several other forms of disk control. None of them have particularly common Command or Result Descriptor formats with any of the others, making one wonder somewhat about the use of the term Standard. The Large Systems Standard Host Transfer control became known as the Sequential Host Transfer control, since it was not capable of interleaved disk layout.

* It was actually the second attempt at a host transfer control. The first was designed by a junior engineer with insufficient supervision, and was a complete failure. It was respecified and redesigned by a senior engineer in a great panic when it became obvious that the first version could not be made to work.

Operation Speed
READ 8 megabytes/second
WRITE 1 megabytes/second

(The Host Transfer (Sequential) DLP was designed to address the write performance issues with this DLP).

DPDC I/O Descriptors

Operation SYS OP MLI OP S L1 L2 L3 Addresses Used?
READ 50 8
Data/(EPC Enable) * 0 0 U A-B, C Yes
Data/(EPC Disable) * 0 1 U A-B, C
Unit ID * 0 2 U A-B, C* Yes
Memory * 0 4 U A-B, C*
Absolute * 0 8 U A-B, C
Subsystem Poll * 0 E 0 A-B, C ?
WRITE 52 4
Data * 0 0 U A-B, C Yes
Initialize * 0 8 U A-B, C Maint
Initialize
(Data Field Only)
* 0 A U A-B, C Maint
Host Load * 8 0 0 A-B, C Yes
TEST 54 2
Unit * 0 0 U A-B*, C* Yes
Power Unit Down * 0 2 U A-B*, C* Yes
Power Unit Up * 0 3 U A-B*, C* Yes
Controller Lock Disable * 0 4 0 A-B*, C* Yes
Controller Lock Enable * 0 5 0 A-B*, C* Yes
Verify (EPC Only) * 0 6 U A-B, C Maint
Verify (EPC & Data) * 0 7 U A-B, C Maint
Leave Maint Mode * 0 8 U A-B*, C* Maint
Enter Maint Mode * 0 9 U A-B*, C* Maint
Relocate * 0 E U A-B, C Maint
ID * C 0 0 A-B, C* ?

U designates unit number.

Commands marked “Maint” are not used by the MCP, but are used when reformatting a diskpack.

* The A-B buffer address pair is not required on most Test operations, but because the op format is required to be 54, a valid address pair must be supplied. Typically 0/4 is used.

The C address is not required on many Read and Test commands, but because of the command format used (50/54) a valid C address field must be supplied. Typically 8 digits of zeros are used.

Command Formats

4X series system opcodes have two addresses. The A and B addresses are the start and end of the memory transfer buffer. Some operations do not transfer any data other than the command and result descriptors. The A and B addresses are typically set to 0 in this case.

5X series system opcodes have three addresses. The A and B addresses are the start and end of the memory transfer buffer. The C address contains 8 digits of extra parameters for the command. In this case the first 6 digits are the disk sector address in decimal.

The Nonstandard Host Transfer Control will only accept 5X series command formats, 4X commands are arbitrarily rejected.

Read Unit Status

Unknown at this time.

Host Transfer (Nonstandard) DLP Result Descriptor Word 1

A B C D
8 CONTROLLER
NOT
READY
TIMEOUT SUCCESSFUL
RECOVERY
CONTROLLER
LOCKED
4 DESCRIPTOR
ERROR
HD-DDP
VERTICAL
PARITY
ERROR
WRITE
LOCKOUT
CANCELLED
2 VERTICAL
PARITY ERROR
(MLI)
HD-DDP
LONG-
ITUDINAL
PARITY
ERROR
SEEK
INITIATED
ZERO
1 LONGITUDINAL
PARITY
ERROR
(MLI)
DRIVE
BUSY
ZERO ROM
COMMAND
ERROR

Host Transfer (Nonstandard) DLP Result Descriptor Words 2 and 3

R/D Bits
Word 2 Word 3
A B C D A B C D
Description 8421 8421 8421 8421 8421 8421 8421 8421
Data Error 1111 0000 Sector Address
Seek Error 1111 0001 Sector Address
Address Error 1111 0010 Sector Address
Write Retry 1111 0011 Sector Address
Read Retry 1111 0100 Sector Address
Data Error Correct. 1111 1000 Sector Address
Command Error (B) 1111 1000 Sector Address
Command Error (A) 0000 R/D Tag Command
Disk Error 0001 R/D Tag Disk DDP Status
Disk Error 0100 R/D Tag Disk Unit Status
Disk Error 0101 R/D Tag Drive Msg Word 1
Host Error 0110 R/D Tag Host DDP Status
Processor Error 1001 R/D Tag Memory Status
Controller Failure 1010 R/D Tag Not Used
Exchange 0 Failed 1011 R/D Tag 0000 0000 0000 0000
Exchange 1 Failed 1011 R/D Tag 0001 0000 0000 0000

Host Transfer (Nonstandard) TEST/ID Result Descriptor Word 2

A B C D
8 0 0 X X
4 0 0 X X
2 0 1 X X
1 1 0 X X

X - field installed jumpers (not used for medium systems)

Each Host Transfer DLP can be jumpered with a specific code. This code is not used by the V Series MCP and is typically left unjumpered, returning a value of 00. (This feature was implemeted for the Large Systems MCP.)

dlps/host_transfer_nonstandard.txt · Last modified: 2012/02/04 15:29 by scott
 
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