Sunday, April 22, 2018

Java version of QIC-24 pulse decoding - Draft 01

According to Carlos G Mendioroz, who wrote these programs:

Ok, code is not clean at all, but with a little help it should be understandable...

It read the raw dump as 0/1 for sample and makes run length codes of periods (at rising edges). There is a class for doing the timing (finding the first long preamble and then resynching at preambles) and then some utility methods to follow the block structure, decode the gcr 4/5 and calculate CRC.

The main trick ended being variating the timing when an exception occurs and retry decoding a block. it tries -2, -1, +1 and +2 reference periods, which change the 0/1/2 run length boundaries.

Let me know if you need help understanding it. There is no output yet, but having a good CRC kind of proves the decoding of the block was ok (and the block id matching :)

Wednesday, May 11, 2016

DC600HC IOTAMAT Format Blank QIC Cartridge Analysis (HCD format)

Click here to download the .logicdata file that I display in my video above.

I see in the following doc, that there are a number of different "preformatted" QIC cartridges of this era:


Compatibility and Competitive
Cross Reference Information
Data Cartridge Tape Products 


Looks to be a 3M thing, since these are all their model tapes, and this is their publication.

Monday, April 18, 2016

Reading Zilog S8000 QIC Tapes (MFM format)

I've read a few tapes purportedly from the Zilog S8000 using a DEI drive, and a quick look at the data captures in the Saleae GUI appears to show an MFM format, but with the data block anatomy unknown at this time.

So that I can orient myself to the data pulses I see in these captures, I'm reviewing the 

It is believed that this is the drive that these tapes were written with.

Here's what the beginning of the first block looks like: