PmWiki | Emulator / TD8E

Class: TD8E, Dectape

TU56 Control emulation

This is how the TU56 looks in my emulator. I think it is quite realistic.

The tape reels move and the tape is rolled in the reels transparently so that one can see how far it has taken up.

Set switches remote and write-enabled when accessing tapes which are selected by right-clicking on the window. In the popup Menu one can mount tapes and set the format enable switch.

The format .pxg tapes is based on the following:TD8E Pauler. As shown here my format (PxG) keeps the mark track as the most significant bit of a nibble. The three lower bits are the corresponding data bits of this line. Then two lines are packed into one byte.

A Java program to make .pxg tapes is: ConvertTape : It can be used to transform 128W/blk files to my format, to transform the data coming from my PDP8 and also to format new blank tapes. This program illustrates the format and the relation to .djg formats.
The program used to dump Dectape data on my real PDP8 is shown here: Dumptd8e Pal Source

Program Name	Maindec	Remarks
TD8E Dectape Diagnostic	MAINDEC-08-DHTDAA-TD8E-Test	Original Test Program: DHTDAA.SV on disk
TD8E Dectape Diagnostic	MAINDEC-08-DHTDAD-TD8E-New-Test	Rewritten Source without comments: DHTDAD.SV on disk
TD8E Copy program	DEC-8E-UTDEA-TD8E-Copy	TDCOPY.SV on Disk
TD8E Formatter	DEC-8E-EUZC-TD8E-Formatter	TDFRMT.SV on disk

The papertape and listing of DHTDAA were incompatible, that is why I wrote a new source DHTDAD that conforms.

In order to test the TD8E Dectape you will need two blank tape files. Create these with our Java program to make .pxg tapes: ConvertTape. This program also illustrates the .PXG format.
Boot the PDP8 with the Build-11-03-07 from Disks.Working m43 volume, then mount the first tape file on unit 0 and the unit 1 to local. Then start the test program (DHTDAA.SV or DHTDAD.SV) from the Myprogs disk. Now follow the next steps for the rest of the test.

Switch	Function
....	Mount tape on unit 1
....	Set write enable on both units
0201	Set switch register and load address
0000	Clear switch register
....	Press continue for rest of test
....	until PASS 0001 COMPLETE (3 minutes full speed)

This means that my emulation is compatible with the whole TD8E diagnostic without any errors!

With the same tapes already mounted start the test program (TDCOPY.SV) from the Myprogs disk. Now follow the next steps.

Question	Answer
Highest field available:	7
From unit:	0
To units:	1
First input block:	...
Verify output:	1
Repeat:	0,^C

The original program tried to do a simultaneous rewind of both tapes. This does not work in my emulator (and a real TD8E will often run of the reels). A small patch (1362/5325 5354) was incorporated that allows the rewind of one tape after the other. Apart from this the TDCOPY program runs perfectly.

For using the formatting program (TDFRMT.SV) from the Myprogs disk follow the next steps.

Question	Answer
UNIT?	0
FORMAT?	MARK
0201 WORDS, 2702 BLOCKS. OK?[YES OR NO]	YES
SET SWITCH TO WTM	Remove tape 1,Format PDP8(WTM on)(Menu Dectape)
Are you sure to format an old file(Message on Dectape)	YES
SET SWITCH TO OFF	Write data (WTM off) (Menu Dectape)

A good starting point for using the emulator is to mount the disk Build-11-03-07 from Disks.Working on unit 0 Fixed. The tests used are located on disk MyProgs-22-04-07 of Disks.Working in .SV format and can be mounted on unit 0 Removable. Go to Disks.Working and download to a directory of you choice. You can then always mount these disks from this location. Don't forget to write-enable this directory and all of its files!