How to dump a rom with Audacity

Old computers used audio to “record” programs and data on audio cassette recorders. Kai Christian Bader, a German, used the audio out port from his Sharp PC-1500/1600 to send the data from the old computer to a new one and recorded the audio with Audacity:

In Audacity, he saved the recording as unsigned 8 bit PCM wav and afterwards, used wav2bin to convert it to the ROM image he wanted from the old computer.

Good to know. We had a DEC PDP-11 controlling the television transmitters where I used to work. Its code came on broadcast audio cartridges rather than cassettes. At the time the station (and FM upstairs) was crawling with players—and recorders.

I’m callin’ it 1981.


The PDP11-93 was the first serious computer I worked on. Rock solid. Later we got PC’s and the trouble started. First IBM PC-G, later Compal. The Compals were a bit faster, but also a bit buggier. Then we got Windows… :open_mouth:

Fortunately, we could find reasons to make the company buy Mac plusses for graphical stuff. So the PC’s went.

The PDP stayed. It was running RSX, a strange mixture of PC/M and Unix. And GEM, a graphical environment that was just too early. Never ever crashed. Had something like 4 MB of ram, which was an awful lot, way back then.

It could take up to 16 terminals. VT220. We only had five of those and one VT100 as console. It was the fastest and also the last PDP11. A couple of years later, DEC went bust.

A couple of years later, DEC went bust.

See? They should have made unstable computers with poor graphics and they might still be around.


The “naked” PDP11 was around 20.000 $. The IBM PC-G was around 5.000 $ and came with a keyboard.

DEC misjudged the market. By the time they were thinking about a “PC”, the clones already had grabbed it.

The same is happening to Intel. They figured the X86 platform would last forever and their only worry was keeping AMD alive. Now the ARM has conquered the world. The profit from on ARM processor is minute, compared to an X86, but the numbers are much, much higher.

And you can’t buy and close the competitor, as Intel usually does. There’s just too many…

The Project leader for RSX-11M was the great Dave Cutler - who went on to lead the VMS development for Vaxes - and then moved to Mictosoft to work on Windows NT. :nerd:

I worked as a developer using RSX-11M and then VAx/VMS before moving to DEC as a presales software specialist (specialising in operating systems) - great machines to work on they were,

And that got me my redundancy :frowning: :cry:


It’s a small world, isn’t it?

Nice to know.

I wouldn’t mind “finding” a PDP11 like we had in those days. You can interface it with almost any other computer. I think that would even work with TCP/IP today. We had an APE box going to the 3090. Yes, it was really called “APE”, that was Advanced Products Engineering. Small Belgian company. Whatever you needed to interface, that box did it. Inlcuding EBCDIC and protocol conversions, of course.

I’ll check my hardware archive (car-park/garage).



The latest models of the PDP11 line are the smallest. You’d think there would be some left, but I’m afraid there are more of the big ones and the vaxes left. And these are way too big for my man cave…

And I’ve sold all the vintage junk about a year ago. Someone wouldn’t be to pleased if I start again. :unamused:

The various models of “LSI-11” were made by the thousands, I suspect there are plenty of working examples out there.

In the 1980’s I was a partner in a consulting firm and we had a PDP-11/73 as our primary workhorse computer. I left the firm in 1990, but on visiting again in the circa 2005 they not only still had the machine but still turned it on from time to time to do real work.

However the older SSL based machines I suspect are pretty rare to find in working condition.

I know of a number of VAXes at universities, some working, some in storage. But no working PDP’s in my neighborhood. Perhaps I live in the wrong neighborhood? :ugeek:

I also have a customer who still uses a Philips P7000. Indestructible. It gets used with a number of terminals for text entry. The ladies who type in these books, or number lists, or whatever, score better than one error in 10.000 characters. No scanner with OCR beats them. And they do this while chatting…

Less critical data entry jobs go to Singapore. These people type in Dutch, French or German books without speaking the language. They’re slower and cheaper, but make more errors.

Of course, this company has their own spare parts, from second hand machines they’ve bought over the years. Philips stopped supporting these machines over 20 years ago. But they hardly ever get to use them.