TQK50 — TMSCP tape controller with TK50
The TQK50 is DEC’s controller for the TK50 cartridge tape. It speaks TMSCP,
the tape dialect of MSCP, through the same two registers and command and response
rings as the UDA50 disk controller, and QUniLator builds it on the
same MSCP port. Each TK50 drive behind it holds a tape image in SIMH’s .tap
format. It is listed as tqk50, of type TQK50, with four drives tqk500 to
tqk503, and ships disabled.
What the machine sees
Section titled “What the machine sees”| Registers | IP at 774500 and SA at 774502 (17774500 and 17774502 on a QBone) |
| Interrupt | BR5, at the vector the host gives the controller when it initialises it |
| Transfers | Commands, responses and data move by DMA to and from the host’s memory |
| Drives | Four TK50 units, 0 to 3. A unit without a tape is reported as not available |
| Identity | Controller class 1, model 9 (TQK50) |
| Tape | Records and tape marks, read, written, spaced over and rewound. A cartridge holds 94 MB, set by the drive’s capacity |
When a command leaves the tape past capacity, the drive reports end of tape
once for that crossing, which is the signal a host writing a full tape turns
around on. A write that reaches the end also latches a serious exception, which
the host clears before it carries on.
Using it
Section titled “Using it”- Enable
tqk50on the Configurations screen. - Set a drive’s
imageto a.tapfile and enable the drive. A tape that does not exist yet is created empty; an image file without write permission mounts write-locked, and the drive’s WRITE PROTECT lamp lights. - The host brings the unit online and uses it. Changing the image unloads the tape and takes the unit offline.
The drive writes straight into its image file. A tape that has to stay as it is belongs in a file without write permission.
A smaller capacity models a shorter tape, which bounds the run time of a
diagnostic that writes the whole cartridge.
What has been verified
Section titled “What has been verified”- DEC’s TKxx data reliability diagnostic CZTKBD0 runs under XXDP on a QBone pass after
pass with 0 errors: it fills the tape to the end, reads every record back and
compares it. The runs used a shortened
capacity.
Parameters
Section titled “Parameters”It has no parameters of its own.
It also carries the parameters under parameters every MSCP controller has.
On this device, base_addr can be set.
Drive parameters
Section titled “Drive parameters”Status
Section titled “Status”What the device reports as it runs. A configuration does not store these.
| Parameter | Short | Value | What it is |
|---|---|---|---|
writeprotectlamp | wpl | 0 or 1 | State of WRITE PROTECT lamp |
It also carries the parameters under parameters every drive has.
On this device, capacity can be set.
In detail
Section titled “In detail”writeprotectlamp
Section titled “writeprotectlamp”The drive’s WRITE PROTECT lamp: lit while the cartridge is write-locked, because its image file is read-only or the host has locked the unit in software. The dashboard shows it beside the ACCESS lamp, accesslamp, which lights while the tape moves or transfers.