Friday, June 30, 2023

Universal QIC Reader at VCFSW 2023 on IBM 5100 tapes

Thanks to Steve Lewis for this write-up...and for allowing me the opportunity to analyze the tapes of the IBM 5100!

In the words of Steve Lewis:
As things settled down a bit Sunday afternoon, I got time to catch up with AJ of Forgotten Machines (here). I had come across some original IBM 5100 tapes (off eBay) that, as far as I’m aware, aren’t archived anywhere. Before attempting to load them on a physical drive, we hoped to find an expert to help improve our odds (such as by digitizing the content and attempting to read it on new media). And AJ was up for trying!

AJ has a kind of “Uncle Fester from Addams Family” persona, which I mean in a very positive way (very energetic). AJ was using his own custom homebrew equipment that we jokingly called “Doc Brown Style” (ironically, the actor Chrispher Lloyd played the character Uncle Fester in one of the Addams Family movies – and also played as Doc Brown in the Back to the Future series).

AJ showed how he is able to fully control upper and lower heads of his “universal QIC reader” device (that he designed and built), to seek out data within tracks. The DC300 tapes used in the IBM 5100-series, and Tektronix systems of around those same year, used a 2-track system as opposed to the more elaborate 9-track tape systems. But finding the exact track positions requires a specialized device, which is exactly what AJ has built. Getting insight into this process was great – and we think that we did find and record a session of data. But VCF Staff was getting exhausted and security had to close up the building – we’ll resume this work over the coming months!

Saturday, January 28, 2023

Faster recovery service for QIC-150 and QIC-525-format tapes

I recommend:

He has better equipment than I generally do, for more "standard" tape formats that do not need special reverse-engineering.  He simply has the right equipment and knows how to use it.

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: